THE EISENHOWER UBRABV

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SOME RELATIONS OF MAINTAIl^ED TEMPEHATUPES ?0

GEHMI^TATIOn AKD THE EARLY GROT^TH RATE OF

7,'HEAT IN NUTRIEUT SOLUTIOTTS.

By ?7,F.Grerioke

Dissertation submitted to the Board of University

Studies of the Johns Hopkins University

in conformity with the requirements

for the degree of

Doctor of Philosophy.

Baltimore, 1921.

vl^'

M'^

SOME RELATIONS OF MIJITAINED TEIIPSRATUEES TO

GERlilMTIOl? AITD THE EARLY GROWTH RATE OP

WHEAT IN NUTRIENT SOLUTIONS.

Contents.

INTRODUCTION

EZPERII^IENTATION

Materials and method

The wheat

The salts

The distilled water

The nutrient solutions

The cultures

The tanperature controls

Measurements and results

Introduction

Viability, growth, and solution conposition

Growth-— temperature relations

Introduction

Temperature relations for the entire

(1)

Botanical contribution from the Johns Hopkins
University, I'o .

culture period
Temperature relations of cultures in dis-
tilled wata-
Temperature relations for the last S4 hours

of the culture period
Temperature relations for the first part

(about 86 hours) of the cultiare period
Graphs of the growth-temperatxire relations
Temperature coefficients for shoot elongation
C01?CLTJSI0irs
StM!.!ARY
LITERATURE CITED

SOr.!LE RELATIONS OF IjIAINTAINED TELDPERATUEES
TO GERMIKATIOIT AM) THE EARLY GRO:^TH OF
TREAT IN miTRIENT SOLUTIOTIS.

INTROmJCTIOn.

In the autumn of 1918, the Cononittee on the Salt
Requirements of Certain Agricultural ^lants of the United
States National Research Council, inaugurated a coopera-
tive study of t he is-rowth of wheat plants in nutrient
solutions. 'this prospective cooperation was to involve
the carrying out of comparative experimental tests with a
large number of nutrie nt s olutions, these solutions differ-
ing according to a ref^ular scheme. For a beginning, several
different somewhat arbitrarily selected developmental phases
of the wheat plant were to be studied. It was realized that
a nutrient solution might be well suited for good grov/th
during one phase of the plant's development and not so for
another phase. All cooperators were to use seed from the

''^'Livingston, Burton E. (Editor). A plan for
cooperative research on the salt requirements of represent-
ative agricultural plants, prepared for a special committee
of the Division of Biology and Agriculture of the ITational
Research Council. 2nd Ed. 54pp.., Baltimore, 1919.

-2-

same lot and all v/ere to follov/ the s?me general methods,
so that their results mi^t be relatively comparable.

The aim of the cooperation was to find out what
salts, salt proportions, and total concentrations of the
media, night gener^aOy produce the best grov/th of the
standard plant for each of the developmental phases
employed, and what ones might give good grov/th for
certain kinds of aerial environments... The "Marquis"
variety of spring wheat was selected as the test plant.
Pour phases of development v/ere outlined for studyl

rfU

"(1) Germination phase, from beginning of soaking
till the shoot is four centimeters high, measured from ■"/(.
seed to the tip of the shoot. (2) Seedling phase::, from
the end of phase 1 for a period of five weeks, without
regard to tbe size of the plant. (3) Vegetative phase,
from the end of phase 2, until the first appearance
of flowering in the controls. (4) Reproductive phase,
from the end of phase 3 until maturity is reached by the
Best five cultures.

The Solutions to be tested were planned on the
basis of the scheme suggested by Livingston and Tott Ingham^ ^ ,

(3 )

'Livingston, B.R., and. Tott Ingham, V/.E. A

new three-salt solution for plant cultures. Amer. Jo\ir.

Bot. 5:357-346, 1918.

follov/ing the general out lines v;orl<ed out by Schreiner and

(4)
Skinner* and other v/riters, for the experimental study of

different proportions of the same salts as such differences

influence plant grov»'th. The Livingston-Tottingham scheme

embraces what they call six types of solutions, each being

characterized by the three main salts employed. All

solutions were to lirve a trace of iron as ferric phosphate,

the amount of tiiis salt used for unit voliame of solution

being alviays the same. ITae three main salts for each

(4)

'Schreiner, 0., and Skinner, J.J. , Ratio of phos-
phate, nitrate anr" potassiiom on absorption and gro'.^th*
3ot. Gaz. 50:1-30. 1910.

Idem. Some effects of a harmful organic constituent.
U.S. Dept. Agric. Bur. Soils. Bui. 70. 1910.

Tottinghara, "' .E. A quantitative chemical and physiolog-
ical study of nutrient solutions for p^ant cxiltiire . Physiol.
Res. 1:133-245. 1914.

Shive, J.. 7. A study of the physiological balance in
nutrient media. Physiol. Kes. 1:327-397. 1915.

licCall, A.G. The physiological bal- nc e of nutrient
solutions for plants in sarti cultures. Soil Sci.
2:207-253. 1916.

Idem. The physiological requirements of v;heat and soy
beans growing in sand media. Proc. Soc. Prom. Agric. Sci.
1916:46-59. 1915.

Hibbard, R.P. Physiological balance in the soil solu-
tion. T'ich. Agric. b;xp. Sta . Tech. Bui. 40. 1917.

Shive, J.'V. A study of physiological balance for buck-
wheat grown in tliree salt solutions. N.J. i^gric . rixp. Sta.
Bui. 319.

KcCall, A.G. and Richards, P.E. Mineral food requirements
of \lheBit plant at different sta.es of its development.
Jour. Amer. Soc. Agron. 10:127-134. 1918.

Shive, J. 17. and Martin, ".H. A Comparison of salt require-
ments for young and for mature bixclnvheat plants in water cultures
and sand cultures. Amer, Jour. Hot. 5: 186-191 .1918.

Idem. A Comparative sttody of salt requirements for young
and matiire buck^r/heat plants in solution cultures. Jour, -t^gric .
Res. 14:115-175. 1918.

■ Schreiner, 0., and Skinner, J.J. 'i'he triangle system for
fertilizer exp'^iments. Jour. Amer. Soc. Agron. 10:225-246.1918.

of the six types are shown below:

Type Type Type Type Type Type

I II III IV V VI

KH2PO4 K2SO4 KNO3 K2SO4 KNO5 iai2P04

Ca(N03)2 Ca(N03)2 Ca(H2P04)2 Ca(H2P04)2 CaS04 CaS04

MgS04 Ms(H2K)4)2 MgS04 Mg(N03)2 Mg(H2P04)2 Hg(W03)2

Twenty-one different sets of proportions of the
three/-3alla,were to be tested for each solution type ^ these
sets of salt proportions being conveniently shown by the
\aniform arrangement of twenty-one points on a triangular
diagram, such as v<as first used in this sort of work by
Schreiner and Skinner. The plan defined the several solutions
of each type in terms of molecular proportions of the three
main constituent salts. The solutions are designated by
convenient symbols referring to the serial number of the
row of the diagram in which any solution is represented
(always counting from below upv^ard), and to the serial
number of the solution as represented in the row (alv/ays
co\inting from left to right. Thus RIS2 denotes the second
point in the first (lowest) row of the diagram, which
represents an equilateral triangle with one side ha- izontal
and at the bottom. A Roman numeral prefixed to one of these
symbols -p^^^^yo^ denot^ the serial nuriber of the solution type
as above defined. If tVie three salts are always arranged iri
the same order, according to their cairns, the twenty-one
different symbