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MARCH, 1921

MEMOIR 39

CORNELL UNIVERSITY
AGRICULTURAL EXPERIMENT STATION

THE GENETIC RELATIONS OF PLANT COLORS

IN MAIZE

R. A. EMERSON

ITHACA, NEW YORK
PUBLISHED BY THE UNIVERSITY

MARCH, 1921 MEMOIR 39

CORNELL UNIVERSITY
AGRICULTURAL EXPERIMENT STATION

THE GENETIC RELATIONS OF PLANT COLORS

IN MAIZE

R. A. EMERSON

ITHACA, NEW YORK
PUBLISHED BY THE UNIVERSITY

CONTENTS

PAGE

Previous investigations 8

Source and description of materials used 9

Purple, type 1 9

Sun red, type II 1 1

Dilute purple, type III ll

Dilute sun red, type IV 12

Brown, type V 14

Green, type VI 14

Relation of plant colors to environment 15

Sunlight a factor in color development 16

Moisture in relation to color 18

Temperature in relation to color 19

Soil fertility and color development 21

Rich compared with poor soil 21

Lack of particular nutrient elements 23

Relation of carbohydrates to color 26

Summary 28

Genetic analysis of color types 29

Crosses invohong the factor pairs A a, Bb, PI pi 29

Purple la x green VIc 29

Dilute sun red I\'a x brown V 32

Backcrosses of la x \'Ic and YVa, x V with IVa 34

Behavior of F2 color types in later generations 35

Intercrosses of F2 color types 48

Evidence from aleurone-color and linkage relations 58

Summary of results invohdng A a, Bb, PI pi 64

Crosses involving the multiple allelomorphs B, B"', b^,b 65

Interrelations of sun red I la, weak sun red lib, and dilute sun red IVa 67

Relation of weak purple lb to purple la, dilute purple Illa, and weak sun red lib 69

Crosses involving the multiple allelomorphs R'^, R^, R''3^ r*", r", r-*^'* 73

Green IVg x brown V 74

Intercrosses of F2 color types 86

Purple la x green -ant her ed dilute sun red Ill

Summary of results involving the allelomorphic series R^, Ro, R^, r'', ro, r^^ 112

Relation of aleurone factors C c and Prpr to plant color 113

Ex-pression of plant-color and aleurone-color factors 114

Summary 118

Literature cited 120

Appendix (containing tables) 121

THE GENETIC RELATIONS OF PLANT COLORS IN MAIZE

THE GENETIC RELATIONS OF PLANT COLORS IN MAIZE^

R. A. Emerson

Under the designation " plant colors " are included the colors other than
those related to chlorophyll, commonly seen in, but not limited to, such
external plant parts of maize as the culm, the staminate inflorescence,
the husks, the leaf sheaths, and to some extent the leaf blades. In con-
trast to this group are colors and color patterns related to chlorophyll or
associated with the pericarp and the cob, the silks, the endosperm, the
alem'one. The colors included in the group considered here are due to
water-soluble pigments, but the same is true of some of the other color
groups named above. Moreover, colors of the chlorophyll group (Lind-
strom, 1918) are found in the same plant parts as are the " plant " colors
considered in this account. The plant colors as a whole are closely
interrelated, but they are closely related also to aleurone colors and to
certain of the silk and pericarp colors. It is obvious, therefore, that,
while this classification is a more or less natural one, it is based primarily
on convenience.

The term " genetic relations " in the title to this memoir is to include
not merely an account of the genetic analysis of the material at hand by
means of hybridization experiments — tho that constitutes the greater
part of the paper — but also some consideration of the variations of the
several color types induced by or associated with environmental diver-
sities. Some httle attention to matters of this kind was made necessary
by the fact that presmnably homozygous material exhibited marked
variations in extent and intensity of pigmentation when grown under diverse
conditions. Since, as will be apparent later, the principal differences
between certain of the color types under investigation are apparently
quantitative ones, and since the materials at best exhibit no little complex-
ity with respect to factorial interrelations of a genetic nature, little progress
could have been made without some notion of the response of particular
color types to certain factors of the environment. But this study has

' Paper No. 78, Department of Plant Breeding, Cornell University, Ithaca, New York.

7

8 R. A. Emerson

been wholly subsidiary to the main purpose, namely, a genotypic analysis
of the color types under observation. The writer's realization of the
superficial nature of the environmental studies reported in this account
in no way weakens his belief in the importance of acquiring an accurate
knowledge of the chemistry of the pigments concerned and of instituting
fundamental investigations into the physiology of their development —
problems that must await the interest and effort of other workers.

The studies reported here were begun in a small way in 1909 and have
been continued, along with other problems in the genetics of maize, to
the present time. The work was conducted at the University of Nebraska
and supported by funds of that institution from 1909 to 1914. During
1911 facilities for growing and studying a considerable part of the cultures
then in hand were generously afforded the writer by the Bussey Institu-
tion at Harvard University. Since 1914 the work has been conducted
at Cornell University.

During these years, the v/riter has been assisted by a number of persons,
among whom he desires to mention particularly Dr. E. W. Lindstrom and
Dr. E. G. Anderson. Some data from the records of students associated
with the writer are included in this account. The cultures giving these
borrowed data are indicated in the tables by initial letters preceding the
pedigree numbers, as follows: A = E. G. Anderson, L = E. W. Lind-
strom, and S = Sterling H. Emerson.

The illustrations are from water-color drawings by C. W. Redwood,
Miss Carrie M. Preston, and Miss Bernice M. Branson.

PREVIOUS INVESTIGATIONS

So far as the writer is aware, little work with the plant colors of maize
has been reported previous to this time. Webber (1906) reported the
results of studies of the interrelations of aleurone, silk, anther, and
glume colors, with the conclusion that color in all these parts is closely
correlated but that there are definite breaks in the correlation. This
conclusion, in terms of present-day usage, is apparently equivalent to
the idea of close linkage with some crossing-over. East and Hayes (1911)
identified certain aleurone-color genes, which are shown in the present
account to be related to plant colors as well as to aleurone colors, and
reported data concerning the inheritance of silk and anther colors. The
writer (Emerson, 1918) added another aleurone-color pair also known to

Plant Colors in Maize 9

be concerned in plant-color development. He had earlier (191 1) announced
some of the plant colois discussed in the present paper and placed on
record some evidence as to their genetic behavior. Gcrnert (1912)
described types of maize that differ widely in color of anthers, glumes,
silks, sheaths, and husks, and reported simple mendelian behavior in Fi
and Fo of certain crosses. With this exception, Gernert's extensive investi-
gation of plant-color types has not been reported, but the writer has been
able, thru an exchange of material, to compare some of Gernert's types
with those in his own cultures.

SOURCE AND DESCRIPTION OF MATERIALS USED

The plant-color types discussed in this paper came in the main from
the crossing of two little-known varieties, one of which was obtained at a
national corn exposition and the other from an exhibit at a local agri-
cultural fair. One of the color types produced by this cross is the same as
that of the dent varieties generally grown thi-uout the Corn Belt; a second
is not infrequently seen in certain pop, flint, and sweet corn varieties;
and a third occurs in the fields of flour corn of certain Indian tribes of
the Southwest. One of the color types produced by the cross had no
existence, so far as the writer knows, until it appeared in his cultures.
Modifications of several of the six color types noted above have been
produced by crossing with a color type common in a few varieties of
sweet corn and closely related to the type most common in field maize.
The principal color types concerned in this account are discussed in some
detail in the descriptive notes below. They are:

I — Purple
II — Sun red

III — Dilute purple

IV — Dilute sun red
V — Brown

VI — Green

PURPLE, TYPE I

Material of the purple type was first obtained as a single ear from a
local agricultural fair at Nehawka, Nebraska, in 190G. The varietal
name is unknown. The uncrossed stock was a smooth-seeded pop corn

10 R. A. Emerson

of medium size. No other stock of purple has been used in the crosses
described later in this account, and the writer has never seen this color
type in cultivation outside his own cultures. A sample of dent corn of
apparently the same color tj^e was seen at a national corn exposition
in 1909. A stock of purple was obtained from Dr. Gernert in 1914 but
was not used in genetic studies. Another stock of purple was received
more recently (1919) from Messrs. Collins and Kempton, the seed having
come originally from Bolivia.

Seedlings of the purple type are usually indistinguishable from those of
types II, III, and IV (described more fully under type IVa, page 12),altho,
unUke the other types, they develop some color when grown in darkness.
Half-grown plants of type I usually have the lower sheaths prominently
colored, in which respect they exceed type II plants in intensity of pig-
mentation and are sharply differentiated from types III and IV. At the
flowering stage, plants of type la have much purple color in nearly all
parts, such as the cuhn, the brace roots, the leaf sheaths, the husks — even
the inner ones — the cob, and the staminate inflorescence including the
rachis, the spikelets, and the anthers (Plates I, 1, and V, 1). In some
cases the color extends over the whole leaf, and it is always seen in
the midrib. The purple pigment of type la develops in local darkness,
as has been shown by covering various parts of growing plants with several
thicknesses of heavy black paper (Plate VIII, 1). The color persists in
mature plants with slight fading in the outer parts due to weathering (Plate
VII, 1). The pericarp of type la is either colorless, red, or cherry, and
the aleurone is either purple, red, or colorless. With red aleurone the
anthers are reddish purple, and with cherry pericarp they are usually
very dark purple, almost black (Plate I. 2 and 3).

A subtype of purple known as weak purple, or type lb, is similar to la
but the pigmentation is less intense, particularly in the cuhn and the
inner husks (Plate V, 2). In early stages of growth it is often difficult
to distinguish lb from Ha. The anthers of lb are usually deep purple,
as are those of la, and the pericarp is the same as for la. Another sub-
class of purple, Ig, is like la except that the anthers are green (Plate I,
4) and the pericarp is red or colorless, never cherry. The aleurone color
is the same as in la.

Plant Colors in Maize 11

sun red, type ii

Sun red, the not a common color type, is encountered in a few varieties
of sweet corn and pop corn. It is always produced in F2 of certain crosses,
notably in purple x green.

While this type is less highly colored than la, it has such strong color
that it is not easily distinguished from the latter in early stages of growth.
At the flowering stage, type Ila is sharply differentiated from type la in
several respects. The staminate inflorescence of Ila is lighter than that
of la, and the anthers are deep pink instead of purple (Plate III, 1). In
type Ila, pigmentation of the cuhn, the leaf sheaths, and the husks is
limited almost wholly to parts exposed to sunlight, hence the name sun
red. The inner husks are therefore without red color, and rarely does
much color develop in any but the outer layer of husks (Plate V, 3) not-
withstanding the fact that sufficient light penetrates to the inner husks to
induce the development of some chlorophyll in them. A tassel inclosed
in a black paper bag produces no red color in either glumes or anthers
(Plate VIII, 4). Since the color of sun red plants is so largely superficial,
it disappears almost wholly from mature plants thru weathering (Plate
VII, 2). Sun red plants have either red or colorless, but never cherry,
pericarp, and either purple, red, or colorless aleurone.

Sun red of type Ilg differs from Ila merely in having green instead of
pink anthers. Type lib, known as weak sun red, differs from Ila in the
lesser intensity and extent of its pigmentation. Particularly the leaf
sheaths and the husks are less highl}^ colored than in type Ila. Often
the color of the husks develops in alternate dark and light bars parallel
to the upper margins of the overlapping husks (Plate V, 4). Types lib
and llg have the same pericarp and aleurone colors as Ila.

DILUTE PURPLE, TYPE III

The dilute purple type, as well as the sun red, occurs regularly in F2
of purple X green, and most of the dilute purple material in the writer's
cultures came originally from this and other cro.sses. It was first
observ'ed in the progeny of such crosses in 1909. Recently two stocks of
this color type have been received from G. N. Collins, one obtained from
the Hopi Indians of southwestern United States and the other from
Bolivia.

12 R. A. Emerson

Seedlings and young plants of type Ilia show no more color than do
those of type IVa, and apparently do not develop color in darkness. As
the plants approach the flowering stage, they usually show somewhat
more color than do plants of type IVa, particularly at the base of the culm
and in the brace roots, and sometimes in the leaf sheaths. The staminate
inflorescence is usually, tho not always, somewhat more highly colored
than that of type IVa. The anthers are deep purple, like those of type
la (Plate II, 1). With red aleurone the anthers are usually reddish purple,
and with cherry pericarp they are dark purple, sometimes appearing
nearly black (Plate II, 2 and 3). The anther color develops fully in dark-
ness, but the glumes are slightly if at all colored when protected from light
by black paper bags (Plate VIII, 3). As the plants mature, considerable
color develops in the inner husks (Plate VII, 3), on the leaf sheaths, and
particularly in the culm even where it is protected from strong Ught by
the sheaths. In some cases the culm and the sheaths ultimately become
nearly as strongly pigmented as type la, but ordinarily the mature plant
is considerably less highly colored than the purple type (Plate VII, 4).
The color seen in mature plants develops well in local darkness, in which
respect also type Ilia is hke la. Dilute purple differs from purple, there-
fore, mainly in a less intense pigmentation and in a delayed development
of pigment. The pericarp of type Ilia is either red, cherry, or colorless,
and the aleurone is either purple, red, or colorless, just as in type la.

There exists a type of plant color which is closely related genetically
to type Ilia, but which lacks red or purple color in culm, sheaths, silks,
glumes, and anthers and is consequently known as Green, type Illg
(Plate II, 4). The aleurone of this type is either purple, red, or colorless,
and the pericarp is either red or colorless, never cherry. With respect
to aleurone and pericarp, therefore, type Illg is like type Ig.

DILUTE SUN RED, TYPE IV

Dilute sun red is the commonest color type of maize in cultivation. It is
practically the only color type seen in the dent varieties grown in the Corn
Belt of the United States, and is common in flint, flour, sweet, and pop
corns. Like the sun red and the dilute purple types, it always appears
in crosses of purple la with green Vic.

The seedlings of type IVa usually show more or less sun red pigment
in the coleoptile, the leaf sheath, and the leaf margins. The young

Plant Colors in Maize 13

plants ordinarily have considerable color at the base of the lower sheaths,
but little or no color except green in other parts except in the margins of
the leaves (Plate IX. 1). When the plants are grown on infertile soil,
much bright red color develops in all parts exposed to light except the
youngest leaves (Plate IX, 2). The seedlings and the very young plants
are not ordinarily distinguishable from those of types la, Ila, and Ilia.
Some time before the flowering stage, the plants of this type are sharply
differentiated from those of types la and Ila, and are usually somewhat
less highly colored than those of type Ilia. In normally grown plants,
the color is confined mostly to the brace roots, and to the sheaths and the
exposed parts of the culm at the base of the plants. Even at the flowering
stage almost no color is seen in the upper sheaths or the upper part of the
culm, and very Uttle in the husks (Plate VI, 1). The staminate inflores-
cense is colored much as is that of the sun red type, tho the glumes are
lighter than those of type Ila and the rachis is usually nearly devoid of
color. The anthers show more or less pink, as do those of type Ila.
There is much variation in the extent and intensity of pigmentation of
glumes and anthers (Plate III, 2, 3, and 4), due in part to genetic differ-
ences and in part probably to environmental influences. Late in the
life of the plant, type IVa usually shows some color in the outer husks and
also in exposed parts of the culm. Different strains show considerable
variation in this respect (Plate VI, 1 and 2). Due to the slight develop-
ment of pigment and because of weathering, the dry parts of mature
plants show little red color (Plate VII, 6). Light is essential to the
development of color in dilute sun red, IVa, just as in sun red, Ila. The
aleurone and pericarp colors of dilute sun red, IVa, are the same as those
of sun red, ITa.

A wholly green type, that is, one devoid of pigment other than green
in the plant parts here under consideration, is closely related genetically
to type IVa and is therefore known as type IVg (Plate II, 4). Phenotypi-
cally it is the same as type Illg. Just as in case of types Ig, II, Illg, and
IVa, the pericarp of IVg is either red or colorless, never cherry, and the
aleurone is either purple, red, or colorless. Genotypic diversities in the
amount of color are noted for type IVa above. The lightest types of
dilute sun red show no color except mere traces of red in the staminate
spikelets. This condition is found in most plants of at least two varieties
of sweet corn, Black Mexican and Crosby. From these varieties there

14 R. A. Emerson

have been isolated strains that lack even this minimum of color. These
strains furnished the original stock of type IVg. In no environment as
yet encountered has any red or purple plant color developed in type IVg.

BROWN. TYPE V

The brown type was first seen in 1912, when it occurred in F2 of the cross
purple la x green Vic. So far as the writer has been able to learn, brown
plant color had not been reported previously, and he is unaware of its
existence outside of his own cultures or of stocks grown from them.

Seedlings and young plants of type V are wholly green. Before the
flowering period is reached, a brown pigment begins to appear in the
lower sheaths. At the time of flowering^ the culm, the sheaths, the
husks (Plate VI, 3), and the staminate inflorescence (Plate IV, 1 and 2)
are brown. The anthers are usually green. The brown color extends
to the inner husks, to the culm beneath the leaf sheaths, and to the cob
(Plate VII, 5). That light is not essential to the development of brown
is shown further by the fact that the color appears under several thick-
nesses* of black paper (Plate VIII, 2). It is not uncommon to find traces
of purple associated with the brown in the brace roots and at the base of
the inner husks (Plate VI, 3). Abnormally developed tassels, not infre-
quently seen on plants grown in small pots in the greenhouse, in some
cases show a little purple (Plate XI). The aleurone of brown plants is
always colorless, except for xenia grains, and the pericarp is either brown,
brownish, or colorless, never red nor cherry. Brown pericarp color of
type V corresponds to red of types I, II, III, and IV, and brownish to
cherry of types I and III.

GREEN, TYPE VI

The writer's stock of the green type originated from a single ear obtained
at a national corn exposition held at Omaha in 1909. The corn was
exhibited from southern Missouri, where it is grown locally. It is a
large dent variety, rather late in season.

Cultures of type Vic, derived from this stock, show no plant color other
than green at any stage of development or under any environmental
conditions to which they have as yet been subjected (Plates IV, 3, and
VI, 4).

Plant Colors in Maize 15

• Three subclasses of type VI are recognized. One of these, Via, is Hke
Vic in every respect except that a shght amount of brown is sometimes
seen in the outer husks and sheaths (Plate VI, 5). The second, VIb. is
green except for a slight tinge of brown in the spikelets of the staminate
inflorescence (Plate IV, 4). As a rule, the development of brown pigment
in Via and VIb is not sufficient to differentiate with certainty the one
from the other, or either from Vic. The three subclasses, a, b, and c,
are therefore usually classed together as type VI. Both Via and VIb
have been isolated from crosses involving Vic. The aleurone of all type
VI plants, just as in those of type V, is colorless, except for such color as
may be due to xenia. The pericarp of Via and Vic is either brown or
colorless, never brownish, while that of VIb is brown, brownish, or color-
less, as in the case of type V. With brownish pericarp,, type VIb usually
shows unmistakable brown color in the staminate spikelets.

RELATION OF PLANT COLORS TO ENVIRONMENT

From the preceding descriptive notes and accompanying illustrations,
it is clear that many of the differences separating the six major color types
and their several subclasses are quantitative. Purple plants are more
strongly colored than are sun red or dilute purple plants. Dilute sun
red plants have less color than sun red or purple plants. Weak purple
plants have less color than purple ones, but more than dilute purple ones,
and weak sun reds are intermediate between sun reds and dilute sun reds.
Dilute sun red plants vary, from those showing considerable color to those
which, except for green, are nearly colorless. Wholly green plants are
classed as subgioups of both dilute purple and dilute sun red. The
subclasses of type VI differ so little with respect to color that they are
ordinarily thrown together as one green type. Heterozygous brown
plants are lighter than homozygous ones, and, since more than one factor
pair is concerned; there is a fairly smooth gradation from the darkest to
the lightest browns. Plants of types Via and VIb, when they show any
brown, differ in the parts colored. The color of the staminate inflores-
cence, and even of other parts, of purples, dilute purples, browns, and
greens of type VIb is darker when the pericarp is cherry or brownish than
when it is red, brown, or colorless.

The natural intergrading of genetic types in this somewhat complex
series is often made still more confusing by the variations accompanying

16 R. A. Emerson

environmental diversities. A prominent geneticist, on observing some
of the writer's cultures, was led to say that there were no sharply differ-
entiating characteristics by which other than an arbitrary classification
could be made, and asserted that he could select from a single progeny a
series grading from the darkest to the lightest colors. The writer has
some doubt that this could have been done, but the instance illustrates
well the difficulties that confront one unacquainted with the materials.
It is fortunate that some enviromnental influences which increase the
difficulty of assorting certain color types make other types stand out more
sharply than they otherwise would. Without some notion of these envi-
ronmental effects, a genetic analysis of the material would indeed be
difficult.

SUNLIGHT A FACTOR IN COLOR DEVELOPMENT

The relation of sunlight to the development of color has been noted
briefly in the descriptions of some of the color types. The effects of
sunlight or of local darkness, instead of adding to the confusion of color
types, afford a means of sharp differentiation between certain types.
So far as is known at present, no color develops in sun red or dilute sun
red plants, or in the early stages of growth of dilute purple plants, except
under the influence of fairly strong light. In the case of purple and of
the later stages of growth of dilute pm-ple, there is no doubt that the
color develops more rapidly at first in light than in darkness, but ulti-
mately color develops fully, or apparently so, even in local darkness
(Plate VIII). The seedlings of purple plants develop some color when
germinated and grown in a dark chamber where no part of the plant receives
light. There is some, tho very little, evidence that the development of
brown pigment of type V is hastened by the influence of light, and what
little brown color ever develops in type Via is confined to parts exposed
to sunlight (Plate VI,, 5).

It would not be surprising to find that the pigments seen in the purple,
dilute purple, sun red, and dilute sun red types are the same chemically.
In fact they look alike in water solution and apparently react in the same
way to simple chemical tests. If they prove to be identical, it would seem
to follow that purple and dilute purple plants have some inherent
mechanism, perhaps an organic catalyzer, capable of initiating or hasten-
ing chemical reactions, and that this mechanism is lacking in sun red

Plant Colors in Maize 17

and diluto sun rod plants, in which the same reactions may possibly be
brought about thru the action of sunlight.

Usually a single thickness of black paper, such as is employed to pro-
tect photographic plates from light, is sufficient to prevent the develop-
ment of color in sun red plants (Plate VIII, 4). That more intense light
is necessary for the production of sun red pigment than for the production
of chlorophyll is shown by the ahnost entire absence of red color in all
but the outer husks, while even the innermost husks are somewhat green
(Plate V, 3). The pigments of purple and brown plants, on the contrary,
develop well even when there is too little light for the formation of chloro-
phyll (Plate VIII, 1 and 2).

That the effect of light on color development is a definitely local one is
shown by the sharp fine of demarcation between colored and colorless
areas in culms, husks, and sheaths partly exposed and partly protected
by overlapping sheaths or husks (Plate V, 3). Even a single piece of
wrapping cord tied closely about a young ear, sheath, or culm of a sun
red plant is sufficient to prevent the development of color beneath it.
Evidently sun red pigment does not diffuse appreciably from the cells in
which it forms. It is not meant to suggest by these observations that
sunlight has no effect other than a local one on color development. On
the contrary, there is evidence that the development of sun red color is
influenced bj^ the presence of an abundance of carbohydrates which in
turn are dependent on sunlight for their foraiation.

A striking example of the relation of sunlight to color development is
afforded by the barred pattern seen in the husks of some weak sun red
plants (Plate V, 4). The pattern consists of alternate bars of red and green
parallel to the upper margin of the overlapping husk next below them. By
tracing in pencil on each exposed husk of a rapidly growing ear the margin
of the husk overlapping it, it has been ascertained with certainty that the
red bars correspond to the areas that are pushed out from under the over-
lapping husk between early morning and late afternoon; while the green
bars correspond to the areas pushed ,out during the late afternoon and
night. Why color develops in only those parts of the husk that receive
the sunlight when first exposed to the air, and not in the parts exposed
some hours previously, is not known. Another illustration of the effect of
sunlight on freshly exposed husks was seen in a very light type of weak
sun red (Plate V, 5). Of two ears on the same cuhn, both very lightly

18 R. A. Emerson

and about equally colored, the lower had its husks torn apart in the early
forenoon so that the fresh inner husks were exposed at once to direct sun-
Ught. In a few hours some red color began to show, and in a few days all
the newly exposed husks were brilliantly colored, while the undisturbed
upper ear remained only slightly colored. Similar results followed in
repeated trials, and, in fact, failed only when the atmospheric conditions
were such as to cause the newly exposed husks to wither during the first
day. It is of interest to note also that similarly treated ears of dilute
sun red plants, which rarely show any red color in the outer husks of j^oung
ears, failed to develop color when the husks were torn apart, even tho
they remained fresh for some daj^s.

It is evident from all this, that, with respect to their relation to sunlight,
there exists a series of color t^q^es varjdng more or less abruptly from
dilute sun red, in which little or no sun red develops in even freshly exposed
husks, thru weak sun red, in which color fomis in only freshly exposed
husks, and strong sun red, in which much color develops in all exposed
parts of the husks but not in parts protected from light, to strong purple,
in which, tho sunlight may hasten color development, it is not essential
to its foraiation.

Tests of the influence on color development of light of different wave
lengths have not been uniformly successful. Cramer photographic color
screens were placed in partial contact with the uncolored inner husks of
sun red plants, and the entrance of light otherwise than thru the screens
was prevented by means of strips of black paper. These screens, by
cutting out light of certain wave lengths, not only change the quality of
Ught passing thru them but lessen the intensitj'' of the light. While the
results, therefore, can have Uttle value, it may be of interest to physiolo-
gists to note that considerable sun red formed under the orange and the
bright red screens, and little or none under the green and the blue screens.

MOISTURE IX RELATION TO COLOR

It is well known that under field conditions maize does not grow well in
wet soil. In such situations, not onl}'^ are the plants small, with their
leaves pale green, but they often develop much red pigment. The writer
has repeatedly observed that young plants, in flooded parts of fields where
the soil had been covered with water for some days, were brilliantly red
in all parts except the youngest leaves, while near-by plants on slightly

Plant Colors ix Maize 19

higher land showed only the slight red at the base of the culms character-
istic of young dilute sun red plants.

For a study of the effect of soil moisture on color development under
controlled conditions, plants of well-known stocks of purple la, sun red
Ila, dilute purple Ilia, dilute sun red IVa, brown V, and green Vic and
IVg, were grown in rich soil in earthen jars in the greenhouse during
the summer of 1914. When the plants had reached a height of from
10 to 15 centimeters, the jars were separated into three lots — one with
dry soil, another with moist soil, and a third with wet soil. The dry-soil
lot received only sufficient water to keep the plants growing slowly and not
enough to prevent wilting during the hotter part of the day. The moist-
soil lot received just sufficient water to insure normal growth. The wet-
soil lot was kept constantly in saturated soil with some free water above the
soil surface. The test was continued until the plants of all lots reached
the flowering stage.

The plants in moist soil made the most rapid growth and flowered some-
what earlier than the plants of the other lots. Their leaves were of normal
green color and they showed the colors characteristic of the several color
types. The plants in dry soil were smaller and very dark green. The
development of purple, red, and l^rown color was practically the same as
with the plants in moist soil. The plants in wet soil grew less rapidly than
those in moist soil, but more rapidly than those in dry soil. Their leaves
were somewhat lighter green than those of the moist-soil lot, but they
showed practically the same amount of purple, red, and brown color. In
fact the only differences between the three lots with respect to color at
any time during the test were such as might well be related to the stage of
development of the plants. All color types show more color in the later
stages of growth. The moist-soil lot developed somewhat more rapidly
than did the others and for a time showed slightly more color, but ulti-
mately all lots had practically the same amount of color. Evidently the
reddening of plants iri flooded fields is not due directly to the excess of
soil moisture.

TEMPERATURE IN RELATION TO COLOR

Since moisture is not the direct cause of the reddening of maize plants
in flooded fields, tho certainly connected with the phenomenon in some
way, it follows that the effect must be produced by some indirect action

20 R. A. Emerson

of the excess of water. Wet soils in spring are cold soils, and if the wet
areas are of considerable extent the air above them is doubtless somewhat
cooler than that above drier soil. It has been frequently observed
that young plants which show much color during a cold spring
show considerably less in the leaves developed after the weather has become
wanner. Young plants of early-planted maize sometimes have more
color than plants that are started later. Moreover, full-grown plants
from late plantings often develop more color in the cool weather of autumn
than similar plants that mature in the warm weather of late smiimer.
It seemed important, therefore, to study the effects of various tempera-
tures on color development.

The same color types and the same stocks — in one test the identical
plants — used in the soil-moisture test were grown in the greenhouse under
diverse temperatures. Altho both rich and poor soils of diverse water
content were used, the comparisons noted here were made between plants
in the same kind of soil and with practically the same soil-moisture con-
ditions. Two lots were grown during the winter of 1913-14 and two dur-
ing the following summer. During the winter, one lot was kept in a warm
house at temperatures varying from about 18° to 26° C, and one was
kept in a cool house at temperatures varying normally from about 7° to
15° C. but during a part of the test dropping at night to l°or 2° C. Both
lots were exposed to the full winter sunlight of the houses. During the
sunmier test, one lot was kept as cool as possible by partial shading and
free ventilation, the temperatures ranging from about 15° to 40° G. but
occasionally exceeding these limits, and the other lot was kept in an
unshaded house the ventilators of which were never opened. The night
temperatures of the closed house averaged not more than one degree
higher than those of the open house, but the maximum day tempera-
tures in the closed house varied usually from about 44° to 50° G. and on
three consecutive days reached 55° G. This extreme heat killed most
of the plants grown in rich soil but did not seriously injure those in poor
soil. Of course the relative humidity, as well as the intensity of the
light, was materially different for the closed and the open house.

As a result of these tests, no final differences in the development of
color in any of the color types were observed between the lots grown
at the very diverse temperatures. Of course differences were observed
at certain times, but they are readily accounted for by the facts that the

Plant Colors ix IMaize 21

plants developed less rapidly at both excessively high and excessively
low temperatures than at more moderate temperatures, and that color
shows less during the early stages of development than during later stages.
It may be safely concluded, therefore, that color development in maize
is not notably influenced, except perhaps indirectly, by diverse temper-
atures.

SOIL FERTILITY AND COLOR DEVELOPMENT

There is still another way in which it was thought the excess of water
might indirectly affect the development of color in maize plants in flooded
fields. Not only may nutrient salts be removed in part by an excess of
water, but certain of these salts — nitrates — are not fomied normail}^
in very wet soils. Tests were made, therefore, of the relation of soil
fertihty to color development.

Rich compared with poor soil

The same plant-color types as were employed in the soil-moisture and
temperature tests were included in these soil-fertility tests. In fact, for one
of the tests the same plants were used as in the moisture and temperature
studies. One lot of plants was grown in rich soil and a duplicate lot in
poor soil. Field soil furnished the basis of both soils. To one lot was
added about 50 per cent by measure of thoroly decayed stable manure,
and to the other about 50 per cent of clean sand.

The effect of soil fertility on color development of certain color types
was strikingly apparent from the time the seedlings were two or three
weeks old. At this age and for some time later, there was no appreciable
difference in color between purples, sun reds, dilute purples, and dilute
sun reds. In the rich soil all these color tjqjes had very little red color.
There was some color in the coleoptile and the lower leaf sheath, but none
in the leaf blades except for a slight amount in their margins. The same
color types in poor soil had considerable color in the leaf blades and much
color in the leaf sheaths. The plants in rich soil grew rapidly and were
dark green, even the lower leaves remaining healthy. The plants in i)oor
soil, on the contrary, grew less rapidly and were lighter green, and their
lower leaves soon became yellow and died. In all cases the leaf blades
became brilliantly red before they died. This is in strong contrast with
the condition of the lower leaves of plants m diy, rich soil. When the

22 R- A. Emerson

death of the lower leaves is caused by drouth, there is no corresponding
development of red color.

At the age of six weeks, the plants in rich soil were beginning to show
slightly the color differences that in later stages are characteristic of
purples, sun reds, dilute purples, and dilute sun reds. In poor soil, on
the contrary, no color differences were seen. All the four types were
highly colored thruout except for the youngest leaves (Plate IX, 1 and 2).

At the flowering period, the plants in rich soil exhibited all the
peculiarities of color by which purples, sun reds, dilute purples, and dilute
sun reds are normally differentiated. Even in the poor soil something
of the same color differences were discernible between the purples and
sun reds on the one hand and the dilute purples and dilute sun reds on
the other, but it is doubtful whether these two groups could have been
separated accurately from a mixed culture. It would have been very
difficult also to separate with certainty the purples from the sun reds
or the dilute purples from the dilute sun reds, except by differences in
anther color and by an examination of the inner husks and other parts
protected from sunlight. Differences between the plants in rich and in
poor soil were still pronounced in the case of dilute purples and dilute
sun reds, but were scarcely discernible in the case of purples and sun reds
except that the leaf blades were somewhat more highly colored with poor
than with rich soil and that thruout the plants the colors appeared
brighter in the former case owing to the less intense green of the poor-
soil lots.

The seedUngs of both brown and green color types showed no brown
nor red color in either the rich or the poor soil. At the age of two months,
some brown pigment began to show in the lower sheaths of the brown
type, and at the flowering stage the plants had the typical coloration of
brown plants. The difference in the development of brown between rich
and poor soil was at no tune very noticeable. The color showed perhaps
slightly earlier, and was perhaps slightly more intense, with the poor
soil. Even this apparent difference, however, may have been due merely
to the fact that the plants in poor soil were fighter and more yellowish
green than those in rich soil. Dark green might readily mask the brown
color somewhat. Green plants of both type Vic and type IVg exhibited
no red nor brown color at any stage of development in either rich soil
or poor soil.

Plant Colors in Maize 23

From these observations it is apparent that variations in soil fertihty
may effectively obscure genetic differences. A knowledge of the influence
of soil fertility on color development is therefore essential to careful genetic
work with the plant colors of maize. IMoreover, since soil fertility is
subject to control thru cultural methods, different degrees of fertility
can. be used as an aid to the sharp differentiation of certain genetic types.
If, for instance, it is desired to separate, in the seedling stage, greens
and browns on the one hand from the red-purple series on the other,
this can he accomplished most readily in poor soil. In fact, the writer's
practice, in studies requiring this separation, is to grow the seedlings in
pure sand. In this medium seedlings of the purple-red series of color types
become highly colored at a very early age, while seedUngs of the green
and brown types show absolutely no red color. If, however, it is desired
to distinguish sharply between purple and dilute puiple or between sun
red and dilute sun red, fairly fertile soil is essential, and, usually, the
more fertile it is, the more easily can the separation be made. The stronger
colors develop almost as well in rich as in poor soil, while the weaker
colors develop much less intensely in rich soils than in poor ones. On
very poor soils, it is difficult to separate sun reds from dilute sun reds,
and almost if not quite impossible to distinguish with certainty between
sun reds and weak sun reds or between weak sun reds and dilute sun reds.

Lack of particular ivdrient elements

It having been established that differences in soil fertility result in marked
differences in the development of red color in maize plants, it seemed
important to determine whether particular nutrient salts are more con-
cerned than others. Accordingly, plants of all the color types included
in the tests previously reported were grown in glazed earthen jars in
clean quartz sand and watered with nutrient solutions. The quartz
sand was obtained from the Department of Agronomy of the University
of Nebraska, and was known to be practically free from nutrient elements
except iron. The nutrient salts and distilled water were obtained from
the Department of Agricultural Chemistry of the same institution. The
nutrient solution employed was one that had given good results with maize
in certain experiments conducted previously by the Department of
Agronomy. The complete nutrient solution, 0.2 j^er cent strength,
contained per liter of water the following salts: 1 gram Ca (N03)2, 0.25

24 R. A. Emerson

gram KNO3, 0.25 gram K2HPO4,. 0.25 gram MgS04, and 0.25 gram NaCl.
Other solutions of approximately equivalent molecular strength, but each
lacking one of the nutrient elements of the complete solution, were used.
In the nitrogen-free solution, 0.7 gram CaCl2 and 0.22 gram K2SO4 were
substituted for Ca(N03)2 and KNO3, respectively; in the phosphorus-free
solution, 0.25 gram K2SO4 for K2HPO4; in the potassium-free solution,
0.2 gram NaNOs and 0.2 gram Na2HP04 for KNO3 and K2HPO4,
respectively; in the calcium-free solution, 1 gram NaNOs for Ca(N03)2;
in the magnesium-free solution, 0.3 gram Na2S04 for MgS04; and in the
sulfur-free solution, 0.2 gram MgCl2 for MgS04. A complete nutrient
solution of four times the strength indicated above, 0.8 per cent, was
also used, and one lot was given water without the addition of nutrients.
After the first three weeks, the nutrient solutions were all used at double
strength, 0.4 and 1.6 per cent, and clear water was occasionally given.
This treatment, owing to considerable evaporation of water, doubtless
resulted in a gradual increase in the strength of the solutions. The tests
were carried on at the same time with one of the tests of rich and poor
soil, so that the latter might serve as a check on the nutrient-solution tests.

At first the seedlings given 0.2-per-cent complete nutrient solution
reacted about as did those in poor soil, while those given 0.8-per-cent
nutrient solution were no more highly colored than those in rich soil.
At one month of age, the plants watered for three weeks with 0.2-per-cent
and one week with 0.4-per-cent complete solution were growing rapidly
and were no more highly colored than those in rich soil, while the plants
in the very strong solutions (0.8 and 1.6 per cent) were begimiing to
wilt, perhaps from the toxic effect of the solutions. Thruout the remainder
of the test, the plants given 0.4-per cent solution, alternated occasionally
with clear water, were practically like those growing in rich soil both as
respects vigor of growth and color development.

In striking contrast to the plants given complete nutrient solution
were the ones given clear water and those in nitrogen-free nutrient solution.
Both these lots showed much color even at two weeks after germination,
and soon thereafter the seedlings were red to the tips of their leaves.
At the age of six weeks the plants of these two lots were much shorter
and slenderer than those given complete nutrient solution. Their upper
leaves were pale yellowish green, with much red, and the lower leaves
were dead but still showing the red color that had developed earlier.

Plant Colors in Maize 25

Next in point of coloration to the seedlings given nitrogen-froe nutrient
solution and those given water alone, were the ones grown in phosphorus-
free nutrient solution. The latter did not show red color so quickly as
did the nitrogen-free lot, and at no time did they develop quite so much
color. They showed, however, considerably more color at the age of one
month than did seedlings in the complete nutrient solution. When six
weeks old the plants of the phosphorus-free lot were relatively small,
and had pale green upper leaves with little red color and dead lower
leaves which still retained much red pigment. While somewhat larger
than the plants in nitrogen-free solution and those in clear water, the
phosphorus-free lot began wilting when about six weeks old and died
considerably in advance of the nitrogen-free lot. Their roots showed
early indications of injury, perhaps from toxic effects of the solution.

Plants of all the other lots, in which one or another nutrient element
had been omitted from the solution, exhibited little or no color reaction
to the lack of a particular element. All of them were more vigorous
in growth than the nitrogen-free and phosphorus-free lots, but much less
so than the lot given complete nutrient solution. The sulfur-free lot
for a time seemed to be developing more red, but later showed perhaps
even less red, than the lot with complete nutrient solution. The mag-
nesium-free lot showed prominent dark and light green stripes in the
leaves similar to the green-striped chlorophyll pattern (Lindstrom, 1918).
In some cases the tissue of the lighter stripes died and there was often
some red coloration next to the dead tissue. The potassium-free lot had
about the same amount of red color as the lot given complete nutrient
solution, while the calcium-free lot showed less red color than any other
lot in the test.

It is perhaps noteworthy that in the nitrogen-free lot, and to some
extent in the phosphorus-free lot. the new growth seemed to take place
at the expense of the older leaves. The lower leaves first became light
or yellowish green, then red, and finally died. That the development of
red pigment is not necessarily connected, however, with the breaking
down of the protoplasm, is seen in the failure of seedlings to develop
red color in the older dying leaves of the lot in complete nutrient solution
and of the potassium-free, magnesium-free, and calcium-free lots. In the
calcium-free lot, growth was stopped by the death of the youngest parts,
including the partly unrolled upper leaves, and yet these parts showed

26 R. A. Emerson

no red. Moreover, the dying of the lower leaves due to excessively dry
soil, or of the upper leaves from intense heat, is not accompanied by the
development of red pigment.

In similar tests with cuttings of Tradescantia viridis and T. lockensis
grown in distilled water, in complete nutrient solutions, and in solutions
each lacking one nutrient element, namely, N, P, K, Ca, Mg, or S,
Czartkowski (1914) found that after five weeks red color appeared in
the newly developed leaves in the cases of only distilled water and nitrogen-
free solutions. He states, however, that Susuki reported a similar effect
on plants of Hordeum from a lack of phosphorus. It will be recalled
that in the writer's tests with maize, lack of nitrogen gave the most pro-
nounced effect and lack of phosphorus induced considerable color develop-
ment, while lack of sulfur seemed for a time to have an effect but no
effect was apparent later.

Frorh the results of the tests reported above, it is apparent that the
reddening of young plants in flooded fields, as well as the intensification
of color in older plants grown on poorly drained heavy soils, is not due
to any direct effect of the excess of water in the soil or to a direct effect
of the somewhat lower temperatures accompanying such conditions, but
rather, perhaps, to the lessened fertility of cold, wet soils or to inability
of the plant to obtain adequate nutrients under such conditions. An
excess of water not only may remove certain nutrient salts from the soil,
but also may prevent or greatly check nitrification. Moreover, under
these conditions the soil solution is probably less concentrated. The
reddening of young plants in cold, wet soils in spring, the greater develop-
ment of color in plants maturing in the cool weather of late autumn, and
the excessive development of red in plants on very light sandy soils, are
possibly all due to the plants' inability to get from such soils an adequate
supply of nutrient salts, particularly of nitrates.

RELATION OF CARBOHYDRATES TO COLOR

Several authors, notably Wheldale (1911), have discussed the relation
of sugars to the production of anthocyanins in plants. Knudson (1916:
24, 62) found that maize and vetch grown in nutrient solutions containing
certain sugars developed markedly more red color than did plants grown
in sugar-free solutions. The writer has observed repeatedly an apparent
relation between an excess of carbohydrates and the development of red

Plant Colors in Maize 27

color in maize leaves. Of course the relation has been observed only in
typos that normally produce some rod pigment. Neither brown, type V,
nor green of either type IVg or type VI, has ever been observed with red
color in the leaves, no matter what treatment has been given the plants.
When loaves are folded at right angles to the midrib and the margin of
the fold is creased sufficiently to break the softer tissues but not enough
to break the water-conducting vessels, the part beyond the crease does
not wilt, but within a few days it begins to lose some of its chlorophyll
and within a week it becomes highly colored red (Plate X, 1). When leaves
are similarly treated late in the afternoon of a bright day and the plants
are kept in a dark room until the following day, the starch is, of course,
found to have disappeared by translocation from the part of the leaves
below the crease, while the cells of the bundle sheaths of the part beyond
the crease are found to be packed with starch. There is so much starch
in this part of a creased leaf that, on extraction of the chlorophyll with
alcohol and treatment with iodin, the whole end of the leaf becomes
almost black. While this does not prove a direct relation between an
excess of carbohydrates and the development of red pigment, taken in
connection with all the other observations it strongly suggests such a
relation.

It has been observed repeatedly that sweet-corn plants from which
the ears have been removed in the edible stage develop within a week
or two much more color than do neighboring plants that still retain their
ears. Barren stalks also frequently show more color than do their ear-
bearing neighbors. While no direct determination of the matter has been
made it seems likely that barren plants, as well as plants from which the
immature ears have been removed, may carry, in their leaves, husks,
and cuhns, an excess of carbohydrates which would normally have been
deposited in the developing seeds.

The strong development of red pigment in the white, chlorophyll-free
stripes of the japonica-striped type, when leaves are creased or when
plants are grown in poor soil, may well be due to the passage of sugars
from the green to the white parts. In some instances the red color seems
to develop more quickly in the white stripes than in the green (Plate X, 2).
Whether this difference is a real one, due perhaps to the readier access
of light to the white parts, or is only an apparent difference due to the

28 R. A. Emerson

masking effect of the green color, is not known. Certainly red pigments
develop first in the chlorophyll-free epidermal cells.^

Czartkowski (1914) suggested, in connection with the account of his
study of the relation of nutrient elements to color development, that
lack of nitrogen may check protein synthesis, thus leaving unused the
carbohydrates that would otherwise be used in growth, and that the
excess of carbohydrates may favor anthocyanin formation. He was
unable to understand why a lack of phosphorus or of sulfur did not like-
wise influence color development, since these elements also are necessary
to protein synthesis. Lack of phosphorus does apparently bear some
relation to color development in maize, but the v/riter's tests afforded
little or no evidence of such a relation between a lack of sulfur and pigment
formation. If lack of nitrogen induces anthocyanin formation thru the
checking of growth, thus allowing an accumulation of carbohydrates, it
is not clear why other means of checking growth, such, for instance, as
dry soil, do not also favor pigment formation, unless these other growth-
checking factors at the same time limit photosynthetic activity. It is
of interest to recall in this connection that plant colors of maize — brown
no less than the red-purple series — develop first in the older parts where
growth first ceases, such as the lower sheaths and the upper parts of the
internodes of the culm.

SUMMARY

Whatever is the final outcome of studies of the relation of environmental
factors to plant-color development in maize, enough has been noted to
indicate a very complex relation. What is more complex than this chain
of events — a chain that lacks many links in the way of particular chemical
reactions: cold, wet soil checks or inhibits nitrification; lack of nitrogen
in available fonn limits protein synthesis, which in turn allows an accumu-
lation of carbohydrates; an excess of carbohydrates favors anthocyanin
formation. The result is that young maize plants in cold, wet soil
become highly colored. But to all this must be added the factor of
sunlight, without which no red color develops in the leaves of young
plants. And not the least consideration is the important fact that only
plants of certain genetic constitutions show this color reaction to wet
soils. It is to be hoped that some day, thru the coordinated efforts of

2 The histology of color development of the several plant-color tvpes has been investigated by Dr. E. G.
Anderson, but the observations have not been published.^"

Plant Colors in Maize 29

biochemists, physiologists, and geneticists, it may be possible to reach
conclusions in this field of quite as fundamental importance to biology
as the recent results of similar efforts of cytologists and geneticists.

GENETIC ANALYSIS OF COLOR TYPES

In the preceding parts of this paper the several plant-color types of
maize are described and the variations induced in them l)y diversities
of environment are discussed. The remainder of the paper is devoted to
a presentation of data of a more distinctly genetic nature, and to an
attempt at a factorial analysis of these data.

The data are presented as if the F2 generation of the more complex
crosses were the first which were obtained and on which hypotheses were
formulated and appropriate tests made. As a matter of fact, this was
not in all cases the actual procedure. In several instances the results of
some of the simpler crosses were at hand and were used as an aid to the
interpretation of the more complex ones when the latter were obtained.
Moreover, the hypothesis presented here was not the only one, nor indeed
the first one, formulated. As is usual in such work, various hypotheses
were devised, tested, and discarded, until finally a factorial interpretation
was found that fitted fairly well all the facts known. Many results with
a bearing on plant color were obtained in other studies extending over
a period of some eight or nine years. Since the practice of the writer
is to number his pedigrees consecutively from year to year, an inspection
of the pedigree numbers, as listed in the tables, suggests at once that some
of the data presented as checks on other results could not have been
obtained after these other results. Any data applicable as a test have
been so used whether obtained for that purpose or in connection with other
studies. Whether this mode of presentation is the best one must be
left to the judgment of others. This at any rate is certain: the data could
not have been presented chronologically and discussed in relation to such
hypotheses as happened to be under test at the time any particular results
were obtained, without adding unnecessarily to the complexity of the paper.

CROSSES INVOLVING THE FACTOR PAIRS A a, B b, PI pi

Purple la x green Vic

Generations Fi and F^. — When purple plants with purple anthers
(type' la) are crossed with plants lacking all red, purple, or brown

30 R. A. Emerson

pigment, commonly known as green (type Vic), the Fi offspring are full
purple. Whether or not a quantitative determination of purple pigment
might reveal a difference, no dilution of the purple color is apparent to
the eye in the Fi plants. Four crosses of this sort with a total Fi progeny
of 111 purple plants are listed in table 1 (appendix, page 121).

Seven Fo progenies of the Fi plants recorded in table 1 are hsted in
group 1 of table 2. Fourteen other similar F2 progenies are shown in
group 2 of the same table. The Fi plants from which these fourteen F2
progenies came are not recorded in table 1 because their purple parents
were not homozygous. Some of the purple plants used as parents in
these crosses were Fi's of the original cross of purple with green. Others
were from Fi or some later generation of other crosses having the purple
type as one parent. In every case the other parent was a green plant
of type Vic. Since the purple Fi plants of these crosses were presumably
the same genotypically as the Fi's shown in table 1, their F2 progenies may
well be included tentatively with those of group 1 of table 2. Each of the
twenty-one F2 lots exhibited six distinct classes of plants with respect to
color. The 2117 plants were distributed among the six classes as follows:

Purple ®",^ ^^^^^e Dilute g ^ ^ ^

^ red purple sun red

952 305 275 91 278 216 2,117

Obviously no simple 3 : 1 mendelian behavior is in evidence here. More-
over, only four classes are expected in dihybrids where dominance is
exhibited. With dominance trihybrids ordinarily give eight classes in F2
in the well-known numerical relation of 27:9:9:3:9:3:3:1, while only
six classes were observed. Inspection of the distribution of the 2117
individuals given above, however, suggests the possibility of a 27:9:9:
3:9:7 relation, which should be realized in a trihybrid if the last three
classes were indistinguishable. A comparison of observed numbers with
those expected on this hypothesis follows:

Color types Purple ^un ™u}: ™>i^. Brown Green Total

"Observed 952 305 275 91 278 216 2,117

Calculated^ 893 298 298 99 298 232 2,118

Difference -j-59 +7 —23 —8 —20 —16 —1

3 In this and most of the following comparisons, the theoretical distributions are calculated to the nearest
whole number.

Plant Colors m Maize 31

There are rather large differences between observed and expected
numbers. The purples are considerably, and the sun reds slightly, in
excess of expectation, while each of the other four classes has too few
individuals. The probability that these deviations may be due to chance
is approximately 0.11. One might expect, therefore, to encounter chance
deviations of the magnitude observed here about once in nine such trials.
This, of course, does not substantiate the three-factor hypothesis, but
merely indicates that it is not necessarily out of keeping with the ol)servetl
facts.

Backcrosses with green Vic. — A better criterion perhaps is afforded by
the backcross of Fi purples with the green parent type. Records of such
crosses are shown in table 3. The backcrosses with F/s of table 1 are
listed in group 1, and backcrosses with similar Fi purples of other lots
in group 2. The same six phenotypcs o])served in the regular Fo generation
occurred here also. On the basis of the three-factor hypothesis and with
the assumption that there are three sorts of greens indistinguishable from
one another, the individuals of this backcross should be distril^utcd equally
to five classes with the sixth class containing three times as many indi-
viduals as any other class. The observed distribution of the 1317 indi-
viduals of the fourteen progenies is here compared with the expected

distribution:

^ , , T^ 1 Sun Dilute Dilute -o r< t. x i

Color types Purple ^.^^j purple sun red ^^'°^^ ^'»'^^" Total

Observed 170 160 176 160 172 479 1,317

Calculated 165 165 165 165 165 495 1,320

Difference +5 — 5 +11 — 5 +7 ■ — 16 ■ — 3

While a few of the backcross progenies listed in table 3 exhibit con-
siderable deviations from the expected distribution, the fourteen lots
taken together approximate it closely. The probal:)ility that the observed
deviations may be due to chance in random sampling is about 0.85.
Deviations as great as these are to be expected thru chance alone, there-
fore, in about six out of seven trials.

Workiiig hypothesis. — To the three factor pairs used to interpret the
results here reported, the symbols A a, B h, and PI pi have been assigned.
The gene A is an anthocyanin factor. In the presence of a a ordinarily
no anthocyanic pigment develops, tho brownish, or flavonol (Sando and
Bartlett, 1921), pigment may be formed. The pair Bb is named for its
2

32 R. A. Emerson

connection with the development of brown pigment, tho when both A and
B are present, sun red pigment is produced. The pair PI pi is so teraied
because of its relation to purple pigment. The phenotypic formulae as-
signed to the several classes of plant color under consideration here are

as follows:

ABPl — la, purple

AB pi — Ila, sun red

Ah PI — Ilia, dilute purple

A b pi — IVa, dilute sun red

aBPl— V, brown

aBpl —Via]

ah PI — VIb !• green

ah pi — VIcJ

Obviously the hypothesis in accordance with which the above factorial
assignments have been made is subject to several genetic tests. Naturally
the first tests to suggest themselves are studies of the behavior of the
several F2 types in F3 and later generations. Next in order are inter-
crosses between the several classes. For reasons that will appear shortly,
one of these intercrosses is here dealt with before consideration is given
to F3 generations from the several F2 classes.

Dilute sun red IVa x brown V

From an examination of the factorial assignments listed above, it is
evident that crosses of dilute sun red, A h pi, with brown, a B PI, should
produce purple Fi plants, A B PI. Moreover, these Fi purples should be
heterozygous for all three factors, AaBh PI pi, just as was assumed for
the original cross of purple, A B PI, with green, a h pi. The F2 and later
behavior of this cross should also, barring linkage, be hke that of the original
cross, so that the two can most conveniently be considered together.

Generations Fi and Fo. — The Fi generation of twenty-six crosses of
dilute sun red with brown plants is given in table 4 (page 123). The dilute
sun red parent plants were chosen from any convenient lots known to be
homozygous with respect to ^, b, and pi. The brown parent plants, on
the other hand, were from the F2 and later generations of the original
cross of purple and green or from other crosses. It was to be expected,
therefore, that some of the biown plants would be homozygous for both
B and PI, and some would be heterozygous for B, some for Pi, and some

Plant Colors in Maize 33

for both B and PI. This expectation was fully reaUzed. In group 1 of
table 4 are recorded the progenies of nine crosses with a total of 263 indi-
viduals. All but one plant of the lot were purple. The one dilute sun
red plant was presumably due to accidental pollination of the dilute
sun red mother plant. Since the dilute sun red parents of all these crosses
were A A hh pi pi, the brown parents of the crosses hsted in group 1 must
presumably have been aa B B PI PI. Similarly, the seven crosses listed
in group 2 gave purple and sun red plants only, 143 of the former and 147
of the latter. Evidently the brown parents of these crosses were aa B B
PI pi. Again, the six crosses shown in group 3 gave 105 purple, 123
dilute purple, and no other plants. The brown parents of the crosses
were therefore, presumably, aaBh PI PI. Finally, the four crosses listed
in group 4 gave 9 purple, 11 sun red, 19 dilute purple, and 17 dilute sun
red. The brown parents of these four crosses are assumed, consequently,
to have been a a B b PI pi. *'

The F2 results from the purple Fi plants of these crosses of dilute sun
red with brown are recorded in table 5. Fourteen progenies of the Fi
plants hsted in table 4 are shown in group 1 of table 5, and five progenies
from similar Fi plants not listed in talkie 4 are entered in group 2. Here,
just as with the results of the cross of purple with green (table 2), fairly
marked discrepancies between theory and observation appear when the
several progenies are taken separately. When, however, the nineteen
progenies are considered together, very close agreement is found between
observation and exjiectation, as is shown by the comparison below. The
probabihty that such deviations as are observed may be due to chance is
approximately 0.88, which means that only about once in eight trials
would as good a fit be expected. The comparison follows:

Color types

Purple

la

Observed

847

Calculated. . . .

845

DiiTerence ....

+2

Sim
red
Ila

Dilute

purple

Ilia

Dilute

sun red

IVa

Brown
V

Green
Via, b, c

Total

282

281

94

267

233

2,004

282

282

94

282

219

2,004

0—1 0 —15 +14 0

Backcrosses with green Vic. — In addition to the F2 results noted above
as derived from self-poUinated Fi purple plants, a few F, purples were back-

34 R. A. Emerson

crossed with the triple recessive green, type Vic. The records of these
crosses, seven in all, are presented in table 6. The results are. as expected,
in close agreement with the Imckcross data from the cross of purple with
green. The comparison below indicates a good fit of (calculated to observed
frequencies for the lot as a whole. The probability that such deviations
as are observed may be due to mere chance is about 0.82, indicating that
as great departures from expectation as these might be expected about
four times in five trials. The comparison follows:

Color types Purple Sun red p^j.p]g gun^red ^^'^^^ ^'^'^^^^ Total

la Ila Ilia IVa V Via, b, e

Observed 84 72 78 72 79 249 634

Calculated.... 79 79 79 79 79 237 632

Difference.... +5 —7 —1 —7 0 +12 +2

Backcrosses of la x Vic and IVa x V with IVa

Purple plants of Fi of the crosses purple x green and dilute sun red x
brown were crossed with homozygous dilute sun red stocks. On the
basis of the hypothesis used above, the Fi plants are assumed to be ^ a
B b Plpl and the dilute sun red plants A A hb pi pi. Four classes of
plants, purple, sun red, dilute purple, and dilute sun red, should be pro-
duced in equal numbers by this cross. The data are presented in table 7
(page 125). Progenies of Fi plants from the cross purple x green are listed
in group 1 and those from the cross dilute sun red x brown in group 2.
As will be seen from the comparison below, the observed numbers are in
fair agreement with the hypothesis. The probability that such deviations
as occur may be due to chance is approximately 0.67. In other words,
there are two chances in three that deviations of this sort are due to
errors of random sampling alone. The comparison follows:

Color types Purple Sun red , , Total

^^ ^ purple sun red

la Ila Ilia IVa

Observed 299 270 288 291 1 ,148

Calculated 287 287 287 287 1 ,148

Difference +12 —17 +1 +4 0

Plant Colors in Maize

35

Behavior of Fz color types in later generations

From all the foregoing it appears that the results obtained are in close
accord with the proposed three-factor hypothesis in the case of both
the cross purple x green and the cross dilute sun red x brown, and not
alone for the Fi and Fo generations but also for l)ackcrosses with green
and with, dilute sun red. It is now in order to inquire into the behavior
of these crosses in F.-s and later generations. In the presentation of the
additional data, the two crosses purple x green and dilute sun red x brown
will be considered together.

Later behavior of F2 purple la. — Purple plants of the F2 generation of
the crosses under consideration are expected to be of eight genotypes.
The expected F2 genetic formulae and the F3 color classes, together with
the relative numbers of each, are as follows:

F3 color

types

F2 genotypes

Purple
la

Smi red
Ila

Dilute

purple

Ilia

Dilute

sun red

IVa

Brown

Green
VI

\-~ A AB B PlPl

1
3
3
3
9
9
9
27

1

3

3

9

I
3

3

9

i

3

I

3

3
9

2 — A ABB PI pi

2 — A A Bb PI PI

2 — AaBBPlPl

4 — A A Bb PI pi

A — AaBB Plpl

1

A — A a Bb PI PI

1

8 — A a Bb PI pi

7

If, instead of being selfed, the F2 purple plants are backcrossed to
green of type Vic, the same F3 color classes are expected but the several
classes should, of course, be equally frequent except in case of the F2
triple heterozygotes, which should thi'ow three times as many greens as
of each of the other five types.

The F3 data from thirty-five F2 plants are recorded in table 8 (page 125).
In group 1 of the table are listed the progenies of eight selfed and one
backcrossed F2 plants. From the backcross six color types appeared
in frequencies of 4:4:11:4:4:18. The theoretical number for the first

36 R. A. Emerson

five classes is 5.6 and for the sixth class is 17. The probability that such
deviations as occur are due to chance is approximately 0.35, or more
than one in three. The eight self-polHnated plants gave together the six
types in frequencies as follows:

Color types Purple Sun red J^J|.^|^ ^^jjf^^^ Brown Green Total

la Ila Ilia IVa V Via, b, c

Observed 193 66 60 16 57 34 426

Calculated 180 60 60 20 60 46 426

Difference +13+6 0—4—3 —12 0

The probability that such deviations as occur may be due to errors
of random sampling is practically 0.27. Similar deviations might there-
fore be expected somewhat more than once in four trials. It will be
noted that two progenies lacking class IV are included in this lot (group 1,
table 8). The total number of plants in these progenies were 37 and
17, respectively, and they should therefore have had, respectively, two
and one plants in class IV.

Five Fo purple plants (group 2, table 8) gave four color types (la, Ila,
Ilia, and IVa) in F^, with total frequencies as shown below. Here the
probability, P, equals 0.75, indicating that deviations of this magnitude
might be expected thru chance in three out of four trials. The com-
parison of observed with theoretical distributions follows:

Color types Purple Sun red ^'^^^^ ^^^^^*^. Total

"^^ ^ purple sun red

la Ila Ilia IVa

Observed 102 36 29 13 180

Calculated 101 34 34 11 180

Difference +1 +2 —5 +2 0

Progenies of seven other purple F2 plants (group 3, table 8) consisted
cf the four color types la, Ila, V, and Via. Four of these F2 plants were
self-pollinated and gave a total of 164 F3 plants. Four, including one that
was also selfed, were backcrossed to green and yielded a total of 209 F3
plants. For the progenies from selfed F2 plants P = 0.20, and for those
from backcrossed plants P =^ 0.57. There is, therefore, one chance in five

Plant Colors l\ Maize

37

in the one case and considerably more than an even chance in the other

case that deviations of the kind noted may have been due to errors of
random sampUng. The comparisons follow:

Color types Purple Sun red Brown Green Total

la Ila V Via

c. ,. J /Observed 95 31 23 15 164

^^^^^"^ \ Calculated 92 31 31 10 164

Difference +3 0 —8 +5 0

Backcrossed<;^^''^''^'^^--- 54 58 44 53 209

^^^^"^"^^''^"^^ Calculated... 52 52 52 52 208

Difference.... +2 +6 —8 +1 +1

Seven self-pollinated Ff purple plants gave progenies consisting of the
four color types la, Ilia, V, and VIb (group 4, table 8). Here P = 0.75,
indicating that there are three chances in four that such deviations as are
shown are due to chance. The comparison follows:

Color types Purple IJjj.p|g Brown Green Total

la Ilia V VIb

Observed 318 114 111 42 585

Calculated 329 110 110 37 586

Difference —11 +4 +1 +5 —1

Five F2 purple plants from self-pollination gave only two color types
(la and Ila) in F3 (group 5, table 8). The total number of F3 individuals was
183, of which 139 were of color type la and 44 were of color type Ila,
the expected numbers being, respectively, 137 and 46, and the deviation
equaling 2 ± 4. One of these F> plants was also backcrossed to two greens,
resulting in 12 purple and 9 sun red F3 plants where equality of the two
classes was expected. The deviation here is 1.5 ± 1.5.

Finally, two self-pollinated Fo purple plants produced 217 F3 individuals
(group 6, table 8) of color types la and Ilia. There were 168 purple

38 R. A. Emerson

and 49 dilute piirple where the expected numbers were 163 and 54, respec-
tively — a deviation of 5 ± 4.3.

It is seen, then, that in every case the F3 progenies of F2 purple plants
were of color types expected on the basis of the three-factor hj^pothesis,
and that the F3 distributions within any group were in close agreement
with expectation. It is particularly noteworthy, however, that not all
types of F3 behavior were observed, and that the distribution of the
progenies of the thirty-five F2 plants tested was in rather imperfect agree-
ment with expectation. Thus, no Fo purple plant bred true in F3 where
one such plant was expected, and none gave progenies of pui'ple and
brown only where at least two with such behavior were expected. It
has already been pointed out (page 35) that eight classes of behavior of
Fo purples are looked for, and that any twenty-seven F2 piu'ple plants
should be distributed with respect to their F3 behavior in the relation
1:2:2:2:4:4:4:8. The actual and theoretical distributions are compared
as follows:

Observed 05205 7 79 35

Calculated.., 1.3 2.6 2.6 2.6 5.2 5.2 5.2 10.4 35.1

Difference —1.3 +2A —0.6 —2.6 —0.2 +1.8 +1.8 —1.4 —0.1

Wliile mere inspection of the above comparison might suggest poor agree-.
ment between theory and observation, nevertheless P = 0.36, indicat-
ing that such deviations as occur might be expected in more than one
out of three trials, which is not a bad fit. So far, therefore, the avail-
able data are in fair accord with the three-factor hypothesis.

Before taking up a consideration of the F3 behavior of other F2 color
types, it will be well to consider briefl}'^ the F4 behavior of F3 purple plants.
Only one F3 pm-ple of the lot having all six color types (table 8, group 1),
comparable to F2 purples, was tested in F4. This one plant gave an F4
with the four color types la, Ila, V, and Via.

Onty eight other F3 purple plants were tested in F4. All these belonged
to the lot consisting of color types la. Ilia, V, and VIb (group 4, table 8).
The F2 purple plants giving rise to this group are assumed to have been
of the genotype AaBb PI PL The Fj purple plants should therefore
have been of four genotypes and should have given F4 behavior as
follows:

Plant Colors in Maize

39

Fi color types

F3 genotypes

Purple
la

Dilute

purple

Ilia

• Brown
V

Green
Vib

1 — A ABB PI PI

1
3
3
9

i

3

1

3

2~AABb PI PI

2 — AaBBPlPl

A~AaBb PlPl

1

The data are presented in table 9. Four F4 progenies (group 1) were
made up of the four color types la, Ilia, V, and VIb. The total numbers
of plants of each of the four types, as seen below, were in close accord
with expectation, P equaling 0.57. There is more than an even chance
that such deviations as those observed may have been due to errors
of random sampling. The comparison of observed with calculated results
follows :

Color types Purple ^ .'^^ j^ Brown Green Total

la Illa V VIb

Observed 185 68 74 20 347

Calculated 195 65 65 22 347

Difference —10 +3 +9 —2 0

Three of the eight purple Fs's (group 2) gave in F4 only purple and
dilute purple plants, 88 of the former and 28 of the latter. The expected
numbers were 87 and 29, respectively, showing a deviation of 1 ±3.1.

One of the eight F3 purples (group 3) gave 67 purple and 21. brown
plants in Fj, while the expected niunbers were 66 and 22, respectively.
The deviation here is only 1 ± 2.7.

None of the eight F.-^ purples Ijred true, but only one in nine was expected
to do so. As already indicated, the theoretical distribution of nine F3
purples of the sort here under consideration, with respect to the four
kinds of behavior in F4, is 1:2:2:4. The observed distril)Ution was
0:3:1:4. There is more than an even chance that these deviations may
have been due to errors of random sampling, P equaling 0.57.

40

R. A. Emerson

It should not be forgotten that, while a very poor fit of observation to
hypothesis, as measured by values of P, throws doubt upon the correct-
ness of the hypothesis, it does not follow that a good fit proves the
hypothesis to be true. This is particularly true where small numbers
are dealt with. It will be recalled in this connection that, owing prol^ably
to the small numbers tested, no F2 purple has been found to breed true in
F3 and none has been found to give only purple and brown offspring.
It has been shown, however, that purple plants of the genotype
A a B B PI PI exist, since one F3 purple threw only purple and brown
plants in F4. Moreover, one of these F4 purples repeated this behavior
in F5. Similarly it can be said that purples of the genotype A A B B PI PI
have been recovered from the crosses under consideration, for two F4
purple plants of the lot composed of purples and dilute purples (group 2,
table 9), when backcrossed to green, gave 18 purple plants and no other
types in the next generation, and one of these two F4 purples, when crossed
back to dilute sun red, gave 34 purple plants. Two other purples of
the same F4 lot, when similarly crossed, gave both purple and dilute pm*ple,
23 of the former and 18 of the latter. Pm'ple plants of all the expected
genotypes have therefore been recovered in one or another generation
from F2 to F4 from the original crosses of purple x green and dilute sun
red X brown. Moreover, these genotypes have been found in numbers
not far from what might reasonably be expected considering the relatively
small numbers tested. It now remains to inquire into the F3 and later
behavior of F2 color types other than purple.

Later behavior of F2 sun red Ila. — Sun red plants of F2 of the crosses
purple x green and dilute sun red x brown are expected, in accordance
with the three-factor hypothesis, to be of four sorts with respect to their
behavior in F3, as follows:

F2 genotypes

F3 color types

Siin red
Ila

Dilute

sun red

IVa

Green
Via, c

1 — AABBplpl.

2 — AABbplpL
2 — AaBBplpl.
4 — A a B bplpl.

Plant Colors in Maize 41

Only nine Fo sun red plants wore tested by their F3 behavior, and no
later generations were si'own. All the available data ara {jfiven in table
10 (page 128). Five F2 plants, when self-pollinated (group 1 of the table),
gave the expected three classes of progeny, sun red, dilute sun red, and
green, with a distribution of the F3 plants as given below, and in addition
a single brown plant. To include this unexpected plant in the compari-
son with the calculated distril)ution would give zero as the value of P,
which is equivalent to saying that even in an infinite number of trials there
is no chance of finding such a plant thru errors of random sampling. The
single off-type plant is readily accounted for by supposing that a grain of
foreign pollen was accidentally admitted in the pollination of the parent
plant. Tho it is realized that, with such a convenient supposition always
at hand, almost any result can be made to fit a theory, the reality of just
such accidental pollinations will not be questioned ,by any one who has had
experience in the technique of maize pollination. With the elimination
of this one plant, the fit of observation to hypothesis is almost perfect.
The comparison follows:

Color types Sun red ^^^^^^ Green Total

Ila IVa VIa,c

Observed 126 42 55 223

Calculated 125 42 56 223

Difference +1 0 " —1 0

Three Fo sun red plants, including one of the five in the former test,
were crossed back to green (group 1, table 10). The same three color
types w^ere observed as in the self-pollinated plants, with the addition
again of a single off-type plant, this time a purple one. Even if this plant
is left out of consideration as due to an accidental pollination, the fit of
observed with calculated numbers is not very good. Such deviations
from theoretical behavior are to be expected thru chance alone only once
in eight trials, P equaling 0.12. The comparison follows:

Color types Sun red ^^^^ ^.^^ Green Total

Ila IVa Via, c

Observed 14 18 50 82

Calculated... 20.5 20.5 41 82

Difference —6.5 —2.5 +9 0

42

R. A. Emerson

A single F2 sun red plant (group 2, table 10) gave, from self-pollination.
23 sun red and 9 dilute sun red F3 plants, a deviation fronri expectation of
1 ± 1.7.

A single Fo sun red plant (group 3, table 10), when crossed with green
Vic, gave 50 sun reds and 43 greens where equality was expected, a devia-
tion of 3.5 ± 3.3.

By way of summary of the behavior of Fo sun red plants, it must be
noted that, while four sorts of behavior were expected, only three sorts
were observed. While any nine such F2 plants should be distributed with
respect to the four kinds of behavior in the relation 1:2:2:4, the observed
relation was 0:1:1:7. Wliile mathematically this is not a very bad fit
considering the small numbers involved, P equaling 0.24, it is inadequate
for a deteiTQination of the possible genotypes of F2 sun red plants.
Fortunately, certain crosses considered later (page 51) involving the sun
red type, with presumably the same genetic constitutions as the F2 sun
reds of this cross, afford a more nearly adequate test of the matter.

Later behavior of Fo dilute purple Ilia. — F2 dilute purple plants should
present the same types of behavior in F3 as F2 sun reds, but, of course,
with somewhat different color types appearing, as follows:

F2 genotypes

1— A Abb PI PI
2~AAbbPlpl.
2 — A abb PI PL
4~ A abb PI pL.

F3 color types

Dilute

purple

Ilia

Dilute

sun red

IVa

Green
VIb, c

The available data from this test are given in table 11 (page 129). Four
F2 dilute purples (group 1) yielded the three color types expected, dilute
purple, dilute sun red, and green, in the numbers shown below. There
is considerably more than an even chance that the deviations from expecta-
tion may be due to errors of random sampling, P equaling 0.58. The
comparison follows:

Plant Colors in Maize 43

r^ 1 J. Dilute Dilute ri n. . ■,

C«^o^-*yP^^ purple sun red ^'''''' ^^^^^

Ilia IVa VIb, c

Observed 95 31 50 176

Calculated 99 33 44 176

Difference —4 —2 +6 0

One of the dilute purple Fo plants used in this test was backcrossed
with green VIc (group 1, table 11), with the result shown below. There
is practically an even chance that the observed deviations may be due to
errors of random sampling, P equaling 0.49. The comparison follows:

^ 1 , Dilute Dilute ^ t- ^ i

Color t\T3es i , ureen Total

■^^ purple sun red

Illa IVa VIb, c

Observed 21 25 57 103

Calculated 26 26 52 104

Difference — 5 — 1 +5 — 1

One F2 dilute purple gave 57 dilute purple and 21 dilute sun red plants
in Fa (group 2, table 11). The expected numbers were 58.5 and 19.5,
respectively, the deviation being 1.5 ± 2.6.

Three Fo dilute purples gave a total of 85 dilute purple and 20 green
plants (group 3, table 11), the theoretical numbers being 79 and 26,
respectively. The deviation from expectation, 6 plants, is just twice the
probable error.

One F2 dilute purple bred true in F3, producing 21 dilute purple plants
and no other types (group 4, table 11). Thus, all the sorts of behavior
expected of F2 dilute purples were reahzed in F3. The distribution of
the F2 plants with respect to the four sorts of behavior was 1:1:3:4,
instead of the theoretical distribution 1:2:2:4. Differences of this sort
might be expected thru chance in four out of five trials, P equaling 0.80.

Only three plants of these lots were tested in F4. One was a dilute sun
red of the lot made up of dilute purples and dilute sun reds, and this one
bred true in Fi as was expected of it, producing 34 dilute sun red plants.
The other two plants tested further were dihit(,' purples of the lot contain-
ing the three color types III, IV, and VI. Both again gave these three

44

R. A. Emerson

types, the total numbers of the respective classes being 29, 5, and 18.
The expected numbers, 29, 10, and 13, show a deviation from expecta-
tion which might result thru chance about once in nine trials, P equaUng
0.11.

Later behavior of F^ dilute sun red IVa.—z Dilute sun red plants of F2
should be of two sorts, A Ahhplpl and Aahhpl j)l. Five such plants
were tested, with results as shown in table 12 (page 129). Of these five,
two bred true, producing a total of 92 dilute sun red plants (group 2).
One of these two, when backcrossed with green, gave 69 dilute sun red
plants. Three of the five F2's gave in F3 dilute sun reds and greens, 62
of the former and 17 of the latter (group 1). The theoretical numbers
were 59 and 20, respectively. The deviation of 3 plants is only a httle
greater than the probable error, ± 2.6. With two of the F2 dilute sun red
plants breeding true and three again throwing segregates, expectation
was very nearly reahzed.

Later behavior of F2 brown V. — Brown plants of Fo are expected to be
of four genotypes and to show consequent differences in behavior in F3
as follows:

F3 color types

F2 genotypes

1 — aaBBPlPl

2 — aaBB Plpl.
2 — aaBbPlPl.
4 — aaBbPlpl..

Data for F3 from fourteen F2 brown plants are presented in table 13
(page 130). Five self-pollinated F2 browns (group 1) gave, in addition
to one sun red prcsumabl}'- due to accidental pollination, 96 browns and
74 greens in F3, which is almost exactly a 9 : 7 relation, the deviation being
0.4 ± 44. Nine other selfed F2 browns (group 2) gave in F3 a total of 354
brown and 104 green plants. An exact 3 : 1 ratio for the total of 458
would be 343.5 and 114.5, respectively, the deviation being 10.5 ± 6.3.
Such a deviation might be expected thru chance alone about once in four

Plant Colors in Maize 45

trials. One of the F2 brown plants that, when solfod, gave a 3:1 ratio
in F3, when crossed with green gave 34 brown and 41 green plants where
equal numbers were expected, the deviation being 3.5 ± 2.9. None of
the fourteen F2 brown plants bred true in F3. The fourteen plants should
theoreticall}^ have given F^ ratios of 1:0, 3:1, and 9:7 in approximately
the respective numbers of 1.6, 6.2, 6.2, while the observed numbers were
0, 9, 5. Such deviations might occur by chance once in five trials, P
equaUng 0.22.

It is often difficult and sometimes practically impossible from ordinary
F3 progenies to distinguish between the two genotypes of brown which
throw 3:1 progenies,, namely, a a B B PI pi and ao B b PI PI. The green
plants thrown b}^ the former often show some brown pigment in the exposed
parts of the sheaths and husks (type Via), a condition not seen in the
greens (\Tb) thrown ])y the latter. In some lots the brown pigment
is fairly conspicuous but in others it is very weak or is absent. Again, the
greens of type VIb thrown by l^rowns of the genotype aaBb PI PI
show considerable brown in the glumes of the staminate flowers. This
is particularly pronounced when r<^'' (a gene for cherry pericarp which is
effective only in the presence of PI) is present, but when this factor is
lacking the brown color is often so faint that it is impossible to distinguish
between a green plant carrying PI and one lacking it. If r'''' is present,
the greeu plants carrjnng PI develop a Ught brownish pericarp at maturity
while those lacking PI never show this pericarp color whether or not B
is present. Here again, however, the hght brownish pericarp due to
r^^, PI, and a a ma}^ be wholly masked if there happens to be present
another pericarp color gene, P, which with a a brings about a strong
brown color of the pericarp whether or not PI or B is present.^ On the
whole, therefore, it is difficult, and often impossible, to determine the
genotype to which a brown plant belongs, by an inspection of the green
plants occurring in its progen3^ Because of this, the 3 : 1 lots of F3
progenies of Fo brown plants are lumped together in group 2 of table 13
without any attempt to separate them into the two classes expected.
Fortunately, it is readily possible to distinguish between brown plants of
the two genotypes under consideration here by means of appropriate
crosses.

* An account of these pericarp-color factors is to be published later by Dr. E. G. Anderson, who is
making a study of the pericarp colors of maize.

46

R. A. Emersox

When brown plants of all the genotypes expected in F2 of the crosses
of purple X green or dilute sun red x brown are crossed with homozygous
dilute sun red plants, the following behavior is expected in the next
generation :

F2 genotypes

1—aaBB PlPl
2~aaB B Plpl.
2^aaBb PlPl.
4 — aaBb Plpl.

Purple
la

F2 X A Abb pi pi

Sun red
Ila

Dilute

purple

Ilia

Dilute

sun red

IVa

A few such tests of F2 brown plants are recorded in table 14. Two plants
(group 1), on being crossed with dilute sun reds, gave purples and sun
reds only, 38 of the former to 45 of the latter, where equality was expected,
the deviation being 3.5 ± 3.1. One of these plants has progeny from self-
pollination listed in table 13, in group 2, the 3:1 lot. This plant was
expected, of course, to throw only two color types from the cross with
dilute sun reds, for otherwise it should not have given a 3 : 1 progeny on
being selfed. The two brown plants in group 1 of table 14 must have
been aa B B Plpl. Two other F2 brown plants (group 2) gave 32 purple
and 38 dilute purple instead of the equal numbers expected, the deviation
being 3.0 ± 2.8. These plants are assumed to have been a a B b PI PL
A single F2 brown plant (group 3) when crossed with dilute sun red gave
15 purple plants, and is therefore assumed to have been a a B B PI PI.
The behavior of several F3 brown plants when crossed with dilute sun
reds is also shown in table 14. Three of these plants were from 9:7 F3
lots and therefore are presumably comparable with F2 browns. One of
these three (group 4) gave the four color types I to IV in the numbers
1:2:6:3. It was probably a a Bh Plpl and should have given a 9:7
progeny if it had been selfed. The other two F3 browns of the 9:7 lot
gave 49 purple plants (group 7) and are consequently regarded as
aaB B PI PL All the other F3 brown plants tested were from the

Plant Colors in Maize 47

3:1 lot listed in table 13, group 2. None of these should give more than
two types when crossed with dilute sun red. One gave 46 purple and
1 dilute sun red (group 7), the latter doubtless from an accidental
poUination of the dilute sun red mother plant. Two F3 browns gave 22
purple and 24 sun red plants (group 5), and four produced 73 purple and
85 dilute purple plants (group 6).

To summarize, all the theoretically possible genotypes of brown plants
have been found either in F2 or in such F3 lots as showed a 9:7
ratio of brown to green. Since these Fs's are comparable with F2 browns,
thej^ maj^ be added to the F2's in this summary. Of the twenty-one
brown plants thus grouped, the numbers found to belong to each geno-
tj^pe are compared below with the calculated numbers. The deviations
are such as might be expected to occur once in three trials, P equaling
0.34. The comparison follows:

aciBBPl j)l
aaB B PI PI or a a B h PI pi Total

aaBbPl PI

Observed 3 12 6 21

Calculated 2.3f+) 9.3(+) 9.3(+) 21

Difference +0.7(-) +2.7(-) — 3.3(+) 0

Later behavior of F2 green VI. — All Fo green plants should breed true
phenotypically in F3. Data from eight such F3 progenies are given in
table 15, group 1 (page 132). There were observed a total of 179 green
plants, and no other tjq^es. Progenies of sixteen green plants of the
F2 lots listed in tables 3 and 6 (pages 122 and 124), produced l^y backcrossing
Fi purples to greens, are given in table 15, groups 2 to 5. The total
number of green plants in these progenies is 311. A single brown plant
found in one of these progenies is assumed to have been due to acci-
dental pollination. Green plants are thert'fore found to breed true green
as expected, but there is nothing in this fact to indicate that green plants
of the crosses under consideration are genotypically alike. That the
five genotypes expected on the basis of the three-factor hypothesis were
present among the progenies hsted in table 15 is demonstrated in the
next section of this paper.

48 R,. A. Emerson

Intercrosses of F^ color types

It has been shown in the preceding pages that all the six color tj^pes
occurring in F2 of a cross between purple and green behave in F3 and later
generations as is expected on the basis of the three-factor hypothesis
suggested to account for the F2 results. It remains to determine whether
the several color types behave in accordance with the hypothesis when
intercrossed one with another. Of the fifteen possible intercrosses between
phenotypically different types, two have already been discussed. The
cross of purple with green has formed the basis of the whole discussion.
The cross of dilute sun red with brown, since it was expected to give the
same results as the original cross of purple with green, was most conven-
iently considered with that cross in generations later than F2. The results
of this second cross have been in accord with expectation. The other
thirteen intercrosses are now to be considered, together with intercrosses
of some types that are phenotypically alike.

Dilute sun red IVa x green Via. VIb, Vic. — The progenies of self-
pollinated green plants were listed in table 15 in several groups in
accordance with what was learned of their genotypic constitution by the
crosses to be considered here. The regular F3 lots, from self-pollinated
F2 greens of self-pollinated Fi purples, were put in group 1 of table 15.
Only one of the same F2 greens (table 16, group 2) was crossed with homo-
zygous dilute sun red, A Ahhpl pi. The result was 67 dilute purple
plants. Another green plant, an F3 from a self-pollinated F2 green, gave,
when similarly crossed, 9 dilute purple plants (group 2). Evidently both
these green plants were a abb PI PI. Four other F3 green plants, when
crossed with dilute sun red, gave a total of 148 sun red plants (group 1,
table 16). One of these four belonged to an F3 lot containing browns and
greens in a 3:1 relation, and could not, theoretically, have done other
than give all sun red or all dilute purple when crossed with dilute sun red.
Two of the four were from greens of an F3 lot made up of purples, sun reds,
browns, and greens, and were therefore assumed to be aa B B pl pl,
as the crosses with dilute sun red showed them to be. One of the four
green plants, however, belonged to an F3 lot of browns and greens in a
9:7 relation and was consequently comparable to an F2 green. A sixth
F3 green also belonged to a 9 : 7 lot, comparable to an F2 lot. When crossed
with dilute sun red (group 3, table 16), it gave 24 dilute sun red plants,

Plant Colors in Maize 49

and is therefore assumed to have been a abb yl pi. All three of the
theoretically possible homozygous genotypes have therefore been demon-
strated among the Fo greens or among Fs's comparable to F2's.

In addition to the green plants of the direct Fo and F.s generations,
noted above, fifteen other greens were crossed with dilute sun red. All
these greens belonged to a single progeny, 2019, which was the result of a
backcross of an Fi purple with a green, a abb pi pi (table 3, group 1).
All of them should therefore have been heterozygous for B or PI, or have
lacked these dominant genes. Seven of the fifteen, when crossed with
dilute sun red, gave 110 sun red and 85 dilute sun red plants (group 4,
table 16), a deviation from equality of 12.5 ± 4.7. The green parent
plants are consequently regarded as a a B b pi pi. Five others of the
fifteen green plants (group 5) gave a total of 50 dilute purple and 65
dilute sun red, a deviation from equality of 4.5 ± 3.7, and hence are assmned
to have been a abb PI pi. Three of the fifteen (group 6) gave a total of
106 dilute sun red plants. These three must, it is supposed, have been
a abb pi pi.

Naturally, in the course of the writer's maize studies, many other
crosses between green and dilute sun red have been observed. But no
purpose can be served by presenting here all this mass of data. Much
of it has accumulated in connection with a study of the interrelations of
plant and aleurone color, and will find its appropriate place in a later
publication on that topic. A few Fo and backcross progenies of dilute sun
red Fi's of such ciosses are, however, listed in table 17 (page 134), to serve
as an indication of the behavior of all. Three F.; progenies (group 1, table
17) contained 269 dilute sun reds and 99 greens, a deviation from the
expected 3: 1 ratio of 7 ± 5.6. Five progenies of Fi dilute sun reds back-
crossed to green Vic (group 2) included 357 dilute sun reds and 358 greens,
a deviation from the expected 1 : 1 ratio of only 0.5 ± 9.0.

The behavior of a number of the sun red and dilute^ purple plants listed
in table 16 has been studied in F2 and later generations. Consideration
of this later behavior is conveniently deferred to a later section of this
paper (pages 51 and 53), where it is taken up with other crosses which
should theoretically give similar results.

Green x green. Via, VIb, Vic. — A number of green plants of progcMiy
2019, discussed above, were intercrossed. That these green plants l)rcd
true green when selfed was shown by the records of table 15 (groups 3

50 R. A. Emerson

to 5) . That they were of three distinct genotypes was shown by the data
recorded in table 16 (groups 4 to 6). The behavior of random intercrosses
of the same green plants is now to be considered. The data are given in
table 18.

The green plants that served as parents of the crosses listed in group
6 of table 16, it was decided, must have been a a bbpl jd. When such
plants are crossed with green plants of any of the other genotypes, nothing
but green plants should result. A single cross of one of these greens with
a green of the constitution a a B b pi pi (table 16, group 4) gave 23 green
plants (table 18, group 1) as expected. Another cross of one of these
greens with a green of the genotype a abb PI pi (table 16, group 5) gave
22 green plants (table 18, group 2). Crosses of green plants belonging
to like genotypes should, of course, give only green plants. Three crosses
of plants shown to be a a 5 6 pi pi (table 16, group 4) gave 72 green plants
(table 18, group 3) . A single cross between plants shown to be a ah
b Pi pi (table 16, group 5) gave 24 green plants (table 18, group 4). Five
crosses of plants of genotype a a B b pi pi with plants of genotype
a abb PI pi gave a total of 40 brown and 105 green plants (table 18,
group 5). Here a 1:3 ratio of brown to green is to be expected. The
theoretical numbers are therefore 36 and 109, respectively, and the devia-
tion is 4.0 ± 3.5. The important fact here is that all these intercrosses of
greens gave the color types expected on the basis of the results of crosses
of the same individual green plants with dilute sun reds. The writer
deems himself fortunate in having been able to obtain results approxunat-
ing so closely a complete demonstration of the several genotypes of
green, since the selfing, the crossing with dilute sun reds, and the inter-
crossing of greens, were made at the same time, with the green plants
chosen wholly at random.

Brown V x green Vic. — When brown plants are crossed with green
plants of type Vic, the Fi plants arc brown, and browns and greens alone
appear in F2. Since brown is supposed to be a B PI and type Vic green
a b pi, the F2 progenies should exhibit 9 : 7 ratios. Eleven F2 progenies
are listed in table 19 (page 135), with a total of 317 brown and 223 green
plants. The theoretical numbers are 304 and 236, respectively, showing
a deviation of 13 ± 7.8. There is more than one chance in four that such
a deviation is due to errors of random sampling, P equaling 0.27.

Plant Colors in Maize 51

Of any nine F2 brown plants of this cross, theoretically one should
breed true in F3, four should give a 3:1 ratio, and four should give a 9:7
ratio. Six F^'s were tested, with the results shown in table 20. Two
bred true, with a total of 29 brown plants (group 1). Two gave ratios
classed as 3:1, the totals (group 2) being 100 brown to 40 green, a devia-
tion of 5.0 ± 3.5. Two gave progenies interpreted as 9:7 (group 3),
totaling 39 l)rown and 39 green, the deviation being 5.0 ± 3.9. Of the
3:1 Fs lot, two browns bred true in F4, producing 59 brown plants, and
one green l^red true, producing 56 green plants.

The distribution of the F2 brown plants with respect to their F3 behavior
— two breeding true, two throwing a 3:1 ratio, and two a 9:7 ratio —
was as near expectation, 1:4:4 in nine, as could perhaps be expected from
such small nimibers. If these six F2 browns are combined with the four-
teen F2 browns of the original cross of purple x green noted earlier in this
paper (page 44), a very good fit of the hypothesis and observation is found
(z2 = 0.88). Theoretically these two lots of F2 browns should be of the
same genotypes, so that they may well be so combined. The comparison
follows :

F3 ratios 1:0 3:1 9:7 Total

Observed 2 11 7 20

Calculated 2 9 9 20

Difference 0+2 —2 0

Sun red II a x green Vic— When both parents are homozygous, the
cross of green of type Vic with sun red results in sun red plants only.
Three such crosses gave 112 sun red plants. Crosses with heterozygous
sun red plants gave Fi progenies of sun red together with dilute sun red
or green or both, depending presumably upon whether one or the other
or both of the factors A and B were heterozygous. Fi sun red plants of
such crosses are presumed to have the formula AaBhpl-pl, and should
therefore produce in F2 the three color types sim red, dilute sun red, and
green, in the relation 9:3:4. Sixteen F2 progenies of such crosses are
listed in table 21, group 1 (page 136). It has already been shown (page
48) that crosses of some green plants, a B pi, with dilute sun reds, A h pi,
give sun red Fi offspring, which are also assumed to be A a Bh pi pi.
Five F2 progenies of such crosses are, for convenience, considered here

52 R. A. Emerson

(group 2, table 21) with the crosses of sun red and green. While certain
of the individual progenies, due perhaps to the small numbers concerned,
deviate considerabl}^ from the expected results, the twenty-one progenies
(groups 1 and 2, table 21) taken together approach so closely to expectation
that there is more than one chance in four that the observed deviations
may be due to errors of random sampling, P equaling 0.28. The com-
parison of observed with expected numbers follows:

Color types Sun red g^^j^^Vg^i Green Total

Ila IVa Via, c
Observed :

Ila xVIc 827 268 383 1,478

IVa X Via 343 120 179 642

Total 1,170 388 562 2,120

Calculated 1,193 398 530 2,121

Difference —23 —10 +32 —1

Fi sun red plants, A a B h pi pi, were also backcrossed with green plants
of type Vic, a b pi. Fifteen progenies of these backcrosses are listed in
table 21, the progenies from the cross Ila x Vic in group 3 and those from
the cross IVa x Via in group 4. The expected relation of 1:1:2 was
realized fairly well in the results, the odds against the observed devia-
tions' being due to chance being about three to two, P equaling 0.39.
The observed and expected results are compared as follows:

. Color types Sun red ^^"^^^^ Green Total

Ila IVa Via, c
Observed :

(Ila x Vic) X Vic 134 123 267 524

(IVa X Via) X Vic 442 465 962 1 ,869

Total 576 588 1 ,229 2 ,393

Calculated 598 598 1 .196 2 ,392

Difference —22 —10 +33 +1

Plant Colors in Maize 53

Dilute purple Ilia x green Vic. — Since dilute purple differs from sun
red merely in having the dominant PI factor instead of B, crosses of dilute
purple with green of type Vic should behave just as did the crosses con-
sidered in the preceding section, except that dilute purples take the place
of sun reds in the progeny. Eight crosses of dilute purple with green of
type Vic resulted in 91 dilute purple plants. The F2 results of these
crosses are given in table 22, group 1. Since the Fi plants of these crosses
are assumed to have been A ah b PI pi, the F2 results should be the same
as those expected from crosses of greens of type VIb with dilute sun reds.
The Fi's of the latter crosses have already been discussed (page 48). The
F2 results, six progenies, are for convenience considered here (group 2,
table 22) . "Wliile the expectation of a 9 : 3 : 4 relation was not very closely
realized in the ol)served results, such deviations as those found might be
expected thru chance about once in eight trials, P equaling 0.13. The
comparison of observed and expected distributions follows:

Color types ^^^ ^ G.een Total

Ilia IVa VIb, c
Obsei'ved :

Ilia X Vic 416 149 173 738

IVa x VIb 274 102 107 483

Total 690 251 280 1 ,221

Calculated 687 229 305 1,221

Difference +3 +22 —25 0

A single Fi plant backcrossed with green gave the same three color types
in the relation 26:20:56. The theoretical distribution is 25.5:25.5:51.0.
Deviations of the observed order might be expected somewhat more than
twice in five trials, P equaling 0.44.

Seven F2 greens bred true in F3 with a total of 359 individuals. One
dilute sun red F2 plant bred true with a progeny of 156 dilute sun red
plants. Of the F2 -dilute purples, some bred true, some threw the three
types seen in F2, some gave only dilute purple and dilute sun red, and
some gave only dilute purple and green. Notwithstanding the rather
poor fit in F2, therefore, the fact that practically all the expected .classes

54 R. A. Emerson

of behavior were exhibited in F3 makes it seem Ukely that the deviations
in F2 were due mainly to chance.

Sun red II a x brown V. — A single cross of brown with sun red gave
purple plants only, as was expected. Since both parents were homozygous,
all the Fi plants should have been of the genotype Aa B B Plpl and
should have produced in F2 the four types purple, sun red, brown, and
green, in the relation 9:3:3:1. The three F2 progenies of this cross are
recorded in table 23 (page 137). The expected color types were produced
in approximately the expected numbers. The odds against the observed
deviations' being due to chance are three to two, P equaling 0.40. A
comparison of observed with expected distributions follows:

Color types Purple Sun red Brown Green Total

la Ila V Via

Observed 120 29 37 10 196

Calculated 110 37 37 12 196

Difference +10 —8 0 —2 0

Purple la x brown V . — Crosses of brown with purple gave purple
Fi's, and four F2 progenies gave a total of 116 purple and 38 brown plants,
which is very near the 3:1 ratio expected from Fi plants of the genotype
A a B B PI PI, the deviation being 0.5 ± 3.6. Nine Fi purples backcrossed
to browns gave progenies totaling 484 purple and 477 brown plants, a
deviation from the expected equality of 3.5 ± 10.5.

Purple la x sun red Ila. — Purples and sun reds should differ by a
single factor pair, PI pi. The Fi purples backcrossed to sun red should
give a 1 : 1 ratio of the parental types. Five such backcrosses gave 47
purple and 57 sun red plants, a deviation from expectation of 5 ± 3.4.
No progenies of selfed Fi's were observed.

Purple la x dilute purple Ilia. — Purples are assumed to differ from
dilute purples by the factor pair B b. Six Fi purples backcrossed with
dilute purple gave 40 purple and 52 dilute purple plants. This is a
deviation from the expected equaUty of 6 i 3.2. No other tests of the
cross of purple x dilute purple were made.

Sun red Ila x dilute sun red IVa. — Sun reds and dilute sun reds should
differ in one factor pair, B b, and should therefore give a simple 3 : 1 result
in F2. The Fi generation of six crosses of these color types consisted
of 135 sun red plants. Sixteen F2 progenies Hsted in group 1 of table 24

Plant Colors in Maize 55

(page 138) totaled 998 sun rod and 314 dilute sun red, a deviation from
the 3:1 ratio of 14 db 10.6.

Fourteen backcrosses of Fi sun red plants with dilute sun reds (group 2,
table 24) resulted in 811 sun reds and 742 dilute sun reds, a deviation
from the expected equality of 34.5 13 ±.3.

Two F2 dilute sun reds bred true in F3 as expected (table 25, group 1),
with a total of 50 dilute sun red offspring. Two F2 sun red plants (group 2)
gave a total of 19 sun reds in F3, and a third F2 plant, on backcrossing
with dilute sun red, gave 101 sun reds. Four other F2 sun red plants
gave both sun reds and dilute sun reds in their F3 progenies (group 3),
the respective numbers being 373 and 127; the calculated numbers are
375 and 125, respectively, showing a deviation of 2 ± 6.5. Of the seven
F2 sun reds tested, four were heterozygous and three apparently
homozygous for the B factor. On the whole, therefore, the crosses of
sun red with dilute sun red behaved approximately as expected.

Dilute purple Ilia x dilute sun red IV a. — Five crosses of dilute sun
red with dilute purple gave a total of 344 Fi plants, all dilute purple.
Since these Fi's are supposed to be heterozygous for the PI factor only,
a 3:1 Fo distribution of color types should result. Seven F2 progenies
Usted in group 1 of table 28 (page 139) had a total of 261 dilute purple
and 87 dilute sun red plants, exactly a 3:1 relation. Five Fi plants were
backcrossed with dilute sun red (group 2) and resulted in 275 dilute
purples and 263 dilute sun reds. The deviation from the theoretical 1 : 1
relation is 6 ± 7.8.

Only two F2 dilute purples were tested by their F3 behavior. Neither
bred true, the total produced being 38 dilute purples to 17 dilute sun reds,
a deviation from the 3:1 ratio of 3.3 ± 2.2. As far as they go, then,
the results are in close agreement with what is expected of the crosses
here under consideration.

Sun red Ila x dilute purple Ilia. — Theoretically, crosses of sun red,
A B pi, with dilute purple, A b PI, should give purple, A B PI, in Fi.
Two crosses, as shown in group 1 of table 27 (page 140), gave a total of
24 purple and no other types. Here the parents were doubtless
homozygous. If one or the other of the panMits is heterozygous^ two
color types are to be expected in Fx. A single cross (group 2. table 27)
gave 74 purple and 75 sun red plants. Such a result is to l)e expected when
the sun red parent is homozygous, A A B B pl pi, and the dilute purple
parent is heterozygous, A Abb PI pl. Two other crosses (group 3) gave

56 R. A. Emerson

a total of 28 purple and 29 dilute purple plants. The parents are therefore
assumed to have been A A B h pi pi and A A hb PI PI, tho the same
results should have been obtained if one or the other, but not both,
of the parents had been A a. The important point here is that purple
plants were produced in all crosses, showing that sun red and dilute purple
carry complementary factors for purple. The factors are assumed, in
keeping with the hypothesis under test, to be B and PI.

In accordance with this hypothesis, the Fi purple plants should be
A A B b PI pi and should throw four color types in F2. No direct F2
progenies have been observed^ but seven progenies from backcrosses
of Fi purples with dilute sun reds are recorded in table 28. While the
deviations from the expected equality among the four classes are rather
large, they are not greater than might occur by chance about once in
four trials, P equaling 0.26. The comparison follows:

Color types Purple Sun red ^^^"l"" ^'^^'^^ Total

''^ ^ purple sun red

la Ila Ilia IVa

Observed 99 110 104 83 396

Calculated 99 99 99 99 396

Difference 0 +11 +5 —16 0

Purple la x dilute sun red IVa.— Crosses of purple with dilute sun red
should give purple Fi plants, A A B b PI pi, and 9:3:3:1 F2 progenies.
Four such crosses resulted in 65 purple plants in Fi. The F2 results are
reported in table 29, group 1. The distribution of the individuals of the
twenty-six progenies taken together is shown below in comparison with
the calculated distribution. The four color types expected were observed
in approximately the expected numbers. Deviations such as shown might
be expected thru chance about twice in eleven times, P equaling 0.18.

Color types Purple Sun red ^'*"f^ ^^^"*^, Total

•^ ^ ^ purple sun red

la Ila Ilia IVa

Observed 1 ,013 316 • 296 100 1 ,725

Calculated 970 323 323 108 1 ,724

Difference +43 —7 —27 —8 +1

Plant Colors in Maize 57

Some of the Fi purple plants were crossed back to dilute sun red, with
results as given in group 2 of table 29 and sumnmrized below. The
seventeen progenies together approached the expected equality of the
four color types so closely that the observed deviations might be expected
thru chance more than twice in five trials, P equaling 0.44.

Color types Purple Sun red ^^^^^^ ^^^"^^, Total

•^ ^ ^ purple sun red

la Ila Ilia IVa

Observed 323 306 325 289 1 ,243

Calculated 311 311 311 311 1,^4

Difference +12 —5 +14 —22 —1

Sixteen Fo purple plants were tested b}^ their Fs progenies (table 30).
Seven F2 purples (group 1) gave again the four color types purple, sun
red, dilute purple, and dilute sun red, the several classes being I'epresented
by 268, 105, 78, and 28 individuals, respectively, while the calculated
numbers were 269, 90, 93, and 30. The odds against such deviations
being due to chance are about three to one, P equaling 0.24. One of the
seven F2 purple plants was crossed with green a abb pi pi and gave the
same four classes of progeny, represented by 26, 25, 24, and 21 plants,
respectively. Evidently these F2 purples were like the Fi's, A A Bb PI pi.

Four other F2 purples (group 2, table 30) gave only purple and sun
red progenies. Three of these when sclfed gave 60 purple and 22 sun red.
Two of these three and one other, when backcrossed with dilute sun red
or green, gave 32 purples and 31 sun reds. The four F2's are therefore
regarded asAABBFl pl.

Five F2 purples (group 3) gave purples and dilute purples only. Four
of these, which were selfed, gave 162 purples and 48 dilute purples, while
the fifth, which was backcrossed to dilute sun red, gave 17 purples
and 15 dilute purples. These five F2's are consequently regarded as
AABb PI PI.

None of the sixteen F2 purples tested bred true in F.-), A A B B PI PI.
A single? F3 purple (group 6), however, which occurred in the ¥i lot showing
the four color tj^pes (group 1) and which was therefore comparable to
the F2 purples, Ijrcd true in Fi, pi-oducing 69 purples on being selfed and
18 on being backcrossed to green. Of three other F3 purples of the same

58 R. A. Emerson

Fs lot, two (group 4) gave only purples and sun reds, and one (group 5)
gave only purples and dilute purples.

The twenty .Fo and Fs purples tested, therefore, were distributed with
respect to the four kinds of behavior in the relation 7:6:6:1, in contrast
to the calculated distribution of approximately 8.9:4.4:4.4:2.2. There is
more than an even chance that such a difference may be due to errors
of random sampling, P equaling 0.53. On the whole, therefore, the F2
purples of this cross behaved in later generations as was expected of
them.

F2 sun red plants of the cross purple x dilute sun red showed two types
of behavior in F3 (table 31, group 1). Three Fo's bred true, with 53 sun
red plants in F3. Four gave a total of 70 sun red and 24 dilute sun red
plants. Where an expected ratio of one true breeding to two segregating
progenies was expected, the observed relation of three to four is not a bad fit.

F2 dilute purples also showed the two types of behavior expected in
F3 (group 2, table 31). Three bred true, with a total of 97 dilute purple
plants, and six gave a total of 217 dilute purple and 86 dilute sun red
plants. The 1:2 ratio was therefore exactly realized.

Three F2 dilute sun reds bred true in F3 (group 3) as was expected
of them, producing a total of 72 dilute sun red plants.

Numerous F3 plants of the several color types of the cross under con-
sideration here were tested by F4 and F5 progenies, with results wholly
consistent with expectation. It is deemed unnecessary to give the records
of these later generations in detail.

Evidence from aleurone-color and linkage relations
The evidence presented up to this point in support of the three-factor
hypothesis, involving A a, Bh, PI pi, has had to do .with the behavior
of the several F2 color types in later generations and in intercrosses.
There remain to be discassed some bits of evidence which, while less direct,
are perhaps no less trustworthy. This evidence deals with (1) the relation
of aleurone color to plant-color types, (2) the linkage of certain plant-color
types with endosperm color, and (3) the Hnkage of other color types
with the liguleless leaf.

Relation of aleurone color to plant color. — Of the plant-color factors
considered in this section of the paper, the pair A a is concerned also
in the development of alem'one color. It has been shown by the writer

Plant Colors in Maize , 59

ill a previous paper (Emerson, 1918) that the presence of three dominant
factorS; A, C, and R, is necessary for the development of aleurone color.
It is assumed that the factor pair A.a for aleurone color is identical with the
pair A a for plant color. Some of the evidence on which this assumption
is based may well be considered at this point in order to justify the
use of the same symbols for both plant and aleurone color. After the
identity oi Aa has been estal)lished, certain relations of aleurone color
to plant color can be used to check up some of the conclusions previously
drawn with respect to the genetic interrelations of the several plant-color
types.

It will be recalled that dilute sun red crossed with green gave dilute
sun red in Fi and a 3:1 ratio of the two types in F2 (table 17, group 1,
page 134), and that backcrosses of Fi with green gave a 1 : 1 ratio (group 2).
The F2 seeds of these Fi plants also exhibited a 3: 1 relation — 424 colored
and 127 colorless, deviation 10.8 ± 6.9 — thus showing that only one
factor pair, A a, C c, or R r, was heterozygous. The colorless seeds
produced 98 green plants, and the colored ones produced 269 dilute sun
reds and 1 weak plant, recorded as green, which died in the seedling
stage. Obviously the factor that differentiates dilute sun red from green
is the same as the one that in these cases differentiated the colored from
the colorless seeds, or some factor very closely linked with it. Fortunately,
Fi plants closely related to the ones which when selfed showed the behavior
noted above, were backcrossed with green, colorless-seeded A testers
(Emerson, 1918). Of the resulting seeds 632 were colored and 590 were
colorless, evidently a 1:1 relation — the deviation being 21 ± 11.8 —
showing that the Fi plants were, with respect to aleurone color, A a
C C R R. The colored seeds gave rise to 357 dilute sun red plants and
the colorless seeds to 358 green plants. Evidently, therefore, it is the
Aa pair that differentiates dilute sun red from green. This is in support
of the assumed genotypes A h pi and a b pi for dilute sun red and green,
x^spectivel}'.

The single progeny recorded in group 3 of table 9 (page 127) came
from a plant known to be A a with respect to aleurone color and pro-
ducing 130 colored and 41 colorless seeds. The 3:1 aleurone-color relation
shows it to have been heterozygous in only one aleurone-color factor,
and therefore AaCCRR. The colored seeds, ACR, produced 67
purple plants, and the colorless ones, aC R, produced 21 brown plants.

60 R. A. Emerson

Evidently, purples are differentiated from browns by the A a pair alone,
just as dilute sun reds are differentiated from greens. This is quite
in keeping with the assmned genotypes, A B PI and a B PI, for purple
and brown, respectively.

Two of the progenies recorded in group 3 of table 8 (page 126) involved
both aleurone and plant color. The heterozygous parents were back-
crossed with green A testers and produced 125 colored and 127 colorless
seeds. The factor pair differentiating these two seed classes was therefore
Aa. The colored seeds, A C R, produced 15 purple and 14 sun red plants,
while the colorless seeds, aC R, gave 9 brown and 14 green plants. Since
it is shown in the preceding paragraph that purples and browns differ
with respect to the pair A a alone, it may be inferred that the sun reds
and the greens of these lots also differed with respect to A a alone. The
assumption heretofore made with respect to the genotypes of these color
classes, A B PI, A B pi, a B PI, and a B pi, for pm"ple, sun red, brown,
and green, respectively, is given support by this relation of aleurone
color to plant color.

Two of the progenies recorded in group 1 of table 9 (page 127), and one
in group 4 of table 8 (page 126), were grown from self-polhnated plants
known to be A a with respect to aleurone color and found to have 644
colored and 228 colorless seeds. The 3 : 1 seed-color relation shows them
to have been AaC C RR. The colored seeds, A C R, gave 294 purples
and 113 dilute purples, while the colorless seeds, aC R, gave 119 browns
and 40 greens. If purples and brov/ns differ with respect to A a alone,
as they have been shown to do, presumably the dilute purples and the
greens of these lots also differ in the same way. This is in keeping with
the assumption that the genotypes of the color classes are A B PI, A b PI,
a B PI, and a bPl, for purple, dilute purple, brown, and green, respectively.

These comparisons of the relations of aleurone color to plant color have
confirmed definitely the supposition that purples, sun reds, dilute purples,
and dilute sun reds have the dominant factor A, and browns and greens
the recessive factor a. The comparisons have also afforded some support
for the assumed genetic constitution of the several color types with regard
to B b and PI pi. More definite evidence for" the latter, however, is
afforded by the linkage relations now to be discussed.

Liyikage of plant color with endosperm color. — It has been known since
1942 that a Unkage exists between the factor pau* PI pi and endosperm

Plant Colors in Maize 61

color. The data siigsost irregularities or complexities which cannot be
straightened out until more definite information is at hand with regard
to the two or more factor pairs concerned in the development of yellow
endosperm.^ Only such data are presented here as are necessary to
show the relations of the several plant-color types to endosperm color,
f A single progeny recorded in table 27, group 2 (page 140), was made
up of 74 purple and 75 sun red plants. The lot resulted from a cross
of a white-seeded sun red plant with a dilute purple plant which was
heteroz3'-gous with respect to both yellow endosperm and plant color. The
j^ellow seeds produced 58 purple and 20 sun red plants, and the white
seeds produced 16 purple and 55 sun red plants. The yellow-seeded
sun reds and the white-seeded dilute purples are known to be the crossover
classes. The ratio of non-crossovers to crossoveis is 113:36, and the
percentage of crossing-over, therefore, is 24.2. Evidently a factor pair for
yellow endosperm, Y y, is linked with the factor pair that differentiates
purple from sun red. In accordance with the hypothesis under test, this
plant-color factor pair is PI pi — purple = ABPl, and sun red = ABpl.
Two other progenies (table 26, group 1, page 139) had a total of 116
dilute purple and 42 dilute sun red plants. The selfed parent plants
were heterozj^gous for yellow endosperm as well as for plant color. The
yellow seeds gave 99 dilute purple and 17 dilute sun red plants, and the
white seeds gave 17 dilute purple and 25 dilute sun rod plants. This
F2 distribution, as shown below, is very close to expectation ( z^ = 0.26)
on the basis of 25 per cent of crossing-ovei between the factor pair Yy
and the pair that differentiates dilute purple from dilute sun red. It seems
likel}^ therefore, that the same plant-color factors, PI pi, are concerned
here as in the progeny consisting of purples and sun reds. This is in
keeping with the theoretical genotypes, A b PI and A b pi. assmned for
dilute purple and dilute sun red, respectively. The comparison between
the observed Fo distribution and that calculated on the basis of 25 per
cent of crossing-over follows:

Observed 99 17 17 25 = 158

Calculated, y 102 17 17 23 = 159

Difference —3 0 0 +2 —1

' This problem is being investigated by Dr. E. G. Anderson.

62 R. A. Emerson

A single progeny (table 8, group 3, page 126) from a selfed parent
heterozygous for yellow endosperm, contained purple, sun red, brown,
and green plants, totaling 63, in the relation 35:15:6:7. These four
color types are expected to occur in a total of 64 in the relation 36: 12: 12:4
from a selfed plant of the genotype AaB B Plpl. The observed deviation
from expectation might occur by chance once in nine trials, P equaling
0.11. Theoretically, the green plants of this lot, aB pi, are differentiated
from the browns, a B PI, by the same factor pair, Plpl, that differentiates
the sun reds, A B pi, from the purples, A B PI. If this is true, the
same linkage relations should exist for yellow endosperm with the
brown-green lot as with the purple-sun-red lot. From yellow seeds there
came 29 purples and 8 sun reds, and from white seeds 6 purples and 7
sun reds. Such a distribution should be very closely realized ( /.^ = 0.97)
from 30 per cent crossing-over between Y y and PI pl. The yellow seeds
produced also 5 brown and 3 green plants, and the white seeds 1 brown
and 4 green plants. While the number of individuals is too small to give
a reliable indication, it is of interest to note that the coefficient of asso-
ciation (Collins, 1912) calculated from the series 5:3:1:4, or 0.739, is
practically that calculated from 26 per cent of crossing-over. In so fai"
as these records go, therefore, they support the assumption that brown
and green in this lot are differentiated by the same factor pair as are
purple and sun red, and thereby support the hypothesis under test.

A plant heterozygous for the three plant-color pairs A a, B b, PI pl,
and for Yy, backcrossed with a white-seeded green plant of type Vic,
a h pl y, gave the six color types, purple, sun red, dilute purple, dilute
sun red, brown, and green, in the numerical relation 10:13:17:11:9:33
(ta])le 6, page 124), which is a close fit (P = 0.61) to the expected relation,
1:1:1:1:1:3. From yellow seeds the resulting series was 8:6:13:2:7 :.17,
and from white seeds it was 2:7:4:9:2:16. When the classes having
A Pl, purple and dilute purple, were lumped together, and similarly
those having A pl, sun red and dilute sun red, the yellow seeds gave 21
plants wifh Pl and 8 with pl, while the white seeds gave 6 with Pl and
16 with pl. Of these 51 plants, there were 14 in the crossover classes,
or a percentage of crossing-over of about 27.5 ±4.1, approximately the
same as in the cases cited above. In this lot there are theoretically three
kinds of greens, a B pl, ah Pl, and a h pl, one of which has Pl and two
of which have pl, while all the browns, a B Pl, have Pl. If there be

Plant Colors in Maize 63

assumed 25 per cent of crossing-over between Fy and PI pi, equivalent

to a 3:1:1:3 gametic series, yellow seeds should give 3 brown to 5 green,
and white seeds 1 brown to 7 green, as shown below:

Yellow White

Brown, a B PI 3 1

Green, a B pi 1 3

Green, ab PI 3 1

Green, abpl 1 3

The yellow seeds actually gave 7 brown to 17 green and the white seeds
2 brown to 16 green, which is a close fit to the calculated relation, 3:5:
1:7 (P = 0.59). In this case as in the others, then, the linkage relations
between Y y and PI pl afford additional support for the belief that the
several color types actually bear to one another the relation assumed in
the assignment of hypothetical genetic formulae (page 32).

Linkage of plant color icith leaf type. — It has been known for some
years that a leaf type termed liguleless (Emerson, 1912) is linked with
the factor pair that differentiates sun red from dilute sun red. As an
illustration of this, two backcross progenies, 8250 and 8253, with a total
of 145 sun red and 147 dilute sun red plants, may be cited. These progenies
came from a cross of normal-leaved sun red, A B pl Lg, with liguleless-
leaved dilute sun red, A b pl lg, backcrossed with liguleless dilute sun red.
Of the normal-leaved plants 104 were sun red and 41 were dilute sun red,
while of the liguleless-leaved plants 48 were sun red and 99 were dilute
sun red. The non-crossovers were to the crossovers as 203:89, or a per-
centage of crossing-over of 30.5. Since the factor pair that differentiates
sun red from dilute sun red has been assigned the symbol B b, the linkage
noted here is evidently between B b and Lg lg.

Six progenies from backcrosses of heterozygous normal-leaved purples
with liguleless dilute sun reds gave purples, sun reds, dilute purples, and
dilute sun reds in the relation 197:177:178:167, which is not far from the
equality expected, P equaling 0.46. Among the normal-leaved plants,
the four color types occurred in the relation 123:117:47:55, and among
the liguleless-leaved plants in the relation 74:60: 131: 112. Evidently the
purples bear the same relation to the dilute purples as the sun reds do to
3

64 R. A. Emerson

the dilute sun reds. For sun reds and dilute sun reds, the non-crossovers
are to the crossovers as 229:115, or a crossover percentage of 33.4 ± 1.7.
For purples and dilute purples, the relation is 254:121, or a crossover
percentage of 32.3 ± 1.5. It follows from this that the factor pair, B h,
which differentiates sun red, A B -pi, from dilute sun red, A b pi, is the
same as that which differentiates purple from dilute purple. And this
is in keeping with the hypothesis under test, in accordance with which
purple and dilute purple have been assigned the genotypes A B PI and
A b PI, respectively.

In a single progeny resulting from a backcross of a heterozygous normal-
leaved purple plant with a liguleless-leaved green plant, greens occurred,
as expected, with about three times the frequency of the average of
the other five color classes. The progeny included 14 browns and 49
greens. Of the normal-leaved plants there were 10 browns and 19 greens,
and of the liguleless-leaved plants 4 browns and 30 greens. On the basis
of the hypothetical genotypes assigned to browns and greens, and with
the assumption of 33 per cent of crossing-over between B b and Lg Ig,
the four classes, normal brown, normal green, liguleless brown, and
hguleless green, should bear the relation 2:4:1:5. For a total of 63
plants, the relation would be approximately 11:21:5:26, whereas the
observed relation was 10:19:4:30. The deviations from expectation are
such as might occur by chance in more than three out of four trials, P
equaling 0.78. In this case, as in the others reported, the linkage relations
between B b and Lg lg afford support for the view that the several color
types bear the relation to one another inferred from the hypothetical
genotypes assigned them.

Summary of results involving A a, Bb, PI pi

The results of the cross of purple with green — which gave in F2 six
color types, namely, purple, sun red, dilute purple, dilute sun red, brown,
and green, with a numerical relation of approximately 27:9:9:3:9:7
from selfed Fi's and about 1:1:1:1:1:3 from Fi's backcrossed to green —
have been interpreted on the basis of the interaction of three factor pairs,
A a, Bb, and PI pl. This hypothesis has been subjected to practically
every genetic test available, as summarized below.

Each of the six Fo color types has in turn been tested by its behavior
in F3, and in several cases behavior in F4 and even in later 'generations

Plant Colors in Maize 65

has been noted. All the possible combinations of intercrosses between
the several types have been studied, except dilute purple x brown. In
most cases these intercrosses have been carried to the F2 generation,
and in several instances to F3 and F4. Thruout the tests, the results
have been in close agreement with those expected from the hypothesis.
In almost every instance all the color types expected in each generation
of the several crosses, and no others, have appeared. Moreover, the
numerical relations found to exist between the several color types and also
between the several classes of behavior have been reasonably close to
expectation. It is true that in some instances the fit of observation
to hypothesis has not been particularly good, but even here the observed
deviations have been of such an order as might be expected to occur
occasionall}^ thru the chance errors of random sampling.

In addition to the tests afforded by the behavior of the several Fj
color types in later generations and in intercrosses, the relations of aleurone
color involving the factor pair A a to tlie several plant colors, and the
linkage relations of the plant-color factors PI pi with the endosperm-color
factors Y ij and of the plant-color factors B h with the leaf-type factors
Lg Ig, have been included in the investigation. These tests have shown
that the several color types bear to one another the relations to be deduced
from the hypothetical genotypes assigned them.

The conclusion seems justified, therefore, that the three-factor hypoth-
esis proposed as an interpretation of the F2 results obtained in crosses
of purple with green has been substantiated, in so far as it is possible
to substantiate any hypothesis.

CROSSES INVOLVING THE MULTIPLE ALLELOMORPHS B, B'^ , b\ b

In the preceding section of this account, six color phenot3'pes of maize
have been discussed, namely, purple, sun red, dilute purple, dilute sun
red, brown, and green. In addition to these six phenotypes, green plants
have been shown to consist of three genotypes, which in some instances
are slightly different phenotypically. Besides these six sharply separable
phenotypes, there exist certain intermediate forms. The constancy
of the.se types from year to year, under fairly uniform environmental
conditions, leaves no doubt that they are genotypically as well as pheno-
typically distinct from the types considered heretofore.

66 R A. Emerson

One of these forms, known as weak purple, type lb, is intermediate
in certain respects between purple and sun red, and in other respects
between purple and dilute purple. Plants of this type, prior to the
flowering stage, frequently resemble sun reds more than purples. The
pigmentation of the sheaths is less intense than with purples, and in
some instances less than with strong sun reds. There is, however, sooner
or later a tendency for pigment to develop on the stalk beneath the
sheaths (Plate V, 2) , In this respect weak purples resemble dilute purples
as the latter often appear in a' late stage of their development. The
anthers of weak purples are usually full purple, like those of purples
and dilute purples, in which respect they show no resemblance to sun reds.

A second intermediate form, known as weak sun red, type lib, stands
between sun red and dilute sun red. The sheaths and husks are less
extensively and less intensely pigmented than is true of full sun red, and
yet exhibit much more color than in dilute sun red (Plate V, 4). The
anther color of weak sun red is like that of both sun red and dilute sun
red.

While the difference between the extreme sun-color types, sun red and
dilute sun red, is probably only a quantitative one — as is also presumably
true of the difference between purple and dilute purple — little difficulty
is experienced in separating sun red from dilute sun red plants on the one
hand, or purple from dilute purple plants on the other. Frequently,
however, it is difficult, or even impossible, at early stages of plant growth,
to separate sun reds from purples. The existence of such intermediate
forms as weak purple and weak sun red adds materially to the difficulties
of classification. In fact, correct classification of all these types by inspec-
tion alone is possible only at the flowering stage. For certainty in classi-
fication, even at the flowering stage, environmental conditions, particularly
soil fertility, must have been favorable thruout the growing period of the
plants. While infertile soil exaggerates the difference between dilute
sun red and green, by bringing about an excessive development of red
■ pigment in the one type while no color develops in the other, on fertile soil
only are revealed the finer distinctions between sun red, weak sun red,
and dilute sun red. It is perhaps fortunate that the genetic relations of
these several types are such that ordinarily not all of them occur in a
single progeny.

Plant Colors in Maize 67

Interrelations of sun red Ila, weak sun red lib, and dilute sun red IVa

Numerous crosses of weak sun reds, lib, with dilute sun reds, IVa,
have given weak sun reds in Fi and approximately three weak sun reds
to one dilute sun red in F2, just as crosses of strong sun red with dilute
sun red give three strong to one dilute sun red (table 24, group 1, page 138).
Records of such crosses are given in table 32 (page 144). Twelve F2
progenies, totaling 1729 individuals, showed the two types in the relation
1300:429, almost exactly a 3:1 ratio, the deviation being 3.3 ± 12.1.
The data for F3 of these crosses are like those for crosses of strong sun red
with dilute sun red (table 25). One weak sun red F2 bred true in F3
with a total of 77 weak sun red offspring (table 33, group 1). Four others
gave both weak and dilute sun reds (group 2), in the relation 128:54, a
deviation of 8.5 ± 3.9 from a 3:1 ratio. One dilute sun red bred true
(group 3), with 95 dilute sun red plants in F3.

A cross of weak sun red, lib, with strong sun red, Ila, gave strong sun
red in Fi and the two parent types in F2 in the relation 71 : 16, a deviation
from the 3: 1 ratio of 5.75 ± 2.72. There is, therefore, nearly one chance
in six that the observed deviation may be due to errors of random sampling,
P equaling 0.16.

In none of these crosses, strong with weak, weak with dilute, and strong
with dilute sun red, have other than the parent types appeared in F2.
If weak sun red is due to the action of some additional modifying factor,
not heretofore considered, types other than those of the parents should
have occurred in some of the crosses. The natural conclusion, therefore,
is that weak sun red, lib, is due to an allelomorph of B and b, the pair
concerned with the difference between sun red, I la, and dilute sun red,
IVa. This third allelomorph, responsible for weak sun red, may well be
designated B^.

Further evidence in support of the assumption that an allelomorph of
B and b is concerned with weak sun red is afforded by linkage studies
involving strong, weak, and dilute sun red with loaf type. Evidence has
been offered (page 63) to show that B b and Lg Ig are linked with about
30 to 33 per cent of crossing-over.

A single progeny, 8252, from a sun hkI plant heterozygous for leaf type
and plant color backcro.ssed to liguleless weak sun red, contained 108
sun red and 109 weak sun red plants. Of the normal-leaved plants 80

68 R- A. Emekson

were sun red and 38 were weak sun red, while of the Hguleless-leaved plants
28 were sun red and 71 were weak sun red. The ratio of non-crossovers
to crossovers is 151:66, or 30.4 ± 2.1 per cent of crossing-over. The
percentage of crossing-over between Lg Ig and the factor pair differentiating
sun red and weak sun red, B B"", is, therefore, practically the same as the
linkage between Lg lg and B b.

Four backcross progenies, 8246-8249, involving sun red, contained 469
weak sun red and 396 dilute sun red plants. Of the normal-leaved plants
153 were weak sun red and 261 were dilute sun red, while of the liguleless-
leaved plants 316 were weak sun red and 135 were dilute sun red. The
non-crossovers are to the crossovers as 577:288, or 33.3 ±1.1 per cent of
crossing-over. Here again, therefore, the linkage between Lg lg and the
factor pair differentiating weak sun red from dilute sun red, B^ b, is
practically the same as that between Lg lg and B b or between Lg lg and
BB"".

From the facts (1) that in crosses between any two of the three types
sun red, weak sun red, and dilute sun red, the third type is not produced,
and (2) that the linkage value between Lg lg and the factor pairs differen-
tiating weak sun red from sun red and from dilute sun red is approxi-
mately the same as that between Lg ly and B b, it seems evident that weak
sun red is due to a factor B^ belonging to the triple allelomorphic series
B, 5"', b.

It seems probable that this series of allelomorphs contains other members
in addition to the three listed above, but there is at present little conclu-
sive evidence in support of the idea. There are certainly several forms,
commonly classed as dilute sun red, that differ considerably in the amount
of red pigment developed, and certainly some of these differences are
genetic. As is shown in the next section of this account, some of these
differences, particularly with respect to silk, anther, and leaf-blade color,
are due to the effect of the aleurone-color factors R r. Environmental
conditions, particularly soil fertility, influence the development of this
pigment so greatly that the prol^lem becomes a difficult one. There is,
however, some evidence that at least two forms of dilute sun red are
differentiated by a factor pair belonging to the series B, B^, b. These
forms differ principally in the amount of color in the fresh husks (Plate
VI, 1 and 2), and to some extent in the sheaths, which arc the plant parts
most strikingly different in sun red, weak sun red, and dilute sun red.

Plant Colors in Maize 69

A type of dilute sun red with stronger husk pigmentation than ordinary
dikite sun red shows was crossed with an ordinary dihite purple. Leaf
type also was involved in the cross. The Fi plants were dilute purples
with somewhat more pigment in the husks of young ears than is usual
with that type. A single progeny, grown from an Fi backcrossed with
liguleless dilute sun red of a light type, consisted of 25 dilute purples and
18 dilute sun reds. Each of these classes was sorted with some difficulty
into light and more strongly colored subclasses, in accordance with the
amount of color on the husks of the young ears. Of the more strongly
pigmented dilute sun reds 4 had normal and 6 had liguleless leaves, while of
the lighter dilute sun rods 6 had normal and 2 had liguleless leaves. Of the
more strongly colored dilute purples 4 had normal and 13 had liguleless leaves,
while of the lighter ones 4 had normal and 4 had liguleless leaves. While
these numbers are small and the behavior was somewhat irregular, it is
perhaps noteworthy that the factor pair differentiating the lighter from
the more strongly colored plants, of both the dilute sun red and the dilute
purple classes, exhibited an apparent linkage with Lq Ig of a value not
far from that observed between Lg Ig and B b, B B^, and B^ b. The
observed percentages of crossing-over were 32.0 for the dilute purples,
33.3 for the dilute sun reds, and 32.6 for the entire lot. This evidence,
slight as it is, plainly suggests a fourth member, b% of the B series of
allelomorphs, which may be stated tentatively as B, B^, 6*, b.

Relation of weak purple lb to purple la, dilute purple Ilia, and weak sun

red lib
By methods similar in the main to those outlined above, Dr. E. O.
Anderson has been able to show that weak purple is differentiated from
purple on the one hand and from dilute purple on the other by the same
factor, B^, that differentiates weak sun red from sun rod and from dilute
sun red. At the time when Dr. Anderson undertook to determine the
genetic relations of weak purple, nothing was known of the relation of
weak sun red to sun red and dilute sun rod as presented above. Further-
more, there was no indication as to whether weak purple was dififerentiated
from purple and dilute purple by an allelomorph of /^ 6 or of PI pi, or by
some distinct factor pair that might modify the ordinary result of the
interaction of the pairs A a, B h, and PI pi then known to be concerned
in the production of plant colors. The evidence to be presented here

70 R- A. Emerson

is taken almost wholly from Dr. Anderson's records, and the conclusions
derived from it are his. It is with Dr. Anderson's permission and at
his suggestion that, for the sake of completeness of this account of the
inheritance of plant colors, his results are here presented.

A cross of a weak purple lb with a homozygous dilute purple Ilia
resulted in 25 weak purples only, while a cross of another weak purple
with a homozygous dilute purple, a sib of the plant used in the first cross,
gave 63 weak purples and 53 dilute purples. Two of the Fi weak purples
were backcrossed to dilute purples, and a third to dilute sun red. The
result (table 34, group 1, page 145) was 141 weak purples and 163 dilute
purples, a deviation of 11 ±5.9 from equality.' Five crosses of weak
purples with dilute sun reds gave a total of 32 weak purples and 25 dilute
purples, a deviation from equality of 3.5 ± 2.5, while two other such
crosses gave 29 weak purples only. Evidently these weak purple plants
differed from dilute purples by a single factor pair. This pair could not
have been PI pi, for the crosses of weak purple with dilute purple, A b PI,
gave the same results as those with dilute sun red, Ab pi. This leaves the
■possibility that B b or some unknown factor pair was concerned.

Three crosses of weak purple lb with purple la resulted in 52 purple
plants. A single cross of weak purple with sun red Ila gave 18 purples.
Evidently both purple and sun red carry some factor that acts to change
weak purple fco purple. Unfortunately, no later generations of any of
these crosses were grown, but it is evident from the Fi results and from
what is known of the interrelations of purple, sun red, and dilute purple
that the dominant factor B, common to both purple and sun red, is con-
cerned in the change from weak purple to purple. Since the crosses of
weak purple with dilute purple, A b PI, and with dilute sun red, A b pi,
gave no purples, while crosses of weak purple with purple, A B PI, and
with sun red, A B pi, gave purple, the Pljjl pair is not concerned in the
difference between weak purple and purple any more than in that between
weak purple and dilute purple. These results, however, do not exclude
the possibility that weak purple may be Ab PI, like dilute purple, with
the addition of some unknown dominant modifying factor.

A single weak purple plant, which was, so far as known, imrelated to
the weak purples considered above, when crossed with two unrelated
dilute sun reds gave progenies consisting of 15 weak purples and 13 weak
sun reds. Seven progenies of these Fi weak purple plants backcrossed

Weak

Dilute

Dilute

T'^ + r.l

sun red

purple

sun red

iotai

lib

Ilia

IVa

526

460

537

2,004

501

501

501

2,004

Plant Colors ix Maize 71

with dilute sun reds are listed in table 34, ^mnp 2. These progenies
consisted of four color types, weak purple, weak sun red, dilute purple,
and dilute sun red, in the numerical relations given below:

Color types ^^'^f

''^ purple

lb

Observed 481

Calculated 501

Difference —20 +25 — 4i +36 0

The deviations from equality of the four classes expected of a dihybrid
are so great that they would not occur by chance alone more than once
in twenty trials, P equaling 0.05. Dr. Anderson's notes indicate that
there was considerable difficulty, in the case of two of the cultures, in dis-
tinguishing dilute purple from dilute sun red. Whether this difficulty
may account in part for the poor fit is not known. The outstanding fact,
however, is the appearance of the four classes and no others. Since
weak sun red is known to differ from dilute sun red by the factor pai'
B^' b, the inference is clear that weak purple differs from dilute purple by
Ihe same pair and by no others. The formvdae assumed for the
four color types are, therefore, A B^ PI, A B"' pi, A b PI, and A b pi,
respectively.

If the foregoing conclusion is correct, crosses of weak sun reds with
dilute purples should give weak purples in Fi and the same four color
classes in F2 as are noted above for crosses of weak purple with dilute sun
red. A single cross of a dilute purple with a homozygous weak sun red
resulted in 18 weak purple plants. Two crosses of dilute purples with
weak sun reds heterozygous for B^ b gave 12 weak purples and 11 dilute
purples. That the production of weak purples in these crosses was not
due to the b or PI factors of the dilute purple parents is evidenced by the
fact that crosses of the same dilute purple individuals witli sun reds
gave full purples in Fi. One of the Fi weak purples, A A B'^ b PI pl,
of the above crosses was backcrossed with dilute sun red, A bpl, with the
result (table 34, group 3) showa below. The expected equality of the

Weak

Dilute

Dilute

sun red

purple

sun red

iotai

lib

Ilia

lYa

28

22

27

98

24.5

24.5

24.5

98

72 R. A. Emerson

four color types was closely approached in the results, x^ equalmg 0.80.
The comparison of observed with expected results follows:

! Color tj^es "^^^^^

I '' ^ purple

' lb

Observed 21

Calculated 24 . 5

Difference..- —3.5 +3.5 —2.5 +2.5 0

The progeny of a purple plant heterozygous for B B"^, PI pi, and the
endosperm color pair Y ij, backcrossed with a white-seeded weak sun red
plant, A B^ pi y, affords evidence of another kind with respect to the
interrelations of strong and weak purple and of strong and weak sun red.
It has been noted previously (page 60) that PI pi and Yy are Imked, with
a somewhat irregular percentage of crossing-over. The backcross gave
the four color types purple, weak purple, sun red, and weak sun red, in
the numerical relation 60:48:59:62. The observed deviations from the
equahty expected of a dihybrid are such as might occur by chance more
than once in two trials, P equaling 0.54. The distribution of these 229
plants to the four color types when the progeny of yellow seeds and that
of white seeds are considered separately is as follows:

Color types

Purple

vv eaK

purple

Sun red

la

lb

Ila

Yellow seeds

48

36
12

8

White seeds

12

51

Total

Weak

sun red

lib

17 109

45 120

Evidently weak purple, assumed to be A B"" Pi, here bears the same
relation to weak sun red, A B"' pi, that purple, A B Pi, ]& known to bear
to sun red, A B pi. In case of the purples and the sun reds alone, the
linkage of PI pi with Y y is, shown by 99 non-crossovers to 20 crossovers,
or 16.8 ± 2.7 per cent of crossing-over. When the weak purples and
the weak sun reds are alone considered, the non-crossovers are to the
crossovers as 81:29, a crossover percentage of 26.4 i 2.8. While the

Weak

sun red

lib

Dilute

purple

Ilia

Dilute
sun red
IVa

Total

315
125

119

280

164
317

894
830

Plant Colors in Maize 73

difference between these two percentages of crossing-over, 9.G ± 3.9, is
consiclera])le, it is probably not statistically significant, P equaling 0.09.
Still further evidence in favor of the assumption that weak purple is
differentiated from dilute purple by the factor pair /i"' b, just as weak
sun red is differentiated from dilute sun red, is afforded by data from six
of the progenies recorded in group 2 of table 34. These data, it will be
recalled, were obtained from Fi's of weak purple x dilute sun rod back-
crossed to dilute sun red. The Fi weak purples were heterozygous for
liguleless leaf as well as for plant color, AAB^bPlplLglg, and the dilute
sun reds with which they were backcrossed were liguleless, A b yl Ig. The
1724 plants were distributed as follows:

Color types ^\"^^^^

lb

Normal leaves 296

Liguleless leaves 108

Evidently the linkage relations of liguleless with weak purple and dilute
purple are similar to those already known for liguleless with weak sun red
and dilute sun red (page 67). Of the 921 weak svm reds, A B^ pi, and
dilute sun reds, A b pi, 632 belong to the non-crossover and 289 to the
crossover class, a percentage of crossing-over of 31.4 rb 1.0. Similarly,
of the 803 weak purples and dilute purples, the non-crossovers are to
the crossovers as 576:227, a percentage of crossing-over of 28.3 ± 1.1.
The difference between these two percentages of crossing-over, 3.1 rb 1.5,
is such as might occur by chance once in six trials, P equaling 0.16.

By way of summary, it may be noted that, from appropriate intercrosses
of the several color typos and from determinations of the linkage relations,
of these types with liguleless leaf and with yellow endosperm, weak purple
and weak sun red have been shown to have the genotypes A W" PI and
A B^ pi, respectively. This establishes the existence of the triple alle-
lomorphs, B, B'" , b. There is some evidence in favor of the occurrence
of a fourth member of this series, b".

CROSSES INVOLVING THE MULTIPLE ALLELOMORPHS /?'', Hf, W^ , /, 1^ , r*^

In an earlier section of this account (page 29) dealing with crosses involv-
ing only A a, B b, and PI pi, three types of green plants were reported,

74 R. A. Emerson

namely, a B pi (Via), ah PI (VIb), abpl (Vic). Still another type of
green — a type wholly devoid of purple, red, or brown pigment — has been
used in several crosses, with results quite unlike those obtained from corre-
sponding crosses with the other green types. For reasons that })ecome
apparent later, this fourth type of green is regarded as genetically similar
to dilute sun red and is known as type IVg.

Green IVg x brown V

Generations F\ and F^. — When brown, a B PI, is crossed with green
of any of the three types previously studied, brown appears in Fi and
brown and green in F2. If green VTc, a b pi, is used in the cross, the F2
ratio approaches 9 : 7, while if green Via, a B pi, or VIb, a b PI, is used,
3:1 F2 ratios are of course expected (tables 19 and 20, page 135). In
striking contrast with such results are those obtained from a cross of
brown with green IVg. Two such crosses gave 78 purple plants in Fi,
and a third cross resulted in 72 purple and 63 sun red plants. It will be '
recalled that just such results as these were obtained from crosses of dilute
sun red with brown (tables 4 and 14, pages 123 and 131). The brown plant,
2031-20, which gave purple and sun red Fi plants when crossed with green
IVg, was the identical plant previously reported (table 4, group 2) to have
given 55 purples and 55 sun reds when crossed with a dilute sun red plant.
Moreover, this same brown plant was shown (table 20, group 2, page 135)
to have produced from self-pollination 82 browns and 34 greens. Evi-
dently it was aa B B PI pl. The important point here is that crosses
of brown with green IVg give exactly the same results in Fi as if green
IVg were a dilute sun red, A A bb pl pl.

There are other reasons, in addition to the Fi results of crosses with
brown, for supposing that green IVg has the factor A. When the pericarp-
color gene P occurs together with A, the resulting pericarp color is always
red, but when P and a a are associated the pericarp color is brown. When
green IVg plants have pericarp color it is red rather than brown, while
that of greens Via, VIb, and Vic is always brown. Again, the A factor
is known to be essential to the production of aleurone color (Emerson,
1918), and the stock of IVg green plants used in these crosses, a strain
of the variety Black Mexican sweet corn, was homozygous for purple
aleurone. It is noteworthy in this connection that many, perhaps most,
plants of this variety show very slight traces of sun red, and these traces are

Plant Colors in Maize 75

limited commonly to the glumes of the staminatc inflorescence. Appar-
ently the stock of green IVg, which under no environmental conditions
to which it has been subjected has ever been observed to produce the
slightest trace of sun red, is merely an extreme minus variation of dilute
sun red.

Not only were the Fi results of the cross of brown with green IVg like
those of the cross of brown with dilute sun red, but the same major color
types appeared in F2 (table 35, page 145). The distribution of all the indi-
viduals of six F2 progenies to the six major color types heretofore recognized
is compared below with the theoretical distribution calculated on the
assumption that the green IVg parent was genotj^pically a dilute sun red,
A Ahb pi pi:

Color types Purple Sun red ^jj.^*^ ^"^"^^^^ Brown Green Total

Observed 309 100 67 19 88 98 681

Calculated 287 96 96 32 96 74 681

Difference +22 +4 —29 —13 —8 +24 0

The outstanding features of this comparison are the relatively small
deviations, in comparison with the number of individuals, for the purple,
sun red, and brown types, and the relatively large deviations for the dilute
purple, dilute sun red, and green classes. The relative importance of
the several deviations is best seen by a comparison of the quotients of
calculated frequencies into the squares of corresponding deviations, from
which z2 and P are derived (Elderton's and Pearson's tables). These
quotients for the several classes are:

T^ 1 a J Dilute Dihite t> n

Purple Sun red 1 ■, Brown Green

^ purple sun red

1.69 0.17 8.76 5.28 0.67 7.78

If these quotients were no greater in the case of dilute purple, dilute
sun red, and green than for purple, sun red, and brown, there would be
about two chances in five that the observed deviations might be due merely
to errors of random sampling, a fairly good fit being shown — /^ = 5.06,
P = 0.41. But as they stand, these deviations could be expected to occur
thru chance alone not more than once in five thousand similar trials, a

76 'R. A. Emerson

very poor fit being shown — z^ = 24.35, P = 0.0002. Evidently, green
IVg does not give the same results in F2 of this cross as does dilute sun

red.

It is to be supposed, of course, that green IVg differs in some essential
genetic way from dilute sun red, else it would not remain true green for
generation after generation while the typical dilute sun red constantly
produces a conspicuous amount of sun red pigment. It was therefore to
be expected that the dilute sun red class would be deficient in F2 while
the green class would show a corresponding excess. But if the 24 green
plants in excess of the calculated number be added to the dilute sun red
class, that class becomes too large by eleven individuals, the excess now
becoming almost as great as the observed deficiency. Moreover, the dilute
purple class, it must be remembered, remains greatly deficient. If it be
supposed that the excess of greens came about at the expense of dilute
purples as well as of dilute sun reds, a very good fit of observation to theory
is obtained'. On redistribution of the 24 greens in excess of expectation
to the dilute purples and dilute sun reds in the 3 : 1 relation usually existing
between these classes, the corrected distribution for the six classes is as
shown below. There are almost two chances in five that the deviations
may be due to random sampling, P equaling 0.38.

Color types Purple Sun red ^"^"^^^^ g^'^''^!^^^ Brown Green Total

Corrected distribu-
tion 309 100 85 25 88 74 681

Calculated 287 96 96 32 96 74 681

Difference +22 +4 —11—7—8 0 0

Mere closeness of fit cannot, of course, be regarded as proof of the
supposition on which the corrected distribution was made. But there are
other considerations which greatly strengthen the hypothesis. In the
case of all the F2 progenies listed in table 35, it was o]:)served that some of
the purple plants, altho quite as strongly colored otherwise as normal
purples, had wholly green anthers in place of the usual dark purple ones
(Plate I, 4). Likewise some of the sun red plants had green instead of
pink anthers. In striking contrast to this, not a single dilute purple or
dilute sun red plant with green anthers was seen hi the whole lot, the dilute

Plant Colors in Maize 77

purples, so far as observed, having dark purple anthers and the dikite
sun reds pink anthers, just as in the lots considered in the first section of
this paper. Counts of the purple and the sun red plants with different
anther colors were made for only three of the six F2 progenies (table 36),
and for these lots not every plant was noted at the time when it was possible
to determine the anther color positively. When some anthers have become
dry and weathered, it is impossible to tell whether they were pink or green
when fresh. Less difficulty is experienced with purple anthers, which
hold their color much longer. Unfortunately, the records of the three
F2 families were not made early enough for positive identification of anther
color of all plants. Of 1G2 purple plants, 117 had purple anthers and 33
had green anthers, while 12 were not recorded. Of 50 sun red plants, 21
had pink anthers and 12 had green anthers, with 17 not recorded. In
these two lots the plants with purple and pink anthers were together
about three times as numerous as those with green anthers, thus suggest-
ing a simple monohybrid relation between colored and green anthers.

Working hypothesis. — If the genetic factor which is responsible for green
anthers of purple and sun red plants be assumed to cause, in the case of
dilute purples and dilute sun reds, not merely the anthers but the whole
plant — leaves, sheaths, husks, glumes, stalk, and so forth — to be green,
a satisfactoiy working hypothesis is afforded. The factor concerned here
has been found to be the well-known aleurone-color factor R, or else some
factor very closely linked with it. Some of the evidence on which this
statement is based is presented later in this paper (pages 80, 98). It may be
pointed out in passing that the relation between anther color and aleurone
color here noted was studied by Webber (1906) some years before the
several aleurone-color and plant-color factors had been determined.

Since aleurone color is not primarily concerned in the present account,
it might be less confusing if the case were regarded as one of complete
hnkage, and if some other symbol for anther color were used and all
reference to the R factor omitted in this paper. Until recently there
was nothing known of aleurone-color })ehavior that made necessary the
assumption of more than the simple factor pair, R r. The plant-color
behavior, on the other hand, as becomes apparent later, necessitates the
assumption of a group of multiple allelomorphs responsible in turn for
diverse combinations of colors of leaves, sheaths, anthers, silks, and other
plant parts. The commonest combinations in the writer's cultures are

78 R. A. Emerson

strong pink anthers with deep red silks, hghter pink anthers with red-
dish or pinkish silks, green anthers with green silks, and so on, but there
exist also such combinations as strong pink anthers with green silks,
green anthers with reddish silks, and the like. Moreover, different inten-
sities of dilute sun red in leaf blades, glumes, and other parts are sometimes
combined with various silk-color and anther-color combinations. There
is evidence that at least several of these combinations behave as would be
expected if each were a definite unit allelomorphic to any one of the others.

Perhaps the most remarkable feature of this series of allelomorphs —
or supposed allelomorphs — is the fact that a single unit behaves as a
dominant with respect to the color of one plant part and as a recessive
with respect to that of another part. Thus, a combination of dominant
pink anthers with recessive green siUvS is common in the writer's cultures.
The wholly green plants used in the crosses here under consideration are
recessive for green silks, anthers, glumes, sheaths, husks, and other parts,
and dominant for colored aleurone. Since the aleurone-color symbols
R r have long been employed in the usual way, R as the dominant and
r as the recessive allelomorph, this usage is adhered to in this paper. The
effect of these factors on plant color is indicated by superscripts. Thus,
both R^ and / are dominant allelomorphs with respect to pink anthers
and reddish silks, while both R^ and r^ are recessive for green anthers,
silks, and so on. In the crosses here considered it is known that / and
R^ are the pair concerned. With respect to plant color, therefore, as
contrasted with aleurone color, / is dominant and R^ is recessive. While
it is realized that this usage may tend to confuse the hasty reader, the use
of any other symbols that have so far suggested themselves would result
in greater confusion ultimately, particularly when the interrelations of
plant color and aleurone color are taken up.

To return to the F2 behavior of crosses of green IVg with brown, the
following notation should express the F2 results obtained, provided the
proposed hypothesis is tenable:

Phenotypes

Plant color

Anther col

81-

-ABPlr"-— la

Purple

Purple

27-

-ABPIR"— Ig

Purple

Green

27-

-AB'plr'- — Ila

Sun red

Pink

9-

~ABplR"~ Ilg

Sun red

Green

27-

-Ab PI r'— Ilia

Dilute purple

Purple

Plant Colors in Maize 79

Phenotypes Plant color Anther color

Q—AhPlR"— Illg Green Chven

9 — Ah pi r'' ■ — / Va Dilute sun red Pink

S — AbpIR" —I Vg Green Green

27 — a B PI r'-— V Brown Green

Q — aBPIR"— V Brown Green

9 — aBplr'' — Via Green Green

3 — aBplR" — Via Green Green

9 — abPlr'- ^Vlb Green Green

Z — abPlR" —VIb Green Green

3 — abj)l r'' — Vic Green Green

1 — abplR" — Vic Green Green

256

The theoretical numerical relation between the several color combi-
nations, in the order given above except that all greens are included in the
last class, is 81:27:27:9:27:9:36:40, total 256.

The distribution of the 353 individuals of the three F2 progenies for
which anther records were made (table 36, page 146) is compared below
with the theoretical distribution. In order that all plants may be included,
the few purple and sun red plants whose anther colors were not noted
are arl^itrarily distributed to the colored-anther and green-anther classes
in a 3 : 1 ratio. The fit of observation to hypothesis is so good that there
are three chances in five that the deviations may be due to errors of random
sampling, P equaling 0.60.

Plant color Purple Purple Sun red Sun red ^^[."^^j^ ^^^^^^ Brown Green Total

Anther color Purple Green Pink Green Purple Pink Green Green

la Ig Ila Ilg Ilia Wa V Illg, IVg, VI

Observed 126 36 M 16 39 10 42 50 353

Calculated 112 37 37 12 37 12 50 55 352

Difference -\-U —1 —3 +4 -^2 —2 —8 —5 -|-1

TMien the six Fo progenies listed in table 35, for three of which no records
of anther color were made, are grouped without reference to anther color,
the comparison of observed and calculated numbers are as given below.
For the six progenies there is practically an even chance that the devia-
tions ma}^ be due to errors of random sampling, P equaling 0.48. It will
be recalled that when these same progenies were compared with the dis-

Purple

Sun red

Dilute
purple

Dilute
sun red

BrowTi

Green

Total

la

Ila

Ilia

IVa

V

Illg, IVg, VI

309

100

67

19

88

98

681

287

96

72

24

96

106

681

80 R. A. Emerson

tribution calculated on the basis of the three-factor hypothesis, the fit
was very poor, P equaling 0.0002 (page 76). Comparison of the observed
distribution with the distribution calculated on the four-factor basis follows :

Color types

Observed

Calculated

Difference -^22 +4 —5 —5 —8 —8 0

Relation of aleurone color to plant color. — It is evident from the compari-
sons already given that the four-factor hypothesis fits well the F2 data,
which is of course to be expected since it was invented for that purpose.
But this fact alone is far from a substantiation of the hypothesis. The
genetic tests ordinarily available are the behavior of the several F2 types
in later generations and in intercrosses. Since aleurone color as well as
plant color is involved in these crosses, still another test can be employed.
The six Fi plants whose Fo -progenies are recorded in table 35 produced
from self-pollination a total of 955 seeds, of which 388 had colored and 567
colorless aleurone. This obviously approaches closely a 27:37 ratio, the
percentage of colorless seeds being 59.4 ±1.1 while the theoretical per-
centage is 57.8 (Emerson, 1918). The deviation from expectation,
1.6 ± 1.1 per cent, is such as might be expected by chance once in three
trials, P equaling 0.33. Evidently, therefore, the aleurone factors A, C,
and R are concerned in these crosses. Since A and R are assumed by the
hypothesis to be plant-color factors also, there is afforded opportunity of
comparing the plant-color classes fi'om colored with those from color-
less seeds. Since colored aleurone requires the interaction oi A, C, and R,
colored seeds should never produce brown j^lants nor green plants of type
VI, both of which are a a. As seen from the data given below, no brown
plants came from colored seeds but a few wholly green plants appeared.
Greens of type IVg are of course to be expected from seeds homozygous
for R^. Owing to the fact that a larger percentage of colorless than of
colored seeds produced plants, the theoretical distribution with respect
to plant color, given below, was calculated separately for colored and for
colorless seeds. J^or the colored seeds there are nearly two chances in

Plant Colors in Maizk 81

five (P equaling 0.58), and for the colorless seeds only about one chance in
fovn-teen (P equaling 0.07), that the observed deviations may be due to
errors of random sampling. The comparisons follow:

Color types Purple Sun red ^^'[.'J^J*^ ^^''^^^^ Brown Green Total

la Ila Ilia R'a V Illg, IVg, VI
Colored seeds:

Observed 14S .51 25 8 0 23 255

Calculated 143 48 32 11 0 21 255

Difference +5 +3 —7 —3 0 +2 0

Colorless seeds:

Observed 161 49 42 11 88 75 420

Calculated 136 45 39 13 104 89 426

Difference +25 +4 +3 —2 —16 —14 0

It is noteworth}^ that the ratio of purples and sun reds to dilute purples
and dilute sun reds is considerably greater for plants grown from colored
seeds than for those from colorless seeds. This is to be expected from
the fact that R must be present in all colored seeds, while some of the
colorless seeds here concerned were doubtless r r. Hence, R^ R^ should
have occurred more frequently in the colored than in the colorless seeds,
and should, by the hypothesis here under test, have reduced the numbers
of dilute purples and dilute sun reds, causing these plants to appear as
greens, types Illg and IVg. If the 23 green plants grown from colored
seeds are added to the dilute purples and dilute sun reds, the ratio of
strong to dilute purples and sun reds approaches closely the ratio observed
for the plants from colorless seeds.

It is even more instructive to note the relation of aleurone color to plant
color in the case of the three F2 lots for which anther colors were recorded
(table 36, page 146). For this comparison the few purple and sun red
plants whose anther colors were not recorded have been distributed to
the colored-anther and green-anther classes in approximately the ratio
in which these anther colors were found to occur in the cases in which anther
colors were recorded. Since a larger proportion of colorless than of colored
seeds produced plants, the theoretical (list rilnit ion has i)cen calculated
separately for the two classes of seeds. The comparisons follow:

82 * R. A. Emerson

Plant color Purple Purple Sun red Sun red ^pjg guli red ^^^"^ ^'"^^^ ^^^^^

Anther color Purple Green Pink Green Purple Pink Green Green

la Ig Ila Ilg Ilia IVa V Illg, IVg, VI
Colored aleurone:

Observed 48 25 11 12 16 4 0 10 126

Calculated 47 24 16 8 16 5 0 10 126

Difference +1 +1—5+4 0—10 0 0

Colorless aleurone:

Observed 78 11 23 4 23 6 42 40 227

Calculated 62 10 21 4 21 7 55 47 227

Difference +16 +1 +2 0 +2 —1 —13 —7 0

In view of the rather large number of plant-color classes and the com-
paratively small number of individuals concerned here, the fit of the
observed to the theoretical distribution is remarkably good. The devia-
tions are such as might be expected by chance seven times in ten trials
for the colored-seeded lot (P = 0.70), and about once in four trials for the
colorless-seeded lot (P = 0.26). In addition to this comparison of the
lot as a whole, it should be noted that, while among the purple and sun red
plants as a whole the expected relation of colored (purple and pink)
anthers to colorless (green) anthers i.s 3:1, for the colored-seeded lot it
is 2:1 and for the colorless-seeded lot it is 6:1. The observed relations
were 59:37 and 101:15, or about 1.6:1 and 6.7:1, respectively. On the
whole, therefore, this comparison, involving aleurone color as well as plant
color, supports the suggested factorial interpretation.

Later behavior of F2 purple I. — Only three F2 purples with purple anthers
were tested in F3. One of these, 2960-9, resulted in purple plants with
purple, la, and green, Ig, anthers, and sun red plants with pink, Ila, and
green, Ilg, anthers, in the respective numbers 14:9:6:3. A purple plant
of the genotype A A B B PlplB!' / should give these four classes in
the relation 18:6:6:2, The observed deviations might be expected twice
in five trials, P equaling 0.41.

Another F2 purple plant, 2958-8, gave F3 progeny consisting of the same
eight color types as were seen in F2 in table 36 (page 146) . Evidently the
F2 purple plant w^as A a B bPlpl R^ /. The deviations from expecta-
tion are such as might occur by chance in about seventeen out of any
twenty such trials, P equaling 0.86. The comparison follows:

Plant Colors in Maize 83

Plant color Purple Purple Sun red Sun red

Anther color Purple Green Pink Green

la Ig Ila Ilg

Observed 28 13 11 3

Calculated 29 10 10 3

Dilute
purple

sun red ^^°^'^ ^reen Total

Purple

Pink Green Green

Ilia

IVa V IIIr, IVg ,VI

7

3 IG 11 02

10

3 13 14 02

Difference —1 +3 +1 0—3 0 +3 —3 0

The third purple-ant hered Fo purple tested, 29G1-3, gave in Fs all the
color types except dilute purple. Ilia, and dilute sun red, IVa. A purple
plant of the genotype AaBBPlplR^f should give the color types
observed. The observed deviations from expectation might occur by
chance about once in seven trials, P equaling 0.15. The comparison
follows:

Plant color Purple Purple Sun red Sun red Brown Green Total

Anther color Purple Green Pink Green Green Green

la Ig Ila Ilg V VI

Observed 37 11 5 2 12 3 70

Calculated 30 10 10 3 10 8 71

Difference +7 +1 —5 —1 +2 —5 — 1

A single green-anthered F2 purple, 2960-7, gave four F3 color types,
purple, sun red, brown, and green, all with green anthers. This behavior
is to be expected from an F2 genotype A a B B PI pi R^ R^. One of the
F3 purples, 4956-1, repeated this l)ehavior in F.i. The F3 and F4 progenies
are shown together in the following comparison, for which P = 0.60:

Color types Purple

Ig

Observed 84

Calculated 86

Difference —2 —2 +6 —2 0

It is of interest to note in this connection that a plant of the genotype
AaBB PlplR'^ R^ could not exhibit a 27:37 fatio of colored to color-
less aleurone, as was the case for some of the plants dealt with earlier.

Sun red Brown

Green

Total

Ilg V .

VI

27 35

7.

153

29 29

9

153

84 R. A. Emerson

For A a fl" R" the aleurone-color ratio must be either 9 : 7 or 3 : 1, depending
on whether the third aleurone-factor pair is C c or C C. The F2 purple
plant 2960-7 showed a 9:7 aleurone-color ratio with 86 colored and 74
colorless seeds, AaCcRR, while the F3 plant 4956-1 exhibited a 3:1
ratio with 213 colored and 67 colorless seeds, A aC C R R. Another
purple plant of the same F3 progeny, 4956-32, exhibited a 3 : 1 aleurone-
color ratio and threw only green-anthered purple and sun red plants. Its
genotype must have been A A B B C c Plpl R" R^. Thus it is often
possible, from behavior in the following generation, to know the genotype
not only with respect to plant color but for aleurone color as well. This
is particularly true when the B factor is present.

Of the twenty-four sorts of behavior possible, according to hypothesis,
for F2 purples of the cross under consideration, four sorts have been
exhibited in F3 and a fifth shown in F4. This is far from an adequate
study of the F2 purples. All that can be claimed, therefore, is that, so
far as they go, the results are in accord with the hypothesis.

Behavior of other F2 color types. — Only oie F2 sun red plant with pink
anthers, 2961^, was tested in F3. It produced sun reds with pink and
sun reds with green anthers, dilute sun reds, and greens. Since anther
color was noted for only a part of the plants, it has to be disregarded in
classifying the F3 progeny. The color types sun red, dilute sun red,
and green occurred in the numerical relation 114:23:57. Of the eight
possible genotypes of pink-anthered sun red, only three could throw
these three color classes — Aa B h/ /, A A B h R^ /, and Aa B h R" /.
From the first genotype a 9:3:4, from the second a 12:3:1, and from the
third a 36 : 9 : 19, relation should exist between the F3 classes. The poor
fit of observed numbers to the 9:3:4 relation makes it improbable that
the first genotype is concerned, there being only about one chance in
twenty-two that the ol^served deviations are due to errors of random
sampling, P equaling 0.045. The comparison follows:

Color types

Sun red
Ila

Observed. .

114

Calculated .

109

Difference.

+5

Green Total

Dilute

sun red

IVa Via, c

23 57 194

36 49 194

—13 +8 0

Plant Colors in Maize 85

A moro conclusive reason for throwing out the first genotype is the
fact that the phmt had some seeds with colored aleurone, which would
have been impossil)le if it were i- r. The second genotype is discarded
because of the extremely poor fit of observed numl)ers to the 12:3:1
relation. There is an almost inconceivably small chance that thc^ observed
deviations may be due to errors of random sampling, x- (equaling ISO.
(When n' = 3 and x~ = 29, P = 0.000001. Higher values of /' when iV - 3
are not listed in Pearson's tables.) The comparis:)n follows:

Color types Sun red ^'^^^*^ Green Total

sun red

Ila, g IVa IVg

Observed 114 23 57 194

Calculated 146 36 12 194

Difference —32 —13 +45 0

The elimination of the first two genotypes leaves the third genotype
as the only one that can be concerned here. The fit of observed numbere
to the 36 : 9 : 19 relation is very close, x^ equaling 0.84. (Values of P are
not listed in Pearson's tables for values of x- less than 1; when x^ = 1
and n' = 3, P = 0.6].) The comparison follows:

Color types Sun red J^}}""}^^

Ha, g

Observed 114

Calculated 109

Difference +5 — 4 — 1 0

This comparison leaves little doubt that the genotype of the F2 plant
concerned is AaBbR^/. There are, moreover, other considerations
which go far toward identifying the genotype as given here. The fact
that some sun red plants of F3 had green and others pink anthere is evidence
for the constitution R' /. Since dilute sun red plants appeared in F3,
there can be no question as to B h. The F2 plant showed a 9:7 aleurone-
color segregation, and therefore, in addition to R r, it must have been

rired ^^^^"

Total

:Va IVg, Via, c

23 57

194

27 58

194

g6 R. A. Emerson

either A a or C c. An F3 sun red plant with green anthers, R" R", had
97 colored and 20 colorless seeds, again indicating either A a or C c. If it
was A A B b C c R^ R'^, both colored and colorless seeds should have
given sun red and green plants in a 3:1 ratio; if it was A a B B C C R" R^,
the colored seeds should have given sun red and the colorless ones green
plants only, the plant-color ratio again being 3:1; but if it was A aBh
C C R^ R^, the colored seeds should have produced sun red and green
plants in a 3 : 1 ratio and the colorless seeds green plants only, the ratio
of sun reds to greens in the two lots together being 9:7. Actually the
colored seeds resulted in 23 sun red and 10 green plants and the colorless
seeds in 10 green plants only, the ratio of sun reds to greens being 23 : 20,
thus approaching 9:7. There is, therefore, considerable assurance that
the F3 plant was AaBhC C R^ i^^- that the Fa plant was AaBhC C
R^ /, and that the F3 numerical relation of plant colors was 36:9:19, as
originally suggested by the closeness-of-fit test.

A single dilute purple plant of F2, 2960-4, was tested in F3 and found
to give 38 dilute purple and 39 green plants. Of the eight possible geno-
types for F2 dilute purples, the only ones that could give only dilute
purples and greens in F3 are A A h h PI PI R^ /, A a h h PI PI / /, and
Aahh PIPIR^ /. The first two should give a 3:1, and the third a
9:7, F3 ratio. The plant had colored aleurone, which throws out of
consideration the second genotype with r r. The F3 plant-color ratio fits
fairly well a 9 : 7 but not at all a 3 : 1 expectation, the observed numbers
being 38 : 39 and the calculated numbers 43 : 34 and 58 : 19, with deviations
of 5 and 20, and probable errors of 2.6 and 2.9, respectively. The deviation
from a 9:7 ratio might occur by chance once in five trials, P equaling 0.20,
but that from a 3 : 1 ratio not more than twice in about a million trials,
P equaling 0.000002. The genotype AahhPlPlR"/ is therefore
decidedly favored by these results. The aleurone-color record shows that
this genotype is possible, since there were 57 colored and 56 colorless
seeds, a relation about halfway between the 9:7 and the 27:37 ratio
due io A aC C Rr and A a C c Rr, respectively.

Intercrosses of Fi color types

It is realized that the tests of Fo types by studies of their behavior in
later generations as reported above, are markedly inadequate to serve

Plant Colors in Maize 87

as a demonstration of the hypothesis suggested to account for the F2
behavior of the cross of brown, type V, with green, type IVg. It is note-
worthy, however, that no resuUs have been found that do not agree with
the hypothesis. Fortunately, several intercrosses of the types found in
F2 afford additional evidence.

Purple Ig x green Vic. — Green-anthered purples, A B PI RF, crossed
with greens of type Vic, a h pi f, should give F2 results identical with
those found from the original cross of brown, a B PI f, with green of
type IVg, A b pi R'', since Fi in either case should be A a B bPl pi R^ /.
Two such crosses are recorded in table 37, group 1 (page 146). The Fi
plants were both purple, with purple anthers. In F2 the same eight
t,ypes were noted as in Fo of the cross of brown with green IVg (table 36).
The anther color was not recorded, however, for many of the plants,
so that only six color classes are shown, as in table 35. While all the
expected color types are present, the fit of observed to calculated numbers
is so poor that the observed deviations should not occur by chance more
than once in thirty trials, P equaling 0.033. The comparison follows:

Color types Purple Sun red ^ ^,^ ^^ , Brown Green Total

-' ^ ^ purple sun red

la. g Ila, g Illa IVa V Illg, IVg, VI

Observed.... 80 13 9 9 20 27 158

Calculated... 66 22 17 6 22 25 158

Difference... +14 —9 —8 +3 —2 f2 0

If, notwithstanding the poor fit shown above, the Fi was A a B b PI
pi R" /, a backcross of Fi with green of type Vic, a b pi /, should result
in the same six major plant-color types, but no green-anthered purples
or sun reds should occur. Such crosses are listed in group 2 of table 37.
All the purple plants had purple anthers and all the sun red plants
had pink anthers. Moreover, the six color classes appeared in so very
nearly the expected relation of 1:1:1:1:1:3 that deviations as great as
those observed might be expected to occur by chance perhaps ninety-nine
times in one hundred trials, x^ equaling 0.85 (when x^ ~ 1 and n'- 6,
P = 0.96). The comparison follows:

88 11. A. Emerson

Color types Purple Sun red ^^^^^ g^^^ 'Jg^ Brown Green Total

la Ila Ilia IVa- V VI

Observed 36 29 31 31 31 95 253

Calculated 31.0 31.6 31.6 31.6 31.6 94.9 252.9

Difference +4.4 —2.6 —0.6 —0.6 —0.6 +0.1 +0.1

If an Fi supposedly A a B bPlpl R^ r-^, be backcrossed to dilute
sun red, type IVa, Ab pi /, color types la, Ila, Ilia, and IVa should
appear, none of them with green anthers. Such crosses are presented in
group 3 of table 37. The anthers thruout were purple or pink, and the
several color types appeared in approximately equal numbers, as expected,
there being more than two chances in five that the observed deviations
may have been due to errors of random sampling, P equaling 0.42. The
comparison follows:

Color types Purple Sun red ^'^^^^f^ ^^'^^""^^^ Total

la Ila Ilia IVa

Observed 115 97 95 111 418

Calculated 104.5 104.5 104.5 104.5 418

Difference +10.5 —7.5 —9.5 +6.5' 0

If the same Fi genotype, A a B h PI pi R" /, he backcrossed with
green of type IVg, A bplR", there should occur five major color types,
brown not appearing, and both green and colored anthers should be
found in ])oth the purple and the sun red plants. The records of such
a cross are given in group 4 of table 37. The seven expected color types
occurred in numljers near enough to expectation so that there are nearly three
chances in ten that the deviations may have been due to errors of random
sampling, P equaling 0.29. The most pronounced deviations are the excess
of dilute sun reds and the deficiency of greens. The comparison follows:

Plant color Purple Purple Sun red Sun red ^''"!® Dilute ^^^^ ,j,^^„j

^ ^ purple sun red

Anther color Purple Green Pink Green Purple Pink Green

la Ig Ila Ilg Ilia IVa Illg, IVg

Observed 10 i:j 7 S 10 15 1.3 76

Calculated .• 9.5 9.5 9 5 9.5 9.5 9.5 19 76

Difference +0.5 +3.5 -2.5 —1.5 +0.5 +5.5 —6 0

Plant ( ulous in Maize 89

In conclusion it seems safe to say that the cross of gi'een-anthered
purpl(\ Ig, with green of type Vic, havS given results similar to those
yielded by the cross of brown. V, with green of type IVg. Since this
was to have been expected from the hypothesis suggested by the F2
generation of the latter cross, the results just discussed lend support to
that hypothesis.

Purple Ig x dilute sun red IVa. — In accordance with the hypothesis
under consideration, green-anthered purple is A B PI R^ and dilute sun
red is A h pi /. Fi of the cross should he A A B b PI pi P!' /, and F2
should consist of the five major color types, purple, sun red, dilute purple,
dilute sun red, and green of types Illg and IVg, with both green-anthered
and colored-anthered subclasses of purples and sun reds. The Fi plants
were purple-ant hered purples, as expected. Three F2 progenies are
recorded in table 3$, group 1. Anther color could not be recorded in
all cases, but in each of the three F2 progenies both green and colored
anthers were noted for both purple and sun red plants. In one progeny,
5042-5045, of a total of 57 purples and sun reds, 41 had colored and 16
had green anthers, which is not far from the expected 3 : 1 relation. The
415 F2 plants w^re so distributed among the five color classes that the
chances are nearly three in five that the deviations observed may have
been due to errors of random sampling, P equaling 0.58. A comparison of
observed and theoretical distributions follows:

Color tvpes Purple Sun red 1 , Green Total

^ ^ ^ purple sun red

la, g Ila, g Ilia IVa IHg, IVg

Observed , 243 71 59 22 20 415

Calculated 234 78 58 19 26 415

Difference +9 —7 +1 +3 —6 0

An Fi of the cross here considered, 6557-12, A A Bh Pi pi R" /, was
backcrossed to a dilute sun red, A b pi /. Four color types occurred in
the progeny, as expected, and all the plants had colored anthers. The
deviations from expectation were such as might occur by chance in consider-
ably more than one out of any two such trials, P equaling 0.56. The
comparison follows:

R. A. Emerson

Purple Sun red

Dilute
purple

Dilute
sun red

Total

la Ila

Ilia

IVa

43 43

35

48

169

42 42

42

42

168

90

Color types

Observed "

Calculated

Difference +1 +1 —7 +6 +1

Purple la x green IV g. — The cross between purple la and green IVg
should have given results identical with those expected from the cross
of green-anthered purple with dilute sun red. Tho parents are supposed
to have been A BPl/ and A b pi R\ and the Fi, therefore, A A B h PI
pi R^ /. The Fi's were purple-anthered purples. Two r2 progenies are
listed in table 38, group 2. All the expected color -types occurred, but
the observed frequency distribution was such as might be expected to
occur by chance only about once in eleven trials, P equaling 0.09. If
these progenies are grouped into five classes, anther color being disregarded,
the fit is somewhat better, P equaling 0.16. The comparison of observed
and theoretical frequencies follows:

Plant color Purple Purple Sun red Sun red ^^^^^f ''^'^"H Green Total

^ ^ purple sun red

Anther color Purple Green Pink Green Purple Pink Green

la Ig Ila Ilg Ilia IVa Illg, IVg

Observed 26 14 17 3 9 2 1 72

Calculated: 31 10 10 3 10 3 5 72

Difference —5 +4 +7 0 — 1 —1 —4 0

The F2 of this cross exhibited, as expected, practically the same results
as were obtained from the cross of green-anthered purple with dilute
sun red. Unlike that cross, the one under consideration here was checked
by the behavior of some of its F2 types in later generations.

A single F2 purple-anthered purple produced in F3 16 plants (table 39,
group 1), including only purple, sun red, and dilute purple in the relation
9:4:3. Of both the purples and the sun reds, some plants had colored
and some had green anthers. Obviously two other types, dilute sun red and
green, should occur in such an F3 and doubtless would have been found
had a larger number of plants been grown, for the F2 plant, in order to have
produced the color types recorded, must have been A A B b Plpl R' /.

Plant Colors in Maize 91

Only one plant of each of the missing classes was to have been expected,
and the distribution as a whole was not far from expectation, P equaling
0.59. Both the types lacking in F3 occurred in F4, a pink-anthered sun
red F:i producing sun reds and dilute sun reds, while green-anthered
purples produced in one instance purples, sun reds, and greens, and in
another instance purples and greens only, all with green anthers. This
F3 lot may consequently l)e regarded as A A B b PI pi R" /, and therefore
equivalent to the F2 lot from which it came, and its F4 progenies equivalent
to F3 progenies.

A second F2 purple-anthered purple was backcrossed to green plants
of types IVg and Vic (group 1, table 39). From the backcross with green
of type IVg, Ab pi R^, five major color types appeared and both the
purple and the sun red types contained subtypes with colored and with
green anthers. While all the classes expected from an F2 of the genotype
A A Bb PIpIR^ / occurred, the frequency distribution was so far
from expectation that there is only one chance in five hundred that the
observed deviations may have been due to errors of random sampling, P
equaling 0.002. The expected and observed distributions are as follows:

Color types Purple Sun red ^'^"t^ ^'^''^^ Green Total

•^ ^ ^ purple sun red

Ia,g Ila, g Ilia IVa Illg, IVg

Observed 15 15 5 1 9 45

Calculated 9 9 9 9 9 45

Difference +6 +6 —4 —8 0 0

Whether the discrepancy is genetically significant or was due to some acci-
dent of pollination cannot now be determined. A backcross of the same F2
plant with green of type Vic, ab pi /, yielded only four color types, as
expected (group 1, table 39), the anthers being colored in all cases. The
excess of purples and deficiency in two other classes makes the deviations
from expectation fairly great, so that there is only about one chance in
seven that they may have been due to errors of random sampling, P
equaling 0.14. The comparison follows:

92 R. A. Emerson

Color types Purple Sun red ^^^^ ^^ Total

la Ila Ilia IVa

Observed 27 19 15 14 75

Calculated 19 19 19 19 76

Difference +8 0 —4 —5 —1

A third purple-anthered purple, an F- plant of the lot regarded as
equivalent to Fo's, gave in the next generation purple-anthered purples
and pink-anthered sun reds in the relation 31:7 (group 2, table 39). From
the genotype A A B B PI pi //, these two phenotypes should appear
in a 3:1 ratio. The deviation from expectation was 2.5 ± 1.8, or only
such as might be expected about once in three trials, P equaling 0.34.

Two green-anthered purples of F2 and two of the equivalent F3 lot
noted above were tested by a later generation. Two of the four yielded
three color tj^jes, purple, sun red. and green, all with green anthers (group 3,
table 39). Such behavior is expected from the genotype A A B b PI
pi R^ R^. The 9:3:4 relation is approached so closely that the value
of P cannot be determined from Pearson's tables, x^ equaling 0.36. The
comparison follows:

Color types Purple Sun red Green Total

Purple

Sun red

Green

Ig

Ilg

Illg, IVg

37

11

14

36

12

16

Observed 37 11 14 62

Calculated 36 12 16 64

Difference +1 —1 —2 —2

The same two .green-anthered purples were backcrossed with green
of type IVg, and one of them and a sib of the other with green of tj-pe
Vic, with results as shown in group 3 of table 39. The crosses with type
IVg, AhplI^, gave the same three classes as did the self-pollinations,
and the frequency distribution differed from expectation by values that
might occur by chance about once in two trials, P equaling 0.49. The
comparison follows:

N Maize

93

Sun red

Green

Total

Ilg

nig, ivg

32

53

119

30

60

120

Color types Purple

Ig

Observed 34

Calculated 30

Difference +4 +2 —7 —1

The backcrosses of these green-anthered purples with green of type Vic,
a b pi /, as was to be expected, gave very different results. There were
produced four instead of three phenotypes, all with colored (purple or
pink) instead of green anthers. The deviations from the theoretical
frequency distribution are such as might be expected about once in five
trials, P equaling 0.21. The comparison follows:

Color types

Observed

Calculated

Purple
la

Sun red
Ila

Dilute

purple

Ilia

Dilute

sun red

IVa

Total

44

44

48
44

33

44

52
44

177
176

Difference 0 +4 —11 +8 +1

The other two green-anthered purples that were tested yielded only
two phenotypes, green-anthered purple and green, in the relation 56:18
(group 4, table 39). The genotype AABhPlPlRUi' should give
these two phenotypes in a 3 : 1 ratio. The deviation from expectation
was therefore 0.5 ± 2.5. One of the same plants backci-ossed to green
of type IVg gave 28 green-anthered purples and 27 greens where equality
was expected.

Of the twelve kinds of behavior expected of F2 purples of the cross of
purple-anthered purple with green IVg, only four have been demonstrated.
So far as they go, however, the results are quite in accord with the hypoth-
esis under test. In addition to the F2 purples, sun reds and dilute
purples also were tested by later generations, as detailed below.

Three pink-anthered sun reds gave sun reds and dilute sun reds only,
all with pink anthers (table 40, group 1). These three plants are therefore
regarded as A A Bh pi pi//. The ratio observed was 97:26. The
deviation from the expected 3:1 ratio was 4.75 it 3.24, or such as might

94 R. A. Emerson

occur by chance once in three trials, P equahng 0.32. One of these three
sun reds, when crossed with a dilute purple, Ah PI/, gave 71 purples
and 77 dilute purples, all with purple anthers, where equal numbers were
expected.

Three other F2 pink-anthered sun reds produced nothing but sun red
plants in F3, 228 in all (group 2, table 40). Some plants of each progeny
had pink and some had green anthers. Small plantings of each lot were
made in the garden and larger plantings in the field. Anther color was
noted in the case of the garden plants only. The records show 44 with pink
and 16 with green anthers, a deviation from a 3: 1 ratio of only 1.0 ± 2.3.
The F2 sun reds are therefore assumed to have been A A B B plpl R^ /.
One of these F2 plants was backcrossed to green, both of type IVg and
of type Vic, resulting in a total of 108 sun red plants (group 2). Altho
no counts were made for anther color, it was noted that the cross with
green IVg, Ah pi R^, gave both pink- and green-anthered plants, while the
cross with green Vic, ah pi /, gave pink anthers alone. Only t'^^o of the
six possible genotypes of F2 sun reds were demonstrated.

Only one dilute purple F2 plant was tested further (group 3, table 40).
From self-pollination it yielded 46 dilute purple and 9 dilute sun red
plants, all with colored (purple or pink) anthers. The deviation from
a 3:1 ratio, 4.75 ± 2.17, is such as might be expected by chance about
once in seven trials, P equaling 0.14. The same F2 plant when back-
crossed to green of types IVg and Vic (group 3) gave 85 dilute purples and
82 dilute sun reds where equality was expected. Evidently this F2 was
A A hh Plplf /.

No F2 dilute sun red or green plants were tested further. One F3
dilute sun red, however, was found to breed true, producing an F4 of 30
pink-anthered dilute sun reds. Likewise, eight F3 and F4 greens gave
a total of 126 green plants in the next generation.

In so far as tests have been made, therefore, the cross of purple-anthered
purple with green IVg has behaved as expected on the basis of the hypo-
thetical genotype assigned to Fi, namely, A A B bPlplR^ /.

Purple Ig x green I Vg. — Green-anthered purples are assumed to be
A B PI R^, and green IVg to be A 6 pi R^ . The Fi genotype is therefore,
theoretically, A A B b PlplR^ R^, and F2 should consist of the three
color types purple, sun red, and green, all with green anthers. Eight
such F2 progenies are recorded in table 41, group 1. The three types

Plant Colors in Maize 95

occurred in so nearly the expected relation of 9:3:4 that the observed
deviations might be expected by chance considerably more than once in
three trials, P cquahng 0.37. The comparison follows:

Color types Purple Sun red Green Total

Ig Ilg Illg, IVg

Observed 293 105 150 548

Calculated 308 103 137 548

Difference —15 +2+13 0

The F2 greens of this cross are assumed to consist of the genotypes
Ah PI R' and Abpl R^, which, if / had been present instead of R'^,
would have been dilute purples and dilute sun reds, respectively. In
substantiation of this assumption, crosses of Fi's, all green-anthered
purples, with dilute sun red, A b pi /, and with green Vic, ah pi /, are
recorded in group 2 of table 41. As expected, the result was the four
classes purple, sun red, dilute purple, and dilute sun red, all with colored
anthers. The expected numerical equality of the four classes was so
closely approached that deviations such as those observed might be
expected by chance in nearly three out of four trials, P equahng 0.74.
The comparison follows:

Color types Purple Sun red ^^^ ^^"^"^^^ Total

la Ila Ilia IVa

Observed 58 61 62 70 251

Calculated 63 63 63 63 252

Difference —5 —2 —1 +7 — 1

Still another Fi was crossed with a pink-anthered sun red, A B pi /,
and gave 68 purples and 67 sun reds, all with colored anthers, where
equal numbers were expected.

So far as tested, therefore, the cross of green-anthered purple with
green IVg has given the results expected on the basis of the hypothesis
under test.

Purple Ig x brown V.— A cross of green-anthered purple, A B PIR^,
with brown, a B PI /, gave in Fi 49 purple-anthered purples, presumably

4

96 R. A. Emerson

A aB B PI PI R^ /. An r2 progeny was grown from only one Fi plant,
6653-6, resulting in two major color types, purple and brown, in approxi-
mately a 3 : 1 ratio. The purples were, as expected, of two subtypes,
one with purple and the other with green anthers. The theoretical rela-
tion of 9:3:4 was realized so closely that the observed deviations might
be expected by chance in at least two out of three trials, x^ equaling 0.76
(when z'=l and n' = 3, P = 0.61). The comparison follows:

Color types. f^^'P}?' ^^'Plf Brown Total

•^ ^ purple anthers green anthers

la Ig V

Observed 23 5 9 37

Calculated 21 7 9 37

Difference +2 —2 0 0

A second Fi plant, 6653-2, was backcrossed with green IVg, Abpl R^,
resulting in 39 purple plants, 21 with purple and 18 with green anthers,
where equal numbers were expected, the deviation from expectation being
1.5 ± 2.1. The same Fi plant was crossed with a heterozygous dilute
sun red, A abb pi pi / /, resulting in 45 purple-anthered purples and
18 browns, the deviation from the expected 3:1 ratio being 2.25 db 2.32.

Purple Ig x dilute purple Ilia. — Crosses of green-anthered purple,
A B PI R^, with dilute purple, Ab PI /, gave in Fi purple-anthered
purple, A A B b PI PI R^ /. The F2 should consist of purple-anthered
and green-anthered purples, dilute purples, and greens, the three major
color types appearing in the relation 12:3:1. In F2 from a single Fi
plant, 5263-3, both purple-anthered and green-anthered purples were
noted, but detailed counts based on anther color were not made. The
deviations from the expected numbers for the three major types were
such as might occur by chance in nine out of twenty such trials, P equaling
0.45. The comparison follows:

Color types Purple ^^^\l Green Total

la, g Ilia Illg

Observed 36 11 5 52

Calculated 39 10 3 52

Difference —3 +1 +2 0

Plant Colors in Maize 97

A second Fi plant backcrossecl with green IVg, A b pi R", gave the
expected four types. The deviations from the equal frequency expected
for the several types was such as might occur by chance somewhat more
than once in four trials, P equaling 0.27. The comparison follows:

Color Purple, Purple, Dilute

types purple anthers green anthers purple

la Ig Ilia

Observed... 59 67 80

Calculated.. 71 71 71

Green

Total

Illg

77

283

71

284

Difference.. —12 —4 +9 +6 — 1

Dilute purple Ilia x green IVg. — A single cross of dilute purple,
Ah PI /, with green I\'g, A b pi K', gave dilute purple, A Abb PI pi R^ /,
in Fi, and three phenotypes, dilute purple, dilute sun red, and green, in
F2 (table 42, group 1, page 150). The observed frequencies were 23 :8: 10,
which is the nearest possible approach to the expected 9:3:4 relation for
a total of 41 individuals. One Fz- dilute purple gave similar results in F3,
indicating the same genotype as the Fi dilute purples. The F4 progenies
of this F3 lot may be regarded as equivalent to Fa's, and are, therefore
grouped with the F3 in table 43. Three F3 and F4 progenies (table 43,
group lA) approached the 9:3:4 relation so closely that the observed
deviations might occur by chance in nearly three out of five trials, P
equaling 0.59. The comparison follows:

Color types ^^^^1^ ^^^t^. Green Total

•^ ^ purple sun red

Ilia IVa Illg, IVg

Observed 143 48 73 264

Calculated 149 50 66 265

Difference —6 —2 +7 —1

The green plants of these F3 and F4 lots, as well as those of the F2 lot
listed in group 1 of table 42, are assumed to be Ab Pi R" and Abpl R",
and consequently to differ from the dilute purples and dilute sun reds only
in having R'^ RF in place of R^ / or / /. That the R r pair is thus con-
cerned in these results can be shown ])y a comparison between the plant-

98 R. A. Emerson

color phenotypes resulting from seeds with colored aleurone and those
from seeds with colorless aleurone. The Fo progeny came from a plant
that produced from self-pollination colored and colorless seeds in the
relation 60 : 24. This close approach to a 3:1 ratio indicates that the
Fi plant could have been heterozj^gous for only one of the aleurone-factor
pairs A a, C c, or Rr (Emerson, 1918). A cross with a C tester, A c R,
resulted in 43 colored and no colorless seeds, while a cross with an R
tester, A C r, gave 46 colored and 32 colorless seeds, thus indicating R r
as the factor pair concerned. The colorless seeds must therefore have
been r r, presumabl}^ / /, and in accordance with the hypothesis under
test should have produced no gre^i plants. Some of the colored seeds,
on the contrary, should have been R R, supposedly R^ R^, and these
should have given green plants. For the most part, the colored and the
colorless seeds were planted separately. The 9:3:4 relation of the three
plant-color types is theoretically made up of a 6:2:4 relation from colored
seeds and a 3:1:0 relation from colorless seeds. Actually, from colorless
seeds there appeared dilute purple and dilute sun red plants in the ratio
69:15. The deviation from expectation, 6.0 ± 2.7, might be expected to
occur about once in seven trials, P equaling 0.14. From colored seeds
the deviation from the theoretical distribution was such as might occur
thru errors of random samphng almost once in four trials, P equaling
0.23. The comparison follows:

Dilute Dilute
sun red

Color types ^^^ *^

'' ^ purple

Ilia IVa

Observed , 92 42

Calculated 102 34

Green

Total

Illg, IVg

70

204

68

204

Difference —10 4-8 +2 0

Aleurone is in some cases self-colored and in some cases mottled.
Mottled aleurone ordinarily occurs only when the R factor is heterozygous,
but not all heterozygous individuals are mottled (Emerson, 1918).
Mottled seeds of the cross under discussion, just as colorless ones, since
they are presumably R^ /, should produce no green plants. In the
case of some of the progenies noted above, the colored seeds were sorted
into self-colored, mottled, and colorless. Since usually about one-third

Plant Colors in Maize 99

of the colored seeds arc mottled, the 9:3:4 relation of plant-color types
observed in this cross should be made up of a 3:1:0 relation from color-
less seeds, 3:1:0 from mottled seeds, and 3:1:4 from self-colored seeds.
Of the progenies for which the seeds were sorted in this way, the color-
less seeds produced dilute purple and dilute sun red plants in the relation
60: 14, with a deviation from 3: 1 of 4.5 db 2.5, the mottled seeds gave the
same plant-color types in the relation 30: 12, with a deviation of 1.5 ± 1.9,
and the self-colored seeds yielded dilute purple, dilute sun red, and green
in the relation 48:19:64 (the theoretical distribution for a total of 131
individuals is 49:16:66), the deviations being such as might occur by
chance perhaps three times in four trials, z^ equaling 0.64. On the whole,
therefore, these crosses, and particularly the interrelations of aleurone and
plant colors, afford strong evidence in support of the hypothesis under test.
Before presenting further F3 results from these crosses, it may be well
to consider other crosses of dilute purple with green IVg which, so far as
plant color alone is concerned, have given results quite like those pre-
sented above but which exhibit a wholly different relation between plant
color and aleurone color. The green plants concerned in these other
crosses were C testers for aleurone color (Emerson, 1918), and were there-
fore known to be A c R, presumably A c B?. The dilute purple plants
concerned were homozygous for aleurone color, and were consequently
A C R, presumably A c R^. These crosses differ, then, from the ones
discussed above in having R^ in place of r" and c in place of C. Since the
C c pair is supposed not to have any relation to plant color, the results for
plant color should be quite like those for the other cross and there should
be no relation between plant color and aleurone color. The results for
F2 are presented in table 42, group 2, and the F3 results in table 43,
group IB. The three plant-color types appeared in F2 in the relation
328:113:148, and in F3 in the relation 40:14:23. Considered together
these lots deviated very slightly from expectation, x~ equaling 0.31. The
comparison follows:

Color tvDes ^^^"1^ ^'^"^'', Green Total

»^oior Types purple sun red

Ilia IVa Illg, IVg

Observed 368 127 171 666

Calculated 375 125 166 666

Difference —7 +2 -\-d 0

100 R. A. Emerson

The seeds from which these plants were grown consisted of colored and
colorless in approximately a 3 : 1 ratio, as is expected when the C factor
alone is heterozygous. The deviations from the expected 9:3:4 relation
for plants from colored seeds was such as might occur by chance more than
once in three trials, P equaling 0.36, and for plants from colorless seeds
such as might occur once in six trials, P equaling 0.17. The comparisons
follow :

Plant-color types ^^^ ^J^^^ Green Total

Ilia IVa Illg, IVg
Colored seeds:

Observed 215 58 89 362

Calculated 204 68 90 362

Difference +11 —10 —1 0

Colorless seeds:

Observed 65 32 32 129

Calculated 73 24 32 129

Difference —8+8 0 0

The resvilts presented for plant color alone and in relation to aleurone
color in these crosses are therefore quite in keeping with the hj'^pothetical
constitution assigned to the Fi plants, namely, AAhhPlplKR'Cc,
just as the results from the other crosses were in keeping with the assumed
genotype AAbhPlplR'/CC for their Fi plants.

A single Fi plant was backcrossed with green IVg, Ah pi R\ with
results as shown in table 42, group 3. The three color types dilute purple,
dilute sun red, and green, occurred in the relation 46:45 : 86. The expected
distribution for a total of 177 individuals is 44:44:89, showing almost a
perfect fit, x- equaling 0.21.

For both the lots of crosses under discussion, further tests are afforded
by the behavior in F3 and F4. As already shown, some of the F2 dilute
purples had the same genetic constitution as the Fi plants (table 43,
groups lA and IB). The progenies of two other dilute purples, one of
F2 and the other of an equivalent F,-?, produced dilute purple and dilute
sun red plants only (group 2, table 43), in the relation 82:23. The devia-

Plant Colors in Maize 101

tion from a 3:1 ratio is 3.25 ± 2.99. From their behavior and in viow
of the crosses in which they occurred, one of these plants is assumed to
have been A Abb PI pi /V and the other A Abb PI pi R' R\

A single dilute purple of an F? lot equivalent to an F2 gave dilute purple
and green plants only (group 3, table 43). The two color types appeared
in the ratio 62:16, a deviation from 3:1 of 3.5 ± 2.6. The Fj plant is
therefore assumed to have been A Abb PI PI R" /. Colorless and
mottled seeds produced dilute purple plants only, as was expected. From
self-colored seeds there resulted dilute purple and green plants in the
relation 26:16, a deviation of 2.0 ± 2.0 from the expected 2:1 ratio.

Two dilute sun red plants gave progenies of dilute sun reds and greens
in the relation 63:22, a deviation from a 3:1 ratio of 0.75 ± 2.69 (group
4, table 43). Presumably these plants were A Abb pi pi R"/ and
A Abb pi pi R'' R^. Four other dilute sun red plants bred true in the
next generation (group 5, table 43), producing a total of 197 dilute sun
red plants. These plants are therefore assigned the genotype A Abb pi
pi / /.

Seven green plants likewise bred true (group 6, table 43), producing a
total of 130 green plants. These plants were presumably Abpl R^ and
AbPl R\

To summarize, all types of behavior were observed in F3 and equivalent
F4 generations of the cross of dilute purple with green IVg except true-
breeding dilute purples. Only eight dilute purples were tested, and only
one in nine is expected to breed true.

Sun red 11 g and 11 a and dilute sun red IV a x green Illg and IVg. — Two
crosses of green-anthered sun red with green IVg gave green-anthered
sun red plants in Fi, theoretically A A B b j)l pi R' R^. The parent
types only appeared in F2 (table 44, group 1). The observed numbers
of green-anthered sun reds and greens were, respectively, 216 and 77.
The deviation from the expected 3:1 ratio was 3.7 5zb 5.00.

A cross of pink-anthered sun red with green IVg gave pink-anthered
sun red in Fi, theoretically A A Bbplpl R^ /. Fi plants backcrossed
with green IVg, A b pi R\ gave three major plant-color types (group 2,
table 44) — sun red, dilute sun red, and green — with the sun reds appear-
ing in two subtypes, one pink-anthered and the other green-anthered.
Theoretically the four types should have been represented by an equal
number of individuals. The deviations from this expectation were such

102 R.. A. Emerson

that there is considerably more than an even chance that they might
have been due to errors of random sampHng, P equaling 0.56. The
comparison follows:

^ 1 , Sun red, Sun red, Dilute ^ rr„+„i

Color types pi^k anthers green anthers sun red ^'^^^ ^^^^^
Ila Ilg IVa IVg

Observed 105 90 105 109 409

Calculated 102 102 102 102 408

Difference +3 —12 +3 +7 +1

Crosses of dilute sun red with green IVg gave 54 dilute sun red plants in
F], A A hhplplR^ /. In F2 (group 3, table 44) there resulted from a
self-pollinated Fi, dilute sun red and green plants in the relation 55:22,
a deviation from the expected 3:1 ratio of 2.75 ± 2.56. An Fi back-
crossed with green IVg gave the same two color types in equal numbers,
30 each, exactly as expected. Numerous other crosses of this sort have
been observed in connection with studies of the interrelations of aleurone-
color and plant-color factors. Since these data are to be presented in a
later paper and since they are wholly in accord with the data given in
group 3 of table 44, they are not discussed here.

In an earlier section of this paper dealing with the factor pairs A a,
B b, and PI pi only (page 29), it was shown that the green plants there
noted are of three kinds, namely, abpl, a B pi, and a b PL Thruout
the present section of the paper, which deals with the relation of the
multiple-allelomorph series containing R", r\ K^ r\ it has been assumed
that plants which in the presence of / or R^ are dilute purple or dilute
sun red, are green in the presence of homozygous R^. The data presented
are wholly in accord with this interpretation, thereby giving considerable
assurance of the probable correctness of the hypothesis. The reported
interrelations of plant color and aleurone color when the latter was known
to involve the R r pair, have still further strengthened this assurance. It
remains now to present even more direct evidence, namely, that obtained
from crosses of green plants encountered in this study, with sun red and
dilute sun red plants. These green plants are assumed to be A 6 PI R^,
type Illg, and Abpl R\ type IVg.

Certain F3 and F4 progenies consisting of green-anthered purples and
greens in a 3: 1 relation are listed in table 39, group 4. These green plants

Plant Colors in Maize 103

were all. presumably, A b PI /?". Green plants of a later generation,
grown from these greens, when crossed with sun red plants, type Ila, gave
64 purple-anthered purples and no other types (table 45, group 1).
Another green crossed with dilute sun red resulted in 4 dilute purples.
Obviously the same results would have been obtained had the green plants
used in these crosses been ah Plr^, instead of A 6 P/ 7^" as they are sup-
posed to have been. As a matter of fact, however, one of these green
plants had homozygous colored aleurone, and therefore must have been
A C R. The other two greens, while they had colorless aleurone, came from
lots known, from their 3:1 aleurone-color ratios and from crosses with
aleurone testers, to be heterozygous for C alone, and therefore A c R.
Moreover, the green plants from lots consisting of purples and greens in a
3 : 1 relation could not have been a a, for the parents of such lots, if hetero-
zygous for A, must have produced purples and browns rather than purples
and greens. The green plants could therefore have been nothing other
than A b PI R'.

Similarly, progenies consisting of green-anthered purples and sun reds,
and greens, in a 9:3:4 relation, are hsted in table 39, group 3. Green
plants of these lots and their green descendants might be either Ab PIR^
or A b pi R", or might be heterozygous for PL Six such green plants were
crossed with dilute sun reds (table 45, group 2). None of these greens
could'have been of the types discussed in the earlier section of this paper,
namely, ah PI/ and the like, for they were shown b}^ appropriate tests
(Emerson, 1918) to he A c R and some of them have even been used as
C testers for aleurone color. Two of these green plants crossed with dilute
sun reds gave dilute sun reds only, 59 in all, and are consequently regarded
as being Ah pi R^. Two others by sunilar crosses gave dilute purples
and dilute sun reds in the relation 20:30, a deviation of 5.0 ±2.4 from the
expected equality from plants of the genotype A Abb PI pi R" R".
Two other greens were crossed with heterozygous dilute sun reds,
A Abb pi pi R'^ /, and gave dilute purples, dilute sun reds, and greens
in the relation 69:54:106. The theoretical distribution among these
three classes for a total of 229 individuals, based on the assumption that
the green parent plants were A Abb Pi pi R" R\ is 57:57:115, a devia-
tion that might occur by chance about once in five trials, P equaUng 0.19.

Progenies consisting of dilute purples, dilute sun reds, and greens in a
9:3:4 relation are listed in table 43, group lA. Descendants of one of

104 R. A, Emerson

these green plants were crossed with dilute sun reds which were Fi's of
crosses between dilute sun red and green IVg. The results were dilute
purple and green plants in the relation 328:338 (table 45, group 3), a
deviation from a 1 : 1 ratio of 5.0 ± 8.7. Since the heterozygous dilute
sun red plants were A Ah h pi pi R^ /, the green plants crossed with them
are assumed to have been A b PI R^. That this assumption is correct
appears the more evident from the fact that the green plants were homo-
zygous for colored aleurone, and hence A C R.

Green IVg x green Vic. — Twelve crosses between green plants of type
IVg and green plants of type Vic gave a total of 159 Fi plants, all dilute
sun red. With respect to aleurone color, all the type IVg plants concerned
in these crosses were known to be A c R, and, in fact, were in general
use as C testers for aleurone color. With respect to plant color, therefore,
they are assigned the constitution Ahpl R^. Of the type Vic greens,
four were known to be A testers for aleurone color, and were therefore,
with respect to aleurone color, a C R. Their plant-color constitution is
accordingly set down as ahpl R^. Six of the type Vic greens had an
aleurone-color constitution of aC r, their plant-color genotype being
accordingly ahpl /. The other two Vic greens were certainly a b pi,
but whether they were R'^ or / is unknown.

In Fa, dilute sun red and green plants were present in the ratio 420:291
(table 46, group 1, page 154). From an Fi of the genotype A ahh pi pi
plus* R^ / or R^ R^, a 9 : 7 ratio of dilute sun red to green is to be expected
in F2, since both A and / or R^ are assumed to be necessary for the pro-
duction of anthocyanic pigment, which distinguishes dilute sun red from
green. The theoretical ratio for a total of 711 individuals is 400:311.
The observed deviation from this ratio, 20.0 ± 8.9, is such as might
occur by chance about once in eight trials, P equaling 0.13.

Two Fi plants backcrossed to green Vic, a h pi R^, gave 66 dilute sun
red and 58 green plants, and two backcrosses with green IVg, A h pi r^,
gave 96 dilute sun reds and 96 greens, equality of the two classes being
expected in the case of both crosses (group 2, table 46).

That the two parent types of green occurred in F2 is shown by their
relations to aleurone and pericarp color. In the case of every cross, green
plants were produced from both colored and colorless seeds. Those
from colored seeds could have been only A h pi R^. Since some seeds
were colorless because of a a and some because of c c, both parent types of
green should have been present in the lots grown from colorless seeds.

Plant Colors in Maize 105

In one cross there was prosont tho pericarp factor P, which with A gives a
red and with n a a l)rown pericarp. All the F2 green plants from colored
seeds had red pericarp, and of those from colorless seeds the majority had
brown pericarp. From the colorless seeds there should have occurred
also a conil)ination type of green, a b pi W, but no tests were made for
the identification of this type.

Ten dilute sun reds of F- were tested by their F3 behavior. Three
of these (table 47, group 1) gave dilute sun red and green plants in the
relation 108 : 77, a deviation from a 9 : 7 ratio of 4.0 ± 4.6. Five other
F2 plants (group 2) gave the two color types in the relation 187:66, a devia-
tion from a 3 : 1 ratio of 3.0 ± 4.6. Two F2's (group 3) bred true dilute
sun red, producing 78 dilute sun red and no green offspring. Theoretically,
of 9 Fo dilute sun reds, there should occur in F3, true-breeding, 3:1,
and 9:7 progenies in the numerical relation 1:4:4, The observed rela-
tion between these three sorts of l^ehavior for the ten F2's tested was
2:5:3. Deviations such as these might occur by chance about once in
two trials, P equaling 0.49.

Green IVg x green Via. — Certain crosses of green IVg with green \I
have given sun red plants in Fi. The t^^pe VI greens belonged to families
in which the B factor was known to be present. They were therefore
doubtless a B pi plus / or R\ and the Fi's were probably A a B b pi pi
plus / R^ or R" R^. F2 consisted of the three major color t^'pes sun red,
dilute sun red, and green (table 48, group 1) in the relation 586:161:348.
Obviously this is not a 9 : 3 : 4 relation, for the deviations from such expecta-
tion, -30, -44, +74, could not be expected to occur thru errors of random
sampling once in a million such trials, z^ equaling 30.9 and P equaling
.000000+. As a matter of fact, an Fi of the genotype suggested above
should give in F2 the three color types observed in the relation 36:9:19.
The observed frequencies of the several classes fit this expectation so
closely that the deviations from it might occur by chance in about one
out of five trials. P equaling 0.19. The comparison of observed and
expected frequencies follows:

Color types Sun red g^^^ ^.^^ Green Total

Ila, g IVa IVg, Via, c

Observed 586 161 348 1 ,095

Calculated 616 154 325 1 .095

Difference —30 +7 +23 0

106 R. A. Emerson

Not only were the frequencies of the major color types fairly close to
expectation, as indicated above, but the expected subclasses of sun red with
pink anthers and with green anthers were observed. Counts of anther
color were made -in the case of only 65 individuals. These plants were
distributed to the four color classes, pink-anthered sun red, green-anthered
sun red, dilute sun red, and green, in the order 24:9:10:22. The
theoretical distribution of 64 individuals being 27:9:9:19, the deviations
are such as might occur by chance perhaps twice in three trials, z^ equaling
0.91 (when x^ = 1 and n' = 3, P = 0.61).

Only three Fa sun reds were tested in F3. One of them (group 2, table 48)
bred true sun red, but segregated with respect to anther color. It was there-
fore presumably A A B B pi pi/ R''. Two other F2 sun reds (group 3)
gave sun red and green offspring in the ratio 229:71, a deviation of only
4.0 ± 5.1 from a 3:1 ratio. One of these two F2 plants was crossed
with a dilute sun red, resulting in 55 sun red plants. The two F2 plants,
therefore, were presumably A a B B pi pi. Anther color was not deter-
mined, but the fact that the green plants of F3 all came from colorless
seeds is conclusive evidence for the presence of 4 a and against the pres-
ence of / R^. The genotype of the F2 plants is accordingly set down as
AaBBplpl / /.

Green Illg x green Vic. — Green plants known to be of type Vic, ah pi /,
were crossed with greens which were known to be R^ R^ and which from
their parentage might have had Pi. The result in Fi was dilute purple,
supposedly A ah h PI pi f R^. Two F2 lots (table 49, group 1) consisted
of dilute purples, dilute sun reds, and greens in the relation 109 : 37 : 135.
From the assumed genotype of Fi, there should occur in F2 the observed
color types in the relation 27:9:28. The observed frequencies deviated
from the theoretical ones by amounts such as might occur by chance
once in three trials. P equaling 0.33. The comparison follows:

ri 1 2. Dilute

Color types ^^^^^^^

Ilia

Observed 109

Calculated 119

Difference —10 —3 +12 — 1

Dilute ^
sun red ^'^^^"

Total

IVa Illg, IVg, Ylb, c

37 135

281

40 123

282

Plant Colors in Maize 107

The dilute purples of F2 were presumably all A b PI / and the dilute
sun reds all A b pi /. Of the Fo greens there should theoretically have
been six types, namely, AbPlR^, AbplR", abPl/, ah pi/, ah PIP?,
and a b pi R^. The relation of these plant colors to aleurone color and
to a pericarp color known as cherry, present in these families, affords an
opportunity of checking some of these hypothetical formulae. Cherry
pericarp is a bright reddish purple, somewhat variable in intensity. In
the parent of one of these F2 progenies it was sufficiently light to make
possible the determination of the underlying aleurone color. The F2 seeds
consisted of colored and colorless aleurone in the ratio 140:171, a devia-
tion from a 27:37 ratio of 9.0 ± 5.9, or such a deviation as might occur
by chance three times in ten trials, P equaling 0.30. The Fi plants were
known to be AaRr, and in order to give a 27:37 ratio with respect
to aleurone color they must have been also C c. Cherry pericarp is of
such a nature that it never develops except in the presence of PI. With A
and PI it is cherry, but with a and PI it is brownish. It had been regarded
by the writer as due to a factor, Ch, but recently Dr. E. G. Anderson has
shown (by unpublished data) that the writer's Ch is apparently another
allelomorph of R, and at present it is known to exist only in the form /^.
Since all dilute purples of the lots under consideration here are assumed
to be A 6 PI f^, they should all have cherry pericarp. Again, since dilute
sun reds are pi pl, they should all have colorless pericarp. Furthermore,
since all green plants from colored seeds are supposed to be R^ R^, their
pericarp should likewise be colorless. Finally, since the colorless seeds
may lack color because of either a a, r r, or c c alone, or because of both
a a and r r, some green plants from colorless seeds should have color-
less pericarp, a R^ or A c R", and some should have brownish pericarp,
a PI /^. Of course all green plants with pl pl also must have colorless
pericarp.

The observed results are whoUy in accord with these suppositions. In
one F2 progeny, pericarp color was determined for all except a few plants.
From seeds with colored aleurone, all the dilute purples had cherry peri-
carp and all the dilute sun reds and greens had colorless pericarp. These
three classes of plant and pericarp color showed frequencies deviating from
the theoretical 27:9:18 relation by quantities such as might occur by
chance almost once in four trials, P equaling 0.23. From seeds with
colorless aleurone, all dilute purples had cherry pericarp, all dilute sun

108 R. A. Emerson

reds had colorless pericarp, and greens had in part brownish and in part
colorless pericarp. The deviations from the expected 27 : 9 : 18 : 20 relation
of these four color classes were such as might occur thru errors of random
sampling in more than seven out of any ten such trials, P equaling 0.72.
The comparisons follow:

Plant color

Dilute
purple

Dilute
sun red

Green

Green

Total

Pericarp color

Cherry

Colorless

Brownish

Colorless

Ilia

IVa

VIb

Illg, IVg, Vic

Colored aleurone:

Observed. . . .

43

10

0

35

88

Calculated . . .

44

15

0

29

88

Difference.-. .

—1

—5

0

+6

0

Colorless aleurone:

Observed. . . .

38

11

32

28

109

Calculated . . .

40

13

27

29

109

Difference . . .

—2

—2

+5

—1

0

Further tests of the factorial composition, with respect to PI, of some
F2 green plants of this cross are afforded by crosses between them and sun
red and dilute sun red plants. One F2 green crossed with sun red gave
27 purple plants (table 49, group 2). Since the green parent plant came
from a colored seed, it is assumed to have been PI PI R^ BF plus A A ov
A a. Two other greens crossed with dilute sun red gave 39 dilute purple
plants, and were therefore PI PI (group 2, table 49). Since one of these
green plants had brownish and the other had colorless pericarp, they are
assumed to have been also f^ and R' W, respectively. A fourth F2
green crossed with sun red gave purple and sun red plants, and a fifth
green crossed with dilute sun red gave dilute purple and dilute sun red
plants, indicating Plyl (group 3, table 49). The first of these two had
brownish and the second had colorless pericarp. They must therefore
have been r'^'' and I^ W, respectively. A sixth F2 green crossed with
dilute sun red gave only dilute sun red plants, and so must have been
yl'pl (group 4).

Plant Colors in Maize 109

Green Illg x green Via. — In the soctioiis immodiatoly preceding this,
it has been shown that intercrosses of greens may give dilute sun reds
(page 104), dikite purples (page 106), or sun reds (page 105) in Fi, the
particular color type depending on the genotypes of the greens chosen
for crossing. It remains to be shown that purple la can be produced ])y
intercrosses of gre'ens. A cross of green Via, aBplY, with green Illg,
Ah PI R\ should give this result, Fi being AaBb PlplR' /. Such
a cross has been made, with results as expected.

A stock of green plants was isolated from a cross of brown V, a B PI /,
with green VIc, a h pi /, and was shown, by crosses with aleurone testers
and with dilute sun red IVa, to be type Via, a B pi /. Another lot of
greens arose from a cross of purple Ig with green IVg. The purple Ig
parent was. from a lot consisting of purple la, purple Ig, dilute purple
Ilia, and green Illg, coming from a cross of purple Ig with dilute purple
Ilia heterozygous for R^ /. It was therefore AABhPlPlR^ W.
The green IVg plant with which it was crossed was known to be A 6 pi RF.
The Fi of this cross consisted, as was expected, of purples and greens only.
The purples were type Ig and must have been heterozygous for B b and
PI pi, and the greens must have been type Illg and heterozygous for
PI pl, or A Abb PI pi R^ RF. Two of these Fi greens were crossed with
one of the greens of tj^pe Via mentioned above. The two crosses, 9659
and 9660, resulted as expected in purple-anthered purples, type la, and
pink-anthered sun reds, type Ila, in the relation 18:20. It has been
demonstrated, therefore, that by crossing wholly green plants of appro-
priate genotypes it is possible to produce purple-anthered purples, the
most highly colored type known, a type that is dominant to all other
types.

Green Illg x purple la. — A green plant with homozygous purple aleurone
and belonging to a family (table 39, group 4) consisting of green-anthered
purples and greens only, and therefore theoretically being A b PI R^,
was crossed with a purple-anthered purple, A B PI /. A purple-anthered
purple Fi, A A Bb PI PI f R", 5350-9, was backcrossed with green IVg
of the genotype A b pl ?■", with the result that in the next generation
there appeared four color types, purple-anthered purple, green-anthered
purple, dilute purple, and green, in the relation 28:22:21:29. The
deviations from the expected equal distribution of the 100 individuals
were such as might occur by chance in considerably more than half of

110 R. A. Emerson

such trials, P equaling 0.57. It will be recalled that results like these
were obtained from a cross of green-anthered purple with dilute purple
(page 96), and of course the same results were to be expected since the Fi
in both cases is supposed to have been A A B b PI PI /R^.

The cross now under consideration has interest from the standpoint of
the relation of aleurone color to plant color, and also for certain hnkage
relations. The Fi was known to be, with respect to aleurone color,
A A Rr. Whether it was C C or C c was not known, since a strong red
pericarp made aleurone counts impracticable. The green plant on which
the Fi was backcrossed, was determined by appropriate tests to be C C,
so that the relation of the Fi purple to C is immaterial. The backcross
resulted in approximatelj'- equal numbers of seeds with and without
aleurone color, there being 109 colored and 110 colorless seeds. The
colorless seeds must have been A B C PI/ t^ and Ah C PI/ 7^, and
should therefore have produced purple-anthered purples and dilute purples
only; while the colored seeds must have been A B C PI R" / and Ah C
PI R^ r^, and should correspondingly have produced green-anthered
purples and greens only. The results were quite in accord with expecta-
tion, as is shown in the following comparison:

Green Total

Illg

29 51

0 49

It has been shown earlier in this paper (page 63) that a linkage exists
between the factor pair B h and a factor pair, Lg Ig, for normal or ligule-
less leaf, the percentage of crossing-over being about 30. It happens
that the Fi of this cross was Lg lg as well as B h, B lg having come from
one parent and h Lg from the other, and that the green plant used in the
backcross was h lg. There is no question here that the purple-anthered
purples and dilute purples produced from colorless seeds differed with
respect to the B h pair only. Their linkage with liguleless leaf, as indi-
cated by the percentage of crossing-over, was 29.4, or a deviation from
30 of 0.6 ± 2.0. Practically the same linkage relation was found for the
plants from colored seeds, green-anthered purples and greens. In this
case the percentage of crossing-over was 27.5, a deviation from 30 of

Color types

Purple,
purple anthers

Purple,
green anthers

Dilute
purple

la

lg

Ilia

Colored seeds. . . .

0

22

0

Colorless seeds . . .

28

0

21

Plant Colors in Maize 111

2.5 ±2.1, or such as might occur by chance about twice in five trials,
P equahng 0.42. It is to be assumed, therefore, that the same difference
exists between green-anthered purples and greens as between purple-
anthered purples and dilute purples, namely, a difference with respect
to the factor pair B b. This in turn is merely additional evidence that
plants which in the presence of / are dilute purples, A b PI, appear as
greens in the presence of R" r", which is the hypothesis under test thruout
this section of the paper.

Purple la x green-anthered dilute sun red

A purple-anthered purple, known from appropriate aleurone-color
tests to he R R and hence A B PI R^, was crossed with a dilute sun red
which differed from most dilute sun reds in showing much less anthocyanic
pigment, particularly in early stages of growth, than is usual in plants of
that type, and in having little, if any, color in its anthers. The F/s,
2975, were purple-anthered purples. F2 was expected to show the four
color types, purple, sun red, dilute purple, and dilute sun red, commonly
found in crosses of purple la with dilute sun red IVa. As a matter of
fact, the single F2 progeny grown was found to consist of these four color
types as major classes, but each class was found to have colored-anthered
(purple or pink) and green-anthered subclasses. The difference between
the two subclasses for purple and sun red was sharp, just as is the case
in crosses of purple la with green IVg, but it was often difficult to separate
green-anthered dilute purples from green-anthered dilute sun reds.
Ordinarily, anther color (purple or pink) is the surest means of distinguish-
ing between dilute purple and dilute sun red. When both have green
anthers the separation must be based on the relative amount of pigment
in other plant parts — a difference that is usually not very marked until
late in the life of the plants, when dilute purples usually show materially
more pigment, especially in parts not exposed to the sun, than do dilute
sun reds. It will be recalled that in crosses of purple la with green IVg,
both colored and green-anthered purples and sun reds appear, but that
all the dilute purples and dilute sun reds have colored anthers, the green-
anthered individuals appearing as wholly green in all plant parts except
perhaps the pericarp. But in the cross here considered, no wholly green
plants were found.

112

R. A. Emerson

The natural supposition is that there is here concerned still another
form of the R factor, such that, while it does not allow color to develop
in the anthers, does nevertheless result in the development of some antho-
cyanic pigment in other parts of the plant. The dilute sun red plant used
as one parent of this cross was found to he A c R with respect to alcurone.
The factor particularly concerned in the behavior here reported is there-
fore assigned the designation R''^. The Fi plants are accordingly assumed
to have been A A Bb Plpl R'' R^^. The frequency distribution for the
eight color types observed in F2 approached the theoretical distribution
so closely that deviations of the magnitude observed might occur by chance
nearly three times in any ten such trials, P equaling 0.72. The com-
parison follows:

x~\:i.,4-« T^cii,*-^ T^,*i,,+« T^;i,,4-«

Total

491
491

Plant color
Anther color

Purple
Purple

Purple
Green

Sun red
Pink

Sun red
Green

Dilute
purple
Purple

Dilute
purple
Green

Dilute

sun red

Pink

Dilute
sun red
Green

Observed. . .
Calculated .

212
207

77
69

66
69

22
23

60
09

23
23

22
23

3

8

Difference. . +5

+8 —3 —1 —3

0

0

One F2, a green-anthered purple, was tested in F3. This plant bred
true, producing 128 green-anthered purples and no other types.

It is unfortunate that the relation of aleurone color to plant color in
this cross afforded no check on the assumption that the observed behavior
with respect to anther color of dilute purples and reds was due to a factor
belonging to the allelomorphic series R^, R^, /, r^. True, the Fi plant
tested was heterozygous with respect to aleurone color, but this was
known to be due to C c. Since no further tests have been made, the only
evidence in support of the assumption of a factor R^^ is the very close
fit of observed with theoretical frequency distributions, the fact that colored
and green anthers in purple and sun red types of many other crosses have
been found to be due to the R factor, and the demonstrated presence of
R in the green-anthered sun red plant used in the cross.

,0 jch

Summary of results involving the allelomorphic series R^, R^, R^^, 1,1,1

Crosses of brown with green of type IVg have been shown to result
in purple Fi's, and in eight color types in F2 in a numerical relation approxi-
mating 81:27:27:9:27:9:36:40, or in six major color types, anther color
being disregarded, in approximately the relation 108:36:27:9:36:40.

Plant Colors in Maize 113

It has been noted that these results are wholly unhke those for crosses of
brown with green reported in an earher section of this paper, and are
similar in general, tho with marked differences in detail, to previously
discussed crosses of brown with dilute sun red. As an interpretation of
these results, it has been assumed that, in addition to the three pairs
A a, B b, PI 2)1, a fourth pair — members of a multiple-allelomorph
series, such as R^ Bf, / R", or R^ i^ — is concerned. It has been assumed
further that R^ or / is necessary ordinarily for the development of dilute
purple and dilute sun red and for the appearance of purple and pink
anthers in purples and sun reds, respectively, while /i" R° or r'' r^ is
necessary for green anthers of purples and sun reds and for the con-
version of dilute purples and dilute sun reds into wholly green plants.
Smiilarly, the appearance of green-anthered dilute purples and dilute
sun reds in a single cross has been ascribed to R^^ R^^. The relation of
the R allelomorph to both aleurone color and plant color has afforded
rehable tests of the hypothesis. Other tests have consisted of the
behavior in later generations of the several F2 color types and the results
of intercrosses between these types. Neither of these tests has been carried
to the point of exhausting all the possibilities, but in all a considerable
number of tests have been made and all have given results in support of
the hypothesis. A single linkage test, involving the B b pair with leaf
type, Lg Ig, has afforded added support. On the whole, therefore, the
hypothesis haS been, if not substantiated, at least rendered highly probable.

RELATION OF ALEURONE FACTORS C C AND Pr pr TO PLANT COLOR

The relations of the aleurone factors A and R to plant color have been
noted repeatedly in this account. A single observation suggests a rela-
tion between the aleurone-f actor pair C c and leaf color. Culture 2909
came from colored seeds of a selfed ear showing a 3 : 1 ratio of colored to
white seeds, and therefore heterozygous for a single pair of aleurone-color
factors. Several ears in the resulting progeny also gave 3 : 1 ratios. Tests
of four plants with aleurone testers gave conclusive evidence that the
C c pair was the one concerned. One selfed plant of the lot, 2909-32,
had 318 colored and 105 white seeds. Both the colored and the white
seeds produced only sun red plants, some with green and some with pink
anthers, indicating the genotype A A B BC cplpl W R^. All the plants
showed strong sun red pigment in the sheaths and the outer husks, but

114 R. A. Emerson

there was distinctly more red color in the leaves of the plants from colored
seeds than in the leaves of the plants from white seeds. Particular atten-
tion has not been given to a possible effect of the C factor on mature plant
colors of other color types. Many cultures of dilute sun reds and greens
have afforded opportunities for observing any effect of C and c on red color
in the leaves of seedlings, but no effects have been noted. No particular
attention was paid to the matter at the time when the seedlings were under
observation, but if the C c pair had exerted any marked influence it would
probably have been noted.

Numerous cultures of dilute sun red seedlings have been noted with
respect to possible effects of the aleurone-factor pair Pr pr, but no effect
has been observed, the purple and the red seeds having produced seedlings
with apparently the same intensity of red color. Likewise, no influence of
Pr pr on mature plant color has ever been observed in the case of either
sun red or dilute sun red. With purple and dilute purple plants, however,
a distinct effect is noticeable. Purple and dilute purple plants from seeds
with purple aleurone have purple anthers, while those from seeds witJi
red aleurone have reddish purple anthers (Plate I, 1 and 3, and Plate
II, 1 and 3). A similar effect is often seen also in the color of the inner
husks. In neither the anthers nor the husks is the effect always suffi-
ciently distinct to make possible an accurate separation of plants from
purple and from red seeds if they are growing in mixed cultures. In
some cases, however, the difference is very distinct. And when the
seeds are separated with respect to purple and red aleurone, the two lo+s
of plants resulting usually show fairly distinct differences in anther color
and often in husk color as well.

EXPRESSION OF PLANT-COLOR AND ALEURONE- COLOR FACTORS

The mode of expression of the several plant-color factors has been dis-
cussed in detail in this paper, and similar discussions of aleurone-color
factors are available in numerous other papers. Since aleurone colors
and certain plant colors — the purple-red series — are doubtless antho-
cyanins, it seems natural to expect close interrelations between them.
Many such relations have been noted in this account. There are certain
matters, however, which need to be brought together in a summary
discussion.

Plant Colors in Maize 115

It will be recalled (Emerson, 1918) that for the development of any
aleurone color, the presence of three dominant factors, A, C, and R,
and also of a duplex recessive factor pair, i i, is necessary. The Pr pr
pair has no visible expression except when associated with this combination
of the other factors, and then it determines whether the color shall be
purple or red. So far as is now known, the plant-color situation with
respect to complementary factors is not quite so complex. Something of
the same sort is seen, however, in the fact that no anthocyanic pigment
ordinarily develops except either in the presence of A and R"", /, or r"'',
or in the presence of A, B, and R^ R^ or r^ /. With the first of these
combinations, the pairs B h and PI pi determine the particular color
type of the purple-red series. Two of these types, purple and dilute
purple, are modified further by Pr pr, and the intensity of their color
depends also on the member of the R series present, r'^'^ exerting a more
pronounced effect than R'' or /. One type at least, sun red, is influenced
somewhat by C c. With the second combination. A, B, and R^ R'' or
r^ r", the pair PI pi determines whether the type shall be purple or sun
red. For the formation of the non-anthocyanic (flavonol) pigment, brown,
the interaction of a a with" either B or PI is essential, and usually very
little color develops except when both B and PI are present. Brown is
made more intense by the presence of /*.

Of the factors concerned with plant colors of maize, the A a pair is
one of the most fundamental, since it differentiates sharply the antho-
cyanins of the purple-red series, A B PI, A B pi, Ah PI, A b pi, from
the non-anthocyanic brown, aBPl, and the slightly brown or green
a B pi and ab PI and the wholly green a b pi. Without A no anthocyanin
shows in either the aleurone or the other parts of the plant. A second
fundamental pair is Pi pi, which differentiates the sun colors from those
that develop in local darkness. Purple (A B PI), dilute purple (A b Pi),
and brown (a B PI) are all able to .develop in darkness; while sun red
(ABpl), dilute sun red (Abpl), and the slight brown sometimes seen
in a B pi, do not develop except in the presence of light. Whether or not
the slight brown sometimes present in a 6 Pi forms in darkness has not
been determined. To the Pr pr pair is due a definite qualitative difference
in the colors formed which is presumably associated with a difference in
chemical composition of the pigments. In the presence of Pr aleurone
color is purple, and with pr it is red, and a similar difference, tho not always

116 R. A. Emerson

so sharp a one, is seen in the effects of Pr pr on the anther and husk color
of purples and dilute purples. The factors R^ and r^ on the one hand,
both recessive with respect to plant color, and R^ and / on the other
hand, both dominant for plant color, apparently alwaj'S differentiate
between colored and colorless anthers and silks in the purple-red series
of plant colors, and, when B is absent, determine whether or not antho-
cy.anin forms in any part of tlie plant. The pair B h influences mainly the
intensity of pigmentation. Thus, purple, A B PI, is more strongly
colored than is weak purple, A B^ PI, which in turn is more strongly
colored than is dilute purple, A b PL The same relation holds between
sun red, A B pi, weak sun red, A B^ pi, and dilute sun red, A b pi. Brown
color shows very little in ab PI but is strongly developed in a 5 PL
A similar difference, however, exists between the slight brown of a B pl
and the full brown oi a B PL In the one case in which an effect of C c
has been noted, C acted as an intensifier of color.

There are som.ewhat marked differences between the several factor
pairs with respect to the stage of plant development at which their influence
is expressed. Seedlings of purple, sun red, dilute purple, and dilute sun
red normally exhibit no characteristic differences in intensity or extent
of pigmentation. The B b and PI pl pairs, which differentiate these
color types so sharply at a later stage of growth, do not, therefore, come
into expression early. All of these types are more highly colored late
in their growth period than they are as seedlings, but the later changes
are much more pronounced, for instance, in dilute purple than in dilute
sun red, and somewhat more so in purple than in sun red. Apparently,
Pl exerts its influence comparatively late, but under the intensifying
influence of B, even Pl expresses itself fairly early.

The several factor pairs differ more or less with respect to the particular
plant parts affected. Differences in the expression of B, B^, and b are
more apparent in the husks and the sheaths, particularly the upper sheaths,
than elsewhere. When plants of the genotype a B pl, common^ classed
as green, show any brown, the color is limited to the sheaths and the
outer husks. The difference between purple (A B Pl) and sun red {A B pl)
on the one hand, and dilute purple (A b Pl) and dilute sun red (A b pl)
on the other, is more pronounced in the husks and the sheaths than
elsewhere. Little difference is apparent between the two groups with
respect to the color of anthers, glumes, silks, and the like. The pair

Plant Colors in Maize 117

PI pi is perhaps expressed most definitely in the color of anthers, tho
the expression is by no means limited to them. Puiple {A B PI) and
dilute purple {A b PI) differ from sun red (A B pJ) and dilute sun red
(A hpl), not merely in having purple rather than pink anthers, but also
in the coloration of their inner husks, their culms, and the like. What
little brown color is seen in ab PI is limited almost wholly to the staminate
inflorescence. The staminate inflorescence of purples, A B PI, and of
browns, a B PI, is strongly colored, but that of dilute purple, A b PI,
except for anther color, is not very different from what is seen in dilute
sun red, A b pi. The PI factor, when associated with r"^^, is expressed
in the pericarp as cherry in purple and in dilute purple, and as brownish
in brown and in green of the genotype a b PL

Factors B b and PI pi are not known to be concerned with aleurone
color. All the other factors affecting plant color are aleurone-color
factors also. Of these the pair Pr pr influences anther color of purple
and dilute purple, and to some degree the husk color as well. The pair
C c has been observed to affect the leaf color of mature plants of the
sun red type. The pair A a is expressed to some degree in all such parts
as culms, sheaths, husks, glumes, anthers, and silks. The pericarp,
if a pericarp factor P is present, is red with A and brown with a, or if r'^'^
and Pi are present, it is cherry with A and brownish with a. The R
series of factors influences many plant parts. With duplex R^ or r^,
no color develops in any part of the plant, except the aleurone, provided
B is absent. With B these factors give colorless anthers and silks merely.
Factors K^ and /, if A also is present, affect practically all plant parts
in which anthocyanic pigments ever develop, but are not iknown to
have any influence on the color of the pericarp. The factor r'^^ is, how-
ever, concerned with pericarp color provided PI also is present. This
factor has a marked influence on the amount of color that forms in the
leaves, particularly of dilute purple and dilute sun red.

It is of no little interest that the R series of factors, which behaves
as a group of multiple allelomorphs with regard to plant color, usually
acts as a simple pair in respect to aleurone color.* Moreover, some of
these factors act as dominants with respect to aleurone color and as
recessives with respect to plant color, while the dominance of others is

« There is'^some evidence that at least one aleurone-color pattern is dependent on an allelomorph of
R r, the three thus constituting a group of triple allelomorphs affecting aleurone-color development.

118 R. A. Emerson

the reverse of this. For example, r" and r"'' are recessive for aleurone
and dominant for plant color, and R^ is dominant for aleurone and
recessive for plant color, while R'^ is dominant and r^ recessive for both
alem-one and plant colors.

SUMMARY

In this account, six major plant-color types of maize, purple, sun red,
dilute purple, dilute sun red, brown, and green (colorless), together with
the subtj^pes, weak purple, weak sun red, green-anthered purple, green-
anthered sun red, and five genotypes of green, are described and illustrated,
and their environmental and genetic relations are discussed.

The sun red and dilute sun red types are shown to be dependent on
Hght for the development of their color, while the purple, dilute purple,
and brown types develop their characteristic colors in darkness.
Diversities of temperature and of soil moisture are shown to have no
direct effect on the formation of maize plant colors but to have an indirect
relation to them thru their influence on soil fertility, which in turn bears
a definite relation to the development of the purple-red series of plant
color, anrthocyanins, but little or no relation to brown. Sun colors
particularly are shown to be markedly intensified by infertile soil. It is
noted that the several types of the purple-red series are sharply
differentiated when grown on fertile soil, but that their characteristic
differences are largely masked by growth on infertile soil, while the
brown-green* series is most readily distinguished from the purple-red
series, especially in the seedling stage, if grown on infertile soil. It is
suggested that the effect of infertile soil may be due to a deficiency of
nitrogen, and perhaps of phosphorus. Observations indicating a close
connection between the accumulation of carbohydrates and strong colora-
tion are reported, and the inference that the effect of infertile soil is
brought about thru checking growth without inhibiting photosynthesis,
thus allowing an accumulation of carbohydrates, is discussed.

In an attempt at a genetic analysis of the several plant-color types,
data accumulated during a period of some ten years, and involving an
examination of approximately 680 progenies and not less than 48,000
individual plants, are reported. As an interpretation of the results
obtained from the more complex crosses, the allelomorphic pairs A a
and PI j)l, and the multiple allelomorphs B, B"", b\ h, and R\ R\ R'\

Plant Colors in Maize 119

/, r*, r*^, are assumed and genetic formulae are assigned to the several
color types as follows: purple, A B PI; sun red, A B pi; dilute purple,
Ab PI; dilute sun red, Abpl; brown, a B PI; green, a B j^, ah PI, ah pi;
all these having in addition R\ /, or r"^. The factor i^''" is assumed
to be the causal factor for green anthers and silks in purple, sun red,
dilute purple, and dilute sun red types, and W and r'' are assumed to have
the same effect on purple and sun red and to insure colorlessness (green
type) thruout in what would otherwise be dilute purple and dilute sun red,
the R series having no effect on brown, except for r'^'', which intensifies
brown as well as purple and dilute purple. Of the R scries, R^ is dominant
and 1^ is recessive for both plant and aleurone color, f and r'^^ are dominant
for plant and recessive for aleurone color, R^ is recessive for plant and
dominant for aleurone color, and R''^ is dominant for aleurone color and
also for plant color except of the anthers and the silks, for which it is
recessive. The A a pair is concerned with both aleurone and plant color,
and the aleurone pairs C c and Pr pr are assumed to exert a modifying
effect on certain plant colors.

The principal hypotheses involved are shown to be in keeping with
observed facts when subjected to practically all the available genetic
tests, such as backcrosses of Fi with multiple recessives, behavior of F2
types in later generations, intercrosses of the several F2 types, relation
of aleurone color to plant color, linkage of certain plant-color types with
normal- and liguleless-leaf types and of other plant-color types with
yellow and white endosperm. Approximately 32 per cent of crossing-
over is reported between B h and Lg Ig and about 20 to 30 per cent between
PI pi and Y y.

120 R. A. Emerson

LITERATURE CITED

Collins, G. N. Gametic coupling as a cause of correlations. Amer.
nat. 46:569-590. 1912.

CzARTKOwsKi, Adam. Authocyanbildung und Aschenbestandteile.
Deut. bot. Gesell. Ber. 32:407-410. 1914.

East, E. M., and Hayes, H. K. Inheritance in maize. Connecticut
Agr. Exp. Sta. Bui. 167: 1-142. 1911.

Emerson, R. A. Genetic correlation and spurious allelomorphism in maize.
Nebraska Agr. Exp. Sta. Ann. rept. 24:58-90. 1911.

The inheritance of the ligule and auricles of corn leaves.

Nebraska Agr. Exp. Sta. Ann. rept. 25:81-88. 1912.

A fifth pair of factors, A a, for aleurone color in maize, and its

relation to the C c and R r pairs. Cornell Univ. Agr. Exp. Sta.
Memoir 16:225-289. 1918.

Gernert, W. B. The analysis of characters in corn and their behavior
in transmission, p. 1-58. (Published by the author, Champaign,
Illinois.) 1912.

Knudson, Lewis. Influence of certain carbohvdrates on green plants.
Cornell Univ. Agr. Exp. Sta. Memou- 9:1-75. 1916.

LiNDSTROM, E. W. Chlorophyll inheritance in maize. Cornell Univ.
Agr. Exp. Sta. Memoir 13 : 1-68. 1918.

Sando, Charles E., and Bartlett, H. H. The occurrence of quercetin
in Emerson's brown-husked type of maize. Journ. agr. research. 1921.
(In press.)

Webber, Herbert J. Correlation of characters in plant breeding.
Amer. Breeders' Assoc. 2:73-83. 1908.

Wheldale, M. On the formation of anthocyanin. Journ. genetics
1:133-158. 1911.

Memoir .3^, A Modified Babcock Method for Determining Fat in Butter, the second preceding number in
this series of publications, was mailed on December 10, 1920.

Plant Colors in Maize

121

APPENDIX

TABLE 1. Fi Progenies of Purple la x Green VTc

Pedigree nos.

Number of

Pi

Fi

1 1 plants
(Purple la)

724-1 X 722-1

857

IS

1121-8x1122-7

1420, 1512, 2022.

40

1122-5 X 1121-2

1419, 1511. .

36

1525-5 X 1546-5

20.56

17

Total, 4 progenies

111

TABLE 2. F2 Progenies of Purple la x Green Vie

Pedigree nos.

Number of F2 plants

Group

Fi

Fo

Purple
la

Sun red
Ila

Dilute

purple

Ilia

Dilute

smi red

IVa

Brown
V

Green
Via, b, c

1

1419- 1..
1511- 1..
1512-12.
2022- 3..
2056- 6..

-11..
-16..

1513

2018

2020

4012,4013.
2415, 2416,

42.84

2417, 2418,
2553-2559,
4001-1007.
2412, 4066,

4067

94
61
54

7

39

96
17

22

19

16

6

13

22
3

26

13

23

6

17

24
11

12

4
7
3

4

3

1

20

13

21

4

16

26
8

23
9

7
1

10

8
7

Total, 7 progenies

36S

101

120

U

108

65

2

1514-24..

-31
2000- 8. .
2019-28.

-34..

2906- 1 . .

2907- 1 . .

- 7. ,

2981- 2.

- 5
4020- 7
4032- 1

- 3

- 4.

20.54

2055

2419,4065

4281

4282

5303

5290-5293.

7050, 7051
5299, 5300,

70.54, 7055
.50)6, 5067 .
5068, 5069
.5712,6810

.5739

50!^

5087

20
22
92
24
21
17

93

105
17

20
10<)
16
15
13

7
4
29
8
6
7

26

46
4
6

44
5
/
5

8
4
21
4
4
5

34

30
5
2

26
3
5
4

1
2

8
0

4
2

7

10
1
1

12
2

4
1

5
2

19
4

7
6

34

38
8
2

31
3
4
7

2
6
25
6
4
3

23

31
3
3

33
2
3
7

Total, 14 progenies ....

5^

204

155

57

170

151

Total, 21 progenies

952

305

275

91

278

216

122

R. A. Emerson

TABLE 3. F'' Progenies of Purple x Green Backcbossed with Geeen
(la X Vic) X Vic

Pedigree nos.

Number of F2 plants

Group

Fi X Vic

F2

Purple
la

Sun
red
Ila

Dilute

purple

Ilia

Dilute

sun red

IVa

Brown
V

Green
Via,
b, c

1

1420- 1x1430- 3
1511- 1x1516- 1.
1512-12 X -14.
2056-16x1995- 6.

1514

2019

2021

2413, 4068

12

18

23

4

19

8

18

10

15

12
16
8

16
8

10
6

14

18

13

8

45
50
44
18

Total 4 progenies

57

55

51

40

53

157

2

2867-69x4032- 1.

2906- 1x2887-10.

2907- Ix -22

- 7x4032-41.
4020- 7 X 2888-13 .
4032- 2 X 2921- 4 .

3x2888- 5.

3x2922-16.

4x2888- 1.

4x2921- 4.

5740

5305

5296,7052,

7053...

5301,5302

5714

5094

5086

5085

5089

5090-5092

7

7

10

16

2

8

19

14

5

25

4

5

11
16
9
6
16
10
15
13

6

2

10
16
9
IS
21
22
12
19

3

8

11
19
4
12
12
16
17
18

4
3

9
25

4
15
18

8
18
15

10
9

26
47
18
33
46
34
45
54

Total, 10 progenies

113

105

125

120

119

322

Total, 14 progenies

170

160

176

160

172

479

Plant Colors in Maize 123

TABLE 4. Fi Progenies of Dilute Sun Red IVa x Brown V

Pedigree nos.

Number of Fi plants

Group

Pi

Fi

Purple
la

Sun red
Ila

Dilute

purple

Ilia

Dilute

sun red

IVa

2025-23x2192-14..
2029- 8 X 1945-11 .

- 8x2013-19.

- 8x2014- 8..
2031-10x1945-10.

-32x2012- 1..
2948-16x4042- 2..
4253- 2x4299- 2..
4305- 5x4042- 2..

2333, 4314

25
30
17
5
16
20
79
46
24

2304, 3596

2311

2310,4034

2309

1

2392

5168, A108, A120....

5528, 6748A

5193, 5194

i

Total, 9 progenies ... . ....

262

I

2018-69x2192-18..
2030-13 X -14..
2031-20x2012- 1..

2043- 2x2026-17..
2049-14x2192-14..
2473- 3x2341- 1.
4370- 5 X 3000- 2 .

2386, 4301

30

7

55

15

24

4

8

35
6

55
18
21
2
10

4319

2

2325, 2326, 2543,
2544, 2950, 2951 . .
2347,4326

2336, 4327

4029

4746, 4747

Total, 7 progenies

143

147

2023-19x2192-12..

-23 X -12..
2027- 9 X -14.
2410- 4x2417- 2.

- 6x - 1.
5500- 5 X 5130- 1 . .

2332,4311

19
15
15
9
23
24

26
16
18
6
32
25

2330, 4310

2334, 4316

3

2993, 2994

2995-2998. .

A65

Total, 6 progenies

105

123

2025-10x2192-14..
2029-27x2012- 1..

-32 X - 1 . .

-34x2014- 8..

4315

1
4
3
1

2
3
5

1

6
5
6
2

3

2319,4055

4

2316,4318

3

2314, 4054

6

Total, 4 progenies

-

9

11

19

17

124

R. A. Emerson

TABLE 5. Fo Progenies of Dilute Sun Red IVa x Brown V

Pedigree no.3.

Number of F2 plants

Group

Fi

F2

Purple
la

Sun red
Ila

Dilute

purple

Ilia

Dilute

sun red

IVa

Brown
V

Green
Via,
b, c

1

2310- 2..
2332- 1 . .
2950- 1 . .

- 4..
-17..
-19..

2995- 7 . .

2996- 1 . .
4029- 2 . .
4034- 1 . .

- 2..

5193- 1 . .

5194- 5..
5528- 8..

4036, 4037 .
2999, 3000 .
5036,5037.
5030, 5031 .
5034,5035.
5032, 5033 .
5000-5007
5008, 5009 .

5095

5098,5099.

5104

A135

A136

6748B

15
31
36
37
32
39
75
150
61
46
42
20
10
49

7

9

12

15

5

12

24

50

23

12

20

5

3

11

6
8
12
13
14
10
20
58
11
19
17
4
12
14

3

1
2
3
6
3
5
20
5
7
8
3
1
4

3
15
10

8
13
12
21
48
22
17
13

4

4
12

7

7

9

13

9

5

17

45

11

7

21

1

7

18

Total, 14 progenies

643

208

218

71

202

177

2

2973- 5..

2974- 9..
4046- 3..
5173- 4..
S17-19...

5056-5062.
5063-5065.
5157,5158.

A128

7762

55
75
20
19
35

23
24
11
5
11

21

23
6
8
5

6

10

5

1

1

17

18

V

9

14

17

22

4

9

4

Total, 5 progenies . . . .

204

74

63

23

65

56

Total, 19 progenies ....

847

282

281

94

267

233

TABLE 6. F2 Progenies of Dilute Sun Red x Brown Backcrossed with Green

(IVa X V) X Vic

Pedigree nos.

Number of F2 plants

Fi X Vic

F2

Purple
la

Sun red
Ila

Dilute

purple

Ilia

Dilute

sun red

IVa

Brown
V

Green
Via,
b, c

2310- 1x2411-6..
2922-13x4029- 2..
4029- 2x2921-10..
4034- 1x2922-16..
- 2x2921-68..
5813-25x5528- 8..
A129-12xA108-6..

4035

5652,5653..

5096

5100-5103..

5105

6749

A243,A244.

3

22
9

10

12
3

25

4
13
18
13
5
0
19

3
19
12
17
5
2
20

6
24

8
11

4

4
15

2

27

13

9

4

1

23

17
75
51
33
16
9
48

To al, 7 progenies . . . .

84

72

78

72

79

249

Plant Colors in Maize

125

TABLE 7. Fj Progenies of Purple x Green and Dilute Sun Red x Brown Back-
crossed WITH Dilute Sun Red

(la X Vic) X IVa, and (IVa x V) x

IVa

Pedigree nos.

Number of Fa plants

Group

Fi X IVa

F2

Purple
la

Sun red
Ila

Dilute

purple

Ilia

Dilute

sun red

IVa

1

2050-16 X 1992-13

2889-54 X 4032- 1

2414, 4069, 4070. . .
5741-5744

18
24

16

27

21
21

15
24

Total, 2 progenies

42

43

42

39

2

6730 - 9 X 6748A- 5 . ,
6748A-16 X 6751 -22..

-18 X -22..

-19 X - 1 . .

-20 X - 1 . .
A121- Ox A108- 8..

L188- 1 x5528 - 8..

7467,7828

7229

7230

7231

7232

A241, A242, A401,

A462

6786, S2

87
40
28
40
30

28
4

79
32

28
33
25

25
5

75
42
26
30
32

38
3

71
41
35
36
20

45
4

Total, 7 progenies

257

227

246

252

Total, 9 progenies

299

270

288

291

TABLE 8.

Fs Progenies of Selfed and Back crossed Fo Purple Plants of the Crosses
Purple la x Green Vie and Dilute Sun Red IVa x Brown V

Pedigree

nos.

Number of F3

plants

Group

F2

F3

Purple
la

Sun red
Ila

Dilute

purple

Ilia

Dilute

sun red

IVa

Brown
V

Green

1513-41

2015, 400S,
1009

204S, 2475,
4010,4011

4208

4271

4275

5210

5213

5214

32

01
15
13
10

9
25
22

14

14

7
8
8
3
7
5

8

21
5
6
6
3

(;
5

3

7
0
1
2

0

0

1

6

18
6
3
7
1
4

12

(VIa,b,c)
8

-68

1

2018- 2

- 9

10
4
3

2020- 1

3

40O5- 6

1

-62

-63

1
4

Total, 8 progenies

193

66

60

16

57

34

2020-117x2043-11

4279

4

4

11

4

4

18

126

R, A. Emerson

TABLE 8 (continued)

Pedigree nos.

Number of F3 plants

Group

F2

F3

Purple
la

Sun red
lla

Dilute

purple

Ilia

Dilute

sun red

IVa

Brown
V

1
Green

2

1513 - 35

-138

2018 - 6

4066 - 3

6748B- 41

2046

2052

4270

5216,5217.
7400

11
16
25
38
12

4
6
9
14
3

6
1
5.
13
4

1
2
5
5
0

Total, 5 progenies

102

36

29

13

1513- 59

- 92

-133

4037- 5

2047

2053

2049

5136,5137.

20
24
16
35

6

6

4

15

5
3
9
6

(Via)
3
3
2

7

3

Total, 4 progenies

95

31

23

15

2020-46 X 2200- 8
2411- 4x2412- 2
2443- 2x - 2
2922-12x4037- 5

4283

2981-2983.
2984-2986.
5138-5140.

5

8

7

34

1

6

8

43

3

2

7

32

3
10

4
36

Total, 4 progenies

54

58

44

53

2018-27

4280

4276

4277

5079

5010-5013.

5218

A78

19
19
29
11
195
29
16

5
3

7
4

77

12

6

9
9
6
4
71
6
6

(Vib)
1

2020-15

-30

3

4

4001-12

1

4

4005- 5

4066- 5

5099-22

29
3

1

Total, 7 progenies

318

114

111

42

(;

1513- 2

-110

2018- 92

-119

2412- 1

2050

2051

4273

4269

4033

19
16
31
33
40

3
6

13
9

13

Total, 5 progenies .

139

44

Plant Colors in Maize

TABLE S (concluded)

127

Pedigree nos.

Number of F3 plants

Group

F,

Fa

Purple
la

Suji red
Ila

Dilute

purple

Ilia

Dilute

sun red

IVa

Brown
V

Green

5
(con-
tin-
ued)

2411-5x2412-1 .
24^-1 X -1 .

4032

4019,4020

4
8

I

S

Tot^l, 2 progenies

12

9

6

4006- I

4065-14

5014,5015.
5209

126

42

37
12

Total, 2 progenies

168

49

TABLE 9. F4 Progenies of Self-pollinated Purple Plants of F3 Lots Consisting
OF Color Types la, Ilia, V. and VIb

Pedigree nos.

Number of F4 plants

Group

F3

F4

Purple
la

Dilute

purple

Ilia

Brown

V -

Green
VIb

5010- 7

- 9

7020, 7021

7022 7023

51
53

46
35

15
19
17
17

12
22
26
14

8
6

1

-11

5011- 4

7024, 7025

5

7028. 7029

1

Total, 4 progenies .

185

68

74

20

4276-32

5010- 2

5011- 6

5181, A170

46
14

28

12

2

14

2

7092

7091,6837

Total, 3 progenies.

8<S

28

3

5011-2

7026, 7027

67

21

128

R. A. Emerson

TABLE 10. F3 Progenies of F2 Sun Red Plants of the Crosses Purple la x Green
Vic AND Dilute Sun Red IVa x Brown V

Pedigree nos.

Number of F3 plants

Group

F2

F3

Sun red
Ila

Dilute

sun red

IVa

Green

1513-152

2038,2474,4292

4286

38
19
30
9
30

11

7
12

4

8

(Via, c)
11

2018- 4

*16

- 39

4287

11

- 44

4288

6

- 56

4289

11

1

Total, 5 progenies

126

42

55

1513-100x1516-20....
2018- 56x2043-11....
2020-118 X -11....

2039, 4293

7
3
4

8
1
9

t23

4290

7

4291

20

Total, 3 progenies

14

18

50

2

4037-2

5126, 5127

23

9

3

4037-24x2921-15

5128, 5129, 7074

50

(Via)
43

* Plus one brown V plant,
t Plus one purple la plant.

Plant Colors in Maize

129

TABLE 11. F3 Progenies of F. Dilute Purple Plants of the Crosses Purple la
X Green Vie and Dilute Sun Red IVa x Brown V

Pedigree nos.

Number of F3 plants

Group

F2

F3

Dilute

purple

Ilia

Dilute

sun red

IVa

Green

2018-18

4037- 9

5099- 7

A120-13

4296

14
38
35

8

6

9

15

1

(VIb, c)
12

5117,5118

16

A77

19

1

A229

3

Total, 4 progenies

95

31

50

2922-16x4037-9

5119-5121

21

25

57

2

4066-9

5219

57

21

3

4037-14

5095-29

5290-12

5122,5123

A63

16

9

60

(VIb)
5
1

7056,7057

14

Total, 3 progenies

85

20

4

4065-50 1

5212

21

TABLE 12. F3 Progenies of Fi Dilute Sun Red Plants of the Crosses Purple la x
Green Vie and Dilute Sun Red IVa x Brown V

Pedigree nos.

Number of F3 plants

Group

F,

Fa

Dilute

sun red

IVa

Green
Vic

4036-9

6750-4

A120-8

5115

16
12

6

7247, 7399

8

1

A228

3

Total, 3 progenies

62

17

4036-8

4042-2

5116

27
65

5166

2

Total, 2 progenies

92

2922-18x4042-2

5169-5171

69

130

R. A. Emerson

TABLE 13. F3 Progenies of F2 Brown Plants of the Crosses Purple la x Green Vie
AND Dilute Sun Red IVa x Brown V

Pedigree nos.

Number of F3 plants

Group

F2

F3

Brown
V

Green

1513-12

2025,4313

33
16
23
16

8

(Via, b, c)
35

2020- 8

4309

13

-47

4305

*n

1

-98

4307

8

4065-12

5211

7

Total 5 progenies

96

74

1513- 16

2030

21
23
30
32
94
64
29
46
15

(Via, b)
6

- 39

2026

10

-143

2027

9

-194

2023

9

2018- 69

2539,2540,4299,4300
2338,4302

25

- 96

20

2

2020- 57

4306

9

4037- 6

5130,7076

12

6748B-37 . .

7401

4

Total, 9 progenies ...

354

104

4037-6x2922-6

5131-5133

34

41

* Plus one sun red Ila plant.

Plant Colors in Maize

131

TABLE 14. Progenies of F2 and F3 Brown Plants, of the Crosses Purple la x
Green Vie and Dilute Sun Red IVa x Brown V, Crossed with Dilute Sun Red
IVa Plants

Pedigree nos.

Number of F3 plants

Group

F. X IVa

F3

Purple
la

Sun red
Ila

Dilute

purple

Ilia

Dilute

sun red

IVa

1

2018-69 X 2192-18. .
4370- 5 X 3000- 2. .

2386, 4301

4746,4747

30

8

35
10

Total, 2 progenies

38

45

2410-4 X 2417-2. . . .
-6 X -1. . . .

2993, 2994

9
23

6
32

2995-2998

2

Total, 2 progenies

32

38

3

5095-20 X L170-1 . .

S17

15

F3 X IVa

F4

Number of F4 plants

4

2025-10 X 2192-14. .

4315

1

2

6

3

2030-13 X 2192-14. .
20i3- 2 X 2026-17. .

4319

7
15

6
18

5

2347,4326

Total , 2 progenies

22

24

2023-19x2192-12..

-23 X -12. .

2027- 9 X -14. .

5500- 5 x5130- 1..

2332, 4311

19
15
15
24

26
16
18
25

2330,4310

2334, 4316

6

A65

Total, 4 progenies. . .

73

85

7

2025-23 X 2192-14. .
4253- 2 X 4299- 2. .
4305- 5 X 4042- 2. .

.2333,4314

5528, 6748A

.5193,5194

25

*46

24

Total, 3 progenies

95

* Plus one dilute sun red IVa plant.

132

R. A. Emerson

TABLE 15. Fs Progenies of Selfed axd Backcrossed Green Plants of the Crosses
Purple la x Green Vie and Dilute Sun Red IVa x Brown V

Group

Pedigree

Xos.

Number of
F3 plants

F2

F3

(Green)

1513 - 42

2033

(VI)
22

-106

2036

18

-Ill

2032

13

4036 - 6

5114

22

4037 - 29

4066 - 4

5095 - 30

674SB- 11

5124,5125

42

1

5215

32

A62

8

7402. ....

22

Total, 8 progenies

179

1514- 9

2034

20

-37

2035

19

-47

2037

18

2

6749- 1

7242

19

- 4

7243.. . . .

20

Total, 5 progenies

96

2019- 40

2364, 4356

(Via)
*26

- 63

2356, 43^^

24

- 92

23S4

10

3

- 98

2374

10

-106 J

2357

15

Total, 5 progenies

85

2019-33

2^9, 43o4

(Vlb)
29

—0/

2373, 4353

34

4

-73

2379

10

-84

2383

14

Total, 4 progenies

87

2019-17

-25

2395

(Vic)
14

,.

2^48,4357

29

Total, 2 progenies

43

* Plus one brown V pUint.

Plant Colors in Maize

133

TABLE 16. Fi Progenies of Crosses of Green Via, VIb, and VTc with Dilute Sun

Red IVa 5^

Pedigref

' nos.

Number of Fi plants

Group

Pi

Fi

Sun red
Ila

Dilute

purple

Ilia

Dilute

sun red

IVa

2047-25x2192-14

2049-12 X -14

4300-14 X 4364- 1

4307- 9x4042- 2

2392

16
20
52
60

2393

1

5198

5183,5184

Total, 4 progenies

148

2036-9 X 2192 14

4725-2x5095-30

4320

9
67

A96, A97

2

Total, 2 progenies

76

3

2025-12x2192-14

2335

24

2019- 29x1946- 4....

- 40x2192-18....
-63x -18....

- 92x1945-10....
-98x -10....
-104 X 2012- 1 . . . .
-103x2192-18....

2398, 2399

30
5
11
13
11
13
27

19

2365, 4340

5

2358, 4349

10

2385

12

4

2375

12

2363

12

2359, 4351

15

Total, 7 Droeenies

110

85

2019-33x2192-18

-51 X194&- 4

-57x2192-18

-73x1945-11

-84 X -10

2352, 4342

5

19

8

2

22

4

2361,4347

15

5

2369,2370,4345

2377, 2378

14
6

2382,4352

26

Total, 5 progenies

56

65

2019-17x194^11

-19 X -11

-25 X -11

2396, 2397

43

2381

19

2351,4344

44

6

Total, 3 progenies

106

134

R. A. Emerson

TABLE 17. F2 AND Backcross Progenies of Dilute Sun Red IVa x Green Vie

Pedigree nos.

Number of Fo plants

Group

Fi

F2

Dilute

sun red

IVa

Green
Vic

1983-34

4502, 4503

27

199

43

11

285-^ 7

4677-4679

73

1

2866- 1

6471, 6472

15

Total, 3 progenies

269

99

Fi X Vic
2854-13 X 2887-69

6325, 6326

87
42
93
90
45

96

-16 X -69

2861- Ix -41

2866- 2x2888- 2

4707-82x4685- 1

6319-6321

45

4686-4688

100

2

5748-5750, 6485-6487
6533-6535

74
43

Total 5 progenies

357

358

TABLE

18. Fi Progenies of Intercrosses

BETWEEN Green Plants, Via, VIb, and Vie

Pedigree nos.

Number of Fi plants

Group

Pi

Fi

Brown
V

Green
VI

1

2019-25x2019-106

2354

23

2

2019-25x2019-33

2350, 4343

22

2019- 40 X 2019- 63

2367

25

- 98 x - 40

2376

25

3

-104 X -106

2362

22

Total, 3 progenies

72

4

2019-57x2019-51

2371,4346

24

2019- 33x2019-63

- 40 X -33

2355

6

8
14

7
5

19

2366, 4341

28

5

- 57 X -98

2372, 4350

26

-73x -40

-106 X -51

2380

16

2360

16

Total, 5 progenies

40

105

Plant Colors in Maize 135

TABLE 19. F2 Progenies of Crosses Between Brown V and Green Vie

Pedigree

nos.

Number of F2 plants

F,

F2

Brown
V

Green
Via, b, c

1514-12...

2029

19
22
25
40
15
21
46
14
53
24
38

16

-23. . .

2031

13

-38 :

2028

16

2983- 7...

5071, 5072

44

-11...

5070

11

2986- 4

5078

8

- 9...

5077

36

4035-35 ..

5110

6

4068- 4...

5225

23

-10

5227

20

-11 .

5226

30

Total,

1 1 progenies

317

223

TABLE 20. F3 Progenies from F2 Brown Plants of the Cross Brown V x Green

Vic

Pedigree nos.

Number of F3 plants

Group

F2

Fa

Brown
V

Green
VI

2031-28

4323

19
10

-32

2323

1

Total, 2 progenies

29

2031-20

2324, 2541, 2542,

2948, 2949

2327, 2328

82
18

2

-29

34
6

Total, 2 progenies

100

40

2029-27

2320, 4321

17
22

20

-34

2315, 4322

19

3

Total, 2 progenies. ...

39

39

136

R. A. Emerson

TABLE 21.

Fo Progenies of the Crosses Sun Red Ila x Green Vie and Dilute Sun
Red IVa x Green Via

Pedigree nos.

Number of Fa plants

Group

Fi

Fj

Sun red
Ila

Dilute

sun red

IVa

Green
Via, c

1514-32

2040, 4294

53
40
24
26
91
203
83
47
28
20
28
49
14
35
44
42

16
14
10

4
42
55
33
13

6

2
12
21

5
16

9
10

19

-76

2041, 4295

23

2083- 1

4336, 4337

11

- 2

4338, 4339

11

2981- 3

4992, 4993

45

- 4

4994-4996

84

4014r- 1

5554-5557

33

- 3

5559-5563

13

1

4019- 2

5691, 5692

18

- 4

5685, 5686

12

4020- 1

5708

10

4035- 3

5111-5113

24

4040- 2

5148,5149

13

6661- 9

7379

21

6662- 1 . .

7381

29

- 8

7380

17

Total, 16 progenies

827

268

383

2398- 2

4426,4427

5097

6951-6953

28
31
127
92
65

9
18
38
25
30

12

4029- 1

4776- 1

4780- 9

-11

21
71

2

6960, 6961

42

6954-6956

33

Total, 5 progenies

343

120

179

1416- 1x1430- 1

2888-22 x 4019- 2

2922-18x4014- 3

4014- 1x2922- 1

4019- 2x2888- 1

- 4x - 1

4020- 1 X 2887-69

1494, 2074

39
16
30

3
15
24

7

39
14
26
3
14
13
14

92

5694B, 5695A

5563-5565

22
68

5558

10

3

5697,5698

22

5689, 5690

31

5709

22

Total, 7 progenies

134

123

267

2921-15x4029- 1

4774- 1x4710-45

4781- 2 X 4707-35

4782- 5 X -18

-13 X -15

4789- 4 X -19

6661- 9x6690-17

6790- 5x6809-18

5654-5656

28
78
54
103
80
50
17
32

37
71
76
88
101
43
17
32

80

6945, 6946

151

6967, 6968

132

6972, 6973

195

4

6974-6978, 7667, 7668
6989, 6990

191
108

7328, 7329

38

7293

67

442

465

962

Plant Colors in Maize

137

TABLE 22. Fo Progenies of the Crosses Dilute Purple Ilia x Green Vie and
Dilute Sun Red IVa x Green Vib

Pedigree nos.

Number of Fn plants

Group

Fi

F2

Dilute

purple

Illa

Dilute

sun red

IVa

Green
VIb, c

1514-61

2019-10

2072- 1

- 9

2044, 2560, 2561 ....

2425, 2931, 2932

4333, 43S4

4335

4899-4904

5107

5222

44
19
38
22
153
50
46
44

14

3

12

13

58
16
18
15

16

6

10

7

1

2956- 2

4035-33

73

24

4068- 6

26

-17

5223

11

Total, 8 progenies . .

416

149

173

2361- 1

4070- 6

4424,4425

5235, 5236

14
133
62
30
15
30

4

51

21

11

6

9

4
52

-11

5237,5238

6696, 6697

A416, A417

A407, A408

19

5269- 3

15

2

A9&-14

4

A97-29

13

Total, 6 progenies

274

102

107

6790-1x6809-8

7292

26

20

56

TABLE 23. F2 Progenies of the Cross Sun Red Ila x Brown V

Pedigree

nos.

Number of F2 plants

Fi

F2

Purple
la

Sun red
Ila

Brown
V

Green
Via

5192-1

A99

14
37
69

4

5

20

5

9

23

1

-2

-3

7767

7766, S23

2

7

Total, 3 progenies

120

29

37

10

138 R- A. Emerson

TABLE 24. Fj Progenies of the Cross Sun Red Ila x Dilute Sun Red IVa

roup

Pedigree nos.

Number of F2 plants

Fi

413- 1.

617-11.
1520- 9.
2065- 1.
- 2.
2414- 2.
2975- 4.
4028- 3.
4040- 3.
4332-26.
4787- 4.
5165- 2.
7224- 4.
7359- 1.

1298

1235

2017

4330

2431,4331

2987-2992

4983-4986,7001,7002

5643-5646

5150,5151

5491-5493

6779-6782

A114

8118,8119

8170, 8171

7854- 1 8094, 8095 .

A119- 4 i A227

Total, 16 progenies .

Fi X IVa

2065- 1 X 2043-

2

- 2x

2

4714-11 X 4774-

1

7224- 9 X 7225-

7

7354- 1 X 7315-

5

7770- 1 X 7768-

172

- 5x

172

A140-14X A105-

6

L1773-15 X L2049-

11

-20 X

10

L1844-14 X L2048-

24

L2063- 5 X

8

-26 X L2049-

3

L2064- 2 X L2048-

22

4329

2432,4332

6943, 6944, 7676, 7677

8115,8116

8250, 8251

8731

8732

A252, A468

8741

8742

8743

8746

8745

8744

Sun red
Ila

Total, 14 progenies.

40
15
31
14
48
36

373
22
41
55

166
55
43
9
35
15

998

27

6

173

196

86

16

17

92

46

41

37

56

7

11

811

Dilute

sun red

IVa

13

4

8

5

15

9

123

7

8

16

50

20

12

3

15

6

314

30

13

133

180

96

14

11

87

37

39

41

48

7

6

742

Plant Colors in Maize

139

TABLE 25. F3 Progenies of F2 Sun Red and Dilute Sun Red Plants of the Cross
Sun Red Ila x Dilute Sun Red IVa

Pedigree nos.

Number of F3 plants

Group

F2

Fa

Sun red
Ila

Dilute

sun red

IVa

2990- 1

5776-5778

10

4133-26

5366

40

1

Total, 2 progenies

50

2991-1

-4

5779,5780

10
9

5781

2

Total, 2 progenies

19

7001-7x7002-11

7684,7685

101

1235- 1

1298-14

2987- 2

1633-1635, 2009.. . .

2011

4997, 4998, 6999, 7000
4999

23

• 14

324

12

10

2

111

3

- 9

4

Total, 4 progenies

373

127

TABLE 26. F2 Progenies of the Cross Dilute Purple Illa x Dilute Sun Red IVa

Pedigree nos.

Number of F2 plants

Group

Fi

F2

Dilute

purple

Ilia

Dilute

sun red

IVa

48.3- 3

848- 2

884

16
20
47
69
65
27
17

5

1574

10

2425- 2

4040- 1

2946,2947

5145-5147

5240-5242

52ai

A226

16

26

1

4070- 8

18

-15

8

A119- 3

4

Total, 7 progenies

261

87

F, xIV

7317- 6x 7322- 4

AlOO- 6x A140-31

8204, 8205

A249, A467

A250, A251, A465,

A466

8739

18
85

83
56
33

22
95

A140-12 X A105- 3

2

L1760- 6xL2026-15

L1838-16X -15

51
63

8738

32

Total, 5 progenies

275

263

140 R. A. Emerson

TABLE 27. Fi Progenies of the Cross Sun Red Ila x Dilute Purple Ilia

Pedigree nos.

Number of Fi plants

Group

Pi

Fi

Purple
la

Sun red
Ila

Dilute

purple

Ilia

1529-18x1542-8

6889- 1x6835-1

2057

10
14

7627

1

24

2

2903-2x2947-37

^1796-4799

74

75

488- 9x 730- 3

1529-15x1549-35

842, 1389

18
10

23

2058

6

3

28

29

TABLE 28. F2 Progenies of the Cross Sun Red Ila x Dilute Purple Ilia

Pedigree nos.

Number of Fo plants

Fi x IVa

F2

Purple
la

Sun red
Ila

Dilute

purple

Ilia

Dilute

sun red

IVa

6650- 9 x 6691- 8

7337

8

7

9

13

8

19

35

12
7
8
10
14
22
37

13
5

6
12
14
18
36

6

6651-10 X - 8

73.38

6

7700- 4x7768-172

-14 X -172

7769- 2 X -172

- 5x7315- 10

- 7x - 9

8723,8724

8725,8726

8729,8730

8263,8264

8261,8262

5
15
12
15
24

Total, 7 progenies

99

110

104

83

Plant Colors in Maize

141

TABLE 29. F2 Progenies of the Cross Purple la x Dilute Sun Red IV&

Group

Pedigree nos.

Fi

478- 3.

- 4.
47^ 1.
484-24.

-26.
739- 1.

849- 1.

850- 3.

851- 2.

- 3.

852- 1.

- 2.
1564-15.
2971- 3.
4028- 1.

- 6.

4045- 3.

4046- 4.
4070- 4.

-12.
5165- 8.
5172- 3.

5179- 1.

- 6.

5180- 5.
S12-18.

880

881

883

907, 1531

828, 1396, 1530. .

1312, 1549

1553, 1554

1559

1563

1565

1566, 1567

1568

4102

4968-4976

5647

5082, A66

5154

5159,5160

5239

5232,5233

A117

A126

A130

A131

A133

A208

Number of F2 plants

Purple
la

Total, 26 progenies.

53
49
43
39
74
97
40
10
23
16
14

2
13
65
17
138
40
65
34

7
40
17
42
12
36
27

FixIVa
740- 2 X 732- 1
1105- 9 X

-15 X

-16 X
1106-12 X
1107- 4x

-13 X

849-

852-
848-
851-
850-
2922-19 X 4046-

4045- 3 X 2922-18 .

4046- 4x4042- 2.

4729- 8x5165- 8.
5812- 3x5179- 6.
6785- 1 X 6784-18.
- 1 X -26 .
722C- 2 X 7268- 2.
7263- 9x7240-10.
A140-18xA106-4.

1118, 1119

1557, 1558

1561, 1562

1570, 1571

1572, 1573

1564

1560

5161, 5162, A142
A143

5155, 5156

5164, 5165, A105-

A107

S12

A132

7429, 7430

7431, 7432

8111

8008

A248, A469

1,013

Total, 17 progenies.

39
15
11
13
9
4
10

37
23

26
7
6
10
31
33
14
35

323

Sun red
Ila

18

20

15

11

25

27

10

5

5

4

5

0

2

22

5

41

10

23

10

1

14

7

15

1

11

9

Dilute

purple

Ilia

316

33
14
11
10
6
6

34
17

23
2
9
14
31
30
15
44

306

12

11

12

13

23

28

14

0

3

7

3

1

1

23

5

45

13

18

9

2

13

6

11

4

10

9

296

36
14

7
12
12

8
12

39
13

27
5
3

17
36
32
18
34

325

Dilute

sun red

IVa

4
5
3
5
10
8
2
1
0
1
1
1
0
8
0
14
5
6
3
2
5
1
7
3
3
2

100

35
15

8

11

9

4

8

30

17

26

5

5

9

26

27

14

40

289

142

R. A. Emerson

TABLE 30. F3 AND r4 Progenies of F2 and Equivalent F3 Purple Plants of the
Cross Purple la x Dilute Sun Red IVa

Pedigree nos.

Number of F3 plants

Group

F2

F3

Purple
la

Sun red
Ila

Dilute

purple

Ilia

Dilute

sun red

IVa

271- 9

496, 497,722

1535, 1577

1536, 2002

5177

6742, A68

6743, A69

A147

34
35
42
25
48
74
10

11
13
14

8
24
32

3

9

9
10

8
18
22

2

5

1312-52

1

-59

2

4102- 2

3

5082-23

8

1

-33

9

5159- 3

0

268

105

78

28

1312-59 X 1140-18....

1575, 1576, 2000,
2001

26

25

24

21

271- 5

489, 490

12
34
14

5

16

1

1312-87

1537

A149 :

5160- 8

60

22

2

148- Ix 271- 5....
1312-87 X 1140-18....
4102-13x4042- 2....

478, 479

12

9

11

6
13
12

1578

5179, 5180, Al 13.

32

31

271- 3 . 1 492. 493

49
44
43
26

10

18

11

9

1312-50

1534

-

-81

1581

4102-12

5178

3

Total 4 progenies

162

48

271-12 X 80-8

483, 484

17

15

F3

F4

Number of F4 plants

4

722- 5 X 720- 1 . . . .
A68-31

739,762,856,1550.
A339

41
13

54
5

722-3 X 719-3

-3x 721-7

740, 761, 849, 850.

848

40
12

44

8

5

Total, 2 progenies

52

52

6

722-1

724-1 x 722-1

760,905,1121,1526

857

69
18

Plant Colors in Maize

143

TABLE 31. Fa Progenies of Sun Red, Dilute Purple, and Dilute Sun Red F2 Plants
OF THE Cross Purple la x Dilute Sun Red IVa

Pedigree nos.

Number of F3 plants

Group

F2

Fa

Sun red
Ila

Dilute

purple

Ilia

Dilute

sun red

IVa

1312- 4

1579

17

18
18

-36

1542

-55

1543

53

1

1312-38

5159- 8

1580,2010

A148

24
14
16
16

7
5

A 13'^- 3

A233

7

A133-12

A193

5

70

24

80-4

271- 4

487 488 . .

30
50
17

494

A117-12

A473

97

271- 1

- 7

491

55
42
46
36
11
27

25

2

495

16

1312- 3

1538

16

-65

1539, 1999

12

5234- 1

- 8

A86

5

A87

12

Total 6 progenies

217

86

80- 8

485, 486

19

1312-11

1544, 1872

27

3

A133- 3

A192

26

72

144 R. A. Emerson

TABLE 32. Fj Progenies of the Cross Weak Sun Red lib x Dilute Sun Red IVa

Pedigree nos.

Number of F2 plants

Fi

F2

Weak

sun red

lib

Dilute

sun red

IVa

2187-21

4135,5371

4133, 5365

151

160

112

122

99

176

141

17

35

89

17

181

41

-23

59

2189-16

4138,5377

5373

4142, 5374

4143, 5376

2391,4144, 5375,7072. ..
5715

25

2190- 4

44

- 4 X 2187- 1

42

- 7 X -23

75

- 7

49

4022- 5

7

4134-22

5370

14

-56

5378

5411

A58

27

4162-41

3

5364- 6

43

Total, 12 progenies

1,300

429

TABLE 33. F3 Progenies of the Cross Weak Sun Red lib x Dilute Sun Red IVa

Pedigree nos.

Number of F3 plants

Group

F2

F3

Weak

sun red

lib

Dilute

sun red

IVa

1

4136-43

5384,6805,7740

77

4136-11

5383, 6802

86
22
13

7

39

4138-15

5385

8

2

5365-26

5371-23

A61

5

6798

2

128

54

3

4143-23

5392, 5393

95

Plant Colors in Maize

145

TABLE 34. F2 Progenies of the Crosses Weak Purple lb x Dilute Purple Ilia,
Weak Purple lb x Dilute Sun Red IVa, and Weak Sun Red lib x Dilute Purple
Ilia

Pedigree nos.

N

limber of F2 plants

Group

Fi X Ilia, IVa

F2

Weak

purple

lb

Weak

sun red

lib

Dilute
purple
Ilia

Dilute

sun red

IVa

A208-15 X A445- 1.

A452- 4x 7302- 4,

-18 X -44.

A822

4
53

84

4

57
102

1

A789, A790

A791, A792

Total, 3 progenies

141

163

7507- 2x A43S- 5..
A292-17 X A441- 6. .
A441- 2x 7515- 3..

- 6x - 8..

- 7x - 8..
-12x A339-10..
-18 x 7515- 4..

A793-A796

A788

77
55
76
64
68
64
77

86
58
80
68
60
70
104

61
49
69
69
66
69
77

56

38

108

88

A783

A784

2

A785

53

103

91

A786

A787

Total, 7 progenies

481

526

460

'i'^7

3

S27-2 x 6805-9 j 7773, 7774. .......

21

28

22

27

TABLE 35. F2 Progenies of the Cross Green IVg x Brown V

Pedigree nos.

Number of F2 plants

Fi

F2

Purple
la, g

Sun red
Ila, g

Dilute

purple

Ilia

Dilute

sun red

IVa

Brown
V

Green

Illg.

IVg, VI

2400- 1

2952- 1

-11

-24

-32

2958-2961 . . .
4844-4860 . . ,
4861-4871 . . .

4872-4884 . . .
4885-4898 . . .
4822-4829 . . .

19
59
43
42
62
84

5
21
15
12
23
24

6
8
7
9
12
25

1
1
4
2
3
8

5
14
11
15
20
23

2
18
15
16
17

2953-10

30

Total, 6 progenies

309

100

67

19

88

98

146 R. A. Emerson

TABLE 36. Fj Progenies of the Cross Green IVg x Brown V

Number of Fj plants

Pedigree nos.

Purple

Sun red

Dilute
purple

Dilute
sun red

Brown

Green

Fi

Purple

anthers

la

Green

anthers

Ig

?
an-
thers
I

Pink

anthers

Ila

Green

anthers

Ilg

7
an-
thers
11

Purple

anthers

Ilia

Pink

anthers
IVa

Green

anthers

V

Green
anthers

Illg,
IVg, VI

2958-2961

4822-4829

4844-4860

14
61
42

5
12
16

0

11

1

1
10
10

1

4
7

3
10
4

6
25

8

1

8

1

5
23

14

2
30
IS

Total, 3 progenies .

117

33

12

21

12

17

39

10

42

50

TABLE 37. F^

Progenies

OF THE

Cross Purple Ig x Green Vie

Pedigree nos.

Number of F2 plants

Group

F.

F,

Purple

Sun red

Dilute

purple

Ilia

Dilute

sun red

IVa

Brown
V

Green

5534-39

6795, 6796..
7376

(la. g)

65
15

(Ila. g)

11
2

6
3

7
2

15
- 5

(Illg,
IVg, VI)
26

1

6655- 6

1

80

13

9

9

20

27

2

F, X Vic

6655- 6x6690-17..
6808-13x6790- 8..

7349

7290

(la)

6

30

(Ila)
13
16

13
18

15
16

17
14

(VI)
46
49

36

29

31

31

31

95

Fi X IVa
6779-2x6790-8.. ..

6792-2 X -8

-8x -8....

7299,7300..

7297

7296

27
29
59

25
29
43

30

19
46

31
32

48

3

Total, 3 progenies

115

97

95

111

4

Fi X IVg
6656-9x6652-6

7344

(la, Ig)
23

(Ila, Ilg)
15

10

15

(Illg, IVg)
13

Plant Colors in Maize

147

TABLE 38. F2 Progeniks of the Crosses Purple Ig x Dilute Sun Red IVa and Purple

la X Green IVg

Pedigree nos.

Number of F2 plants

Group

Fi

F2

Purple
la, g

Sun red
Ila, g

Dilute

purple

Ilia

Dilute

sun red

IVa

Green
Illg, IVg

1

2954-3..

2956-3..

-4..

5042-5045 .
4905-4914.
4915-4929.

43
144

56

14
42
15

13
25
21

5

14

3

7
7
6

Total, 3 progenies. . . .

243

71

59

22

20

2

2421-1 . .

-2..

2910,2911.
2908, 2909.

14

26

7
13

5
4

1
1

1
0

Total, 2 progenies. . . .

40

20

9

2

1

TABLE 39. F3 and F4 Progenies from Fo and Equivalent F3 Purples of the Cross

Purple la x Green IVg

Pedigree nos.

Number of F3 and F4 plants

Group

F2 and F3

F3 and F4

Purple

Sun red

Dilute

purple

Ilia

Dilute

sun red

IVa

Green

2909-16

5251, 5252

(la, g)
9

(Ila, g)
4

3

0

0

1

F2 X IVg
2909-4 X 2884-21

5255

15

15

5

1

(II Ig, IVg)
9

F2 X VIc

2909-4 X 2887-38

.5^56. A 94

(la)
27

(Ila)
19

15

14

2

5251-6 1 6708

31

7

2909-9

5257, 5258
6652

(Ig)
14
23

(Ilg)
2

9

5

3

5252-1

9

Total, 2 progenies

37

11

14

148

R. A. Emerson

TABLE 39 (concluded)

Pedigree nos.

Number

of F3 and F4 plants

Group

Fa and Fj

F3 and F4

Purple

Sun red

Dilute

purple

Ilia

Dilute

sun red

IVa

Green

3

(coiv-
tin-

Fa, F3 X IVg
2909- 9 X 2884r-21

4717-71 X 5252- 1
5252- 1 X 5669- 3

5259, 5260,
7007, 7008,
7060, 7061.

6654A

6654B

(Ig)

19

11

4

(Ilg)

IS
8
6

(Illg, IVg)

34

13

6

Total, 3 progenies

34

32

53

ued)

F2, F3 X Vic
2909- 9 X 2887-38
4057- 1 X 2909- 9
5251- 1 X 5813-18
5813-18 X 5251- 1

5261,5262.
5534, 6790.

6655

6656

(la)

14

- 16

9

5

(Ila)
11
10
16
11

7

13

7

6

11

18

14

9

Total, 4 progenies

44

48

33

52

2909-34

5253, 5254,

7090

6658,7015.

(Ig)

26
30

(Illg)

5251- 7

6
12

4

Total, 2 progenies

56

18

Fa X IVg
4717-20 X .5251-7. .

6659, 7014.

28

27

Plant Colors in Maize

149

TABLE 40. F3 AND Equivalent F4 Progenies from F2 and F3 Sun Reds and Dilute
Purples of the Cross Purple la x Green IVg

Pedigree nos.

Number of F3 and F4 plants

Group

F2 and F3

F3 and F4

Sun red

Dilute

purple

Ilia

Dilute

sun red

IVa

2090-20

5278

(Ila)

. 30

37

30

8

5251- 8

6648

10

1

-10

6709

8

Total, 3 progenies

97

26

2909- 8

5270-5273

5280-5283

5274-5277

(Ila, g)

43

64

121

-26

-32

Total 3 progenies . .

228

2

F2 X IVg
2909-26 X 28M-35

Fo X Vic
2909-26x2887-38

5284-5287,7137.

5288, 5289

41

(Ila)
67

Total, 2 progenies. . . ....

108

2909-21

5265,5266

46

9

3

F2 X IVg
2909-21 X 2884-35

5267,5268

5269

44
41

31

F2 X Vic
2887-31 X 2909-21

51

Total, 2 progenies

85

82

150

R. A. Emerson

TABLE 41. F2 Progenies of the Cross Purple Ig x Green IVg

Pedigree nos.

Number of F2 plants

Group

Fi

F2

Purple

Sun red

Dilute
purple
Ilia

Dilute

sun red

IVa

Green
Illg, IVg

5255 - 6

7094, 7095,

7701,7702

7010,7011.

7375

7365

7366

7368, 8491 .

7378

7377

(Ig)
80
54
23
28
11
43
21
33

dig)
24
22

7
12

3
17

7
13

5259 - 3

55
25

6654B- 3

9

6659 -15

12

1

-22

5

-27

24

6660 - 9

10

-12

10

Total, 8 progenies

293

105

150

Fi X IVa
6659-19 X 6691-8..
6660- 3 X -8. .

Fi X Vic
6654A-2 X 6690-9

B-1 X -17

7339

7340

7335

7336

( la)

14

9

20
15

(Ila)

9

11

15

26

14

12

13
23

12
11

10
37

2

Total, 4 progenies .

58

61

62

70

TABLE 42. F2 Progenies of -

rHE Cross Dilute Purple Ilia x Green IVg

Pedigree nos.

Number of Fo plants

Group

Fi

F2

Dilute

purple

Ilia

Dilute

sun red

IVa

Green
Illg, IVg

1

2403-1

2962-2966

23

8

10

2420- 1

2904, 2905

5038-5041

6826, 6827

6828, 6829

6669, 6670

6675-6678

6679-6682

17
63
36
78
31
41
62

5
26

8
32
16
14
12

9

2954- 4

34

2967- 2

17

-11

31

2

5263- 4

8

5267- 5

27

-12

22

Total, 7 progenies

328

113

148

3

Fi X IVg
7322-3x7317-4

8210-8213

46

45

86

Plant Colors in Maize

151

TABLE 43. F3 and F4 Progenies from Fa and Equivalent F3 Dilute Purples, Dilute
Sun Reds, and Greens, of the Cross Dilute Purple Ilia x Green IVg

Pedigree nos.

F2 and F3

2966- 7.
5049-25.
5050- 6.

F3 and F4

5049-5055

6.S16-6818, 7441

6822-6824, 7058,7059.

Total, 3 progenies.

6676-12 1 7383

6828-12 7658-7660.

Total, 2 progenies.

Number of F3 and F4 plants

Dilute

purple

Illa

50
52
41

143

26
14

40

Dilute

sun red

IVa

Green

48

14

(Hlg, IVg)
26
20
27

73

16

7

23

5052-7.
6676-8.

6825, 7323, 7442.
7382, A266

Total, 2 progenies.

5049-37 6819-6821.

2905-22.
5053- 1.

2547-2550

6875, 6911, 6912.

Total, 2 progenies .

5050- 1.

5054-10.

5055- 2.

- 5.

6874

6745, 6872, 6873.

6871,7315

7515

Total, 4 progenies .

27
55

82

23

62

(Illg)
16

21
42

(IVg)

9

13

63

22

17

108

51

21

197

290.>- 5

-19

5049-

-13

5052-

-3

- 0

-12

6829- 9 1

5243, 5244 .
5245, 5246 .
6913, 6914.
6833

S5

6832

7655-7657.

Total, 7 progenies.

(Illg, IVg)
5
13
11
24
15
32
30

130

152

R. A. Emerson

TABLE 44. F2 Progenies of the Crosses Sun Red Ilg x Green IVg, Sun Red Ila
X Green IVg, and Dilute Sun Red IVa x Green IVg

Pedigree

nos.

Number of F2 plants

Group

Fi

F2

Sun

red

Dilute
sun red

Green

Pink

anthers

Ila

Green

anthers

Ilg

Pink

anthers

IVa

Green

anthers

IVg

1

4787-6

52&4-3

6983,6984

7003-7006

122
94

52
25

Total, 2 progenies ....

216

77

2

Fi X IVg

7317-6 X 7318-4

7318-1 X 7317-4

-4x -6

8214-8217

.8222-8225

8218-8221

22
38
45

31
25
34

24
34
47

32
26
51

Total, 3 progenies

105

90

105

109

5267-3

6671-6674

.7725,7726

55
30

22

3

F, X IVg
7031-14x6857-5...

30

Plant Colors in Maize

153

TABLE 45. Fi Progeotes of Crosses of Sun Red Ila and Dilute Sun Red IVa with

Green Illg and IVg

Pedigree

nos.

Number of Fi plants

Group

Pi

Fi

Purple
la

Dilute

purple

Ilia

Dilute

sun red

IVa

Green

Ila X Illg
7097-5 X A 159-25. ..
7357-3 X 7356- 1 . . .

7710

33
31

8151,8152

1

Total, 2 progenies

&4

IVa X Illg

A9-22X 7097-1

7709

4

IVa X IVg
6860- 8x6869-1....
A9-14X 7060-1.. ..

7713

28
31

7708, A283, A284

Total, 2 progenies

59

IVa X Illg

6860-13x6871-39...
6861- 2 X 6751- 3. . .

7714

11
9

12

18

2

7711

Total, 2 progenies

20

30

IVa X Illg

6861-4 X 6882-5

7039-3x7061-1

7512, 7513, 7716.

7727,7728

25
44

11
43

(Illg, IVg)
34
72

Total, 2 progenies

69

54

106

IVa X Illg

7312-8x7313-2

7313-2 x 7314-1

7314-1 X 7313-1

-6x -2

8183

86

31

126

85

(Illg)
92

8184

19

3

8200, 8201

8185

129
98

Total, 4 progenies

328

338

154

R, A. Emerson

TABLE 46. F2 Phogeniks of the Cross Green IVg x Green Vie

Pedigree nos.

Number of F2 plants

Group

Fi

F2

Dilute

sun red

IVa

Green

5534-4

6791, 6792

7179,7180

7181, 7182

7177, 7178

7175,7176

7163,7164

7169, 7170

7171,7172

35
51
32
64
63
52
60
63

(IVg, Vic)
29

6530-1

43

-2

30

6531-1

42

1

-2

38

7032-1

39

7036-3

36

7037-2

34

420

291

Fi X Vic
7032-7 X 6878-42

7729,7730

7767,7768

24
42

iVIc)
24

7034-5 X -42 .

34

66

58

2

Fi X IVg
7037-4 X 7049-7

7173, 7174

7731,7732

48
48

(IVg)
50

7049-1x7037-4

46

Total 2 progenies

96

96

TABLE 47. F3 Progenies of F2 Dilute Sun I

Green Vie

Ied Plants of th

E Cross Green xVg x

Pedigree nos.

Number of F3 plants

Group

F2

F3

Dilute

sun red

IVa

Green
IVg, Vic

6791- 3

7148,7149

7154,7155

7159

23
69
16

19

6792- 6

45

1

-11

13

Total, 3 progenies

108

77

6791-22

7150, 7151

7152,7153

7157

7158

7160

65
49
38
23
12

23

-23

18

6792- 7

12

2

-10

10

-13

3

Total, 5 progenies

187

66

6792- 5

-25

7156

7161

48
30

3

Total, 2 progenies

78

Plant Colors in Maize 155

TABLE 48. Fa and F3 Progenies of the Cross Green IVg x Green Via

Pedigree nos.

Number of Fa and F3 plants

Group

Fi

Fa

Sun red

Dilute

sun red

IVa

Green

2400- 2

2952- 5

-22

2902,2903

4838-4843

4830-4837

4810-4813

4814-4817

4818-4821

4930, 4931

(Ila, g)

7

36

99

88

111

92

153

3
3
15
32
20
30
58

(IVg,VIa,c)

5

18

57

1

2953- 4

- 7

-21

2957- 2

59

62

45

102

Total, 7 progenies

586

161

348

2

Fa
4930-31

F3
6991,6992

119

2903- 2

4930-22

4783-4786

6993, 6994

(Ila)

99

130

(Via)
32
39

3

Total, 2 progenies

229

71

Fa X IVa
2903-2x2889-38

4787-4790

55

156

R. A. Emerson

TABLE 49. F2 Progenies of the Cross Green Illg x Green Vie, and Fi Progenies of
Crosses of F2 Greens with Sun Red Ila and Dilute Sun Red IVa

Pedigree nos.

Number of F2 plants

Group

Fi

F2

Purple
la

Sun red
Ila

Dilute

purple

Ilia

Dilute

sun red

IVa

Green

Illg, IVg,

VIb, c

2907-8

5297,5298..

7085, 7086,

7722, 7723

28
81

11
26

38

5262-5

1

97

Total 2 Droeenies

lotai,^ progenies

109

37

135

Pi

Fi

Number of Fi plants

Illg X Ila
7085-10 XA159-24.

7717

27

2

Illg X IVa
7086-2 X 7102-7. . . .
-3 X -8. . . .

7207

7719 .

14
25

Total, 2 progenies . .

39

3

Illg X Ila

708&-6X A159-17..

Illg X IVa
708&-4 X 7102-8. . . .

7718, A298,
A299

7720

28

41

11

9

4

IVg X IVa

7086-8 X 7102-8. . . .

7721

22

Mkmoik 39

Plate I

ANTHER, GLUME, AND RACIIIS COLOR OF PURPLE

1, Purple, type la, typical, anthers purple: 2, type la with »■'"'', anthers near-
black ; 3, type la with i>r, anthers reddish ; 4, type Ij;. with Jiy or r'J, anthers yreen
U'rawings by C. \V. Kedwood, somewhat diagrammatic)

Mkmoir 39

Plate II

CW.f^a.dv-/-ood

AXTHER, OLT-ME, AXD RACHIS COLOR OF T^ILFTE PT'RPLE .\XT> OREEX

4. Groon, typos Ilii: a.ul IVf: with R<J or rr/. ^n-oon (hruout

(Drawings by C. W. Redwood, somewhat diajjramniatie)

ilEMOIR 39

Plate III

I

ANTHER, GLUME, AXD KACIIIS COLOR OF SIX REP AXP DILUTE SUX RED

1. Snn red, type Ila. intonsoly pi.smenterl form

2. Dilutf sun rorl. tyi.p IVa. intensely pipniontc.l f,,rm : .". an.l 4. near-sreen
forms, little col., r in ^lnnl.■s. nntli.-rs preen witli reddish stipplins as shown in
enlarged anther

fr)rawings by C. W. Redwood, somewhat diagrammatic)

Mkmoih n9

Plaie IV

\

AXTIIER, GLUME, AXD RACHIS COLOR OF BROWX AXD GREEX

1. Brown, type ^'. intensely pipmented, homozygous form : 2. typo V. less
intensely pigmented form, heterozygous for B or PI or both

3, Green, type Vic : 4. type VIb, green with tinge of brown due to PI and r'''
(Drawings by C. W. Redwood, somewhat diagrammatic)

Mkmuiu 39

Platk V

CULM, IirSK, AND SHEATH COLOR OF PIRPLE AXD SUX RED
1, Purplo, tj-pe la; 2, weak purple, type II)

3, Sun red. t.vpe lla ; 4, weak sun "red. iy]n- Ilh; r,, t.vi»^ Ilh. inner luisks of
lower ear hiphly colored from exposure to sunlipht directly after beinj; torn apart
(Drawings 1 and 3 by C. W. Redwood; 2. 4, and 5 by Bernico M. Branson)

Memoir 39

Plate VI

CW-Kcdwood

CL'LM, inSK. AND SHKATIT COLOR OF DILUTK PfRPLE. -nTIXTTE SUX RED,

liKOWX, A.ND GREEN

1. Diluti' purpip anrl dilute sun red, types Ilia and IVa ; 2, more hishlv colored
fonri of tjiies Ilia and IVa

'■'.. I'.iown. type V

4. (Ir.-on, types VIb and VI<- : n. type Via. with some brown in outer husks
due to li

(Drawings by C. \V. Kedwood)

Mkmoik 3!)

Plaik VII

\
2 ^iJ/

'W

iLVTURE CULM, HUSK, AXD COB COLOR
1. Purplo. typo Ta ; 2, sun red. type Ila : 3. dilute purple, type Tlla : 4. more
intensely pigmented form of type llla: .". l)ro\vn. type V: C, dilute sun red.

type IVa

(Drawiugs by Carrie M. Preston)

Mkmoiu 39

Plate VIII

DEVELOPMENT OF COLOR IX DARKNESS
Tasspls ami slionths di'veloped iinrter Ijlack paper liaes : 1. purjilc. type la •
2, brown, type V: 3, dilute purple, type Ilia: 4, sun red, type Ila, no red color
(Drawings by Carrie M. Preston)

H U

H

c

a

i-I

>,

^

H

K

r— ■*■

^

K

^

f<i

t^

=^

0)

i-l

- --

.i;

h- 1

p- —

P

o

K X

m

o^

* ■^

[i(

O

^ ^

>j

!^

'" "tli

iH

o

*^

M

<*-4 '

tc

H

°.s

a

-2 '-

L

Memoir 39

Plate X

COLOR DEVELOPMEXT IX BROKEN LEAVES

1. nihitp sun red. type IVa. about one week after the leaf was creased-
2. dilute purple, type Ilia with japc.nica white stripe.s, about three days after the
leaf was creased

(Drawings by Carrie M. I'reston)

ilKMOIH :i9

Plate XI

md

^\i'j

y

1 ♦

r%

r

ABERRANT COLORATIOX OF BROWX TASSEL

Toorly flfveloped tassels of brown, tvpo V soin(.fini..v; ,.vi,n,if ,, , • ,
developed parts ^oiiKtinns (.xinl.it purple m al)norman.v

(Drawing by Carrie M. Preston)

Syracuse, N Y

P*I IAN. 21. 1308

, i - ,*A'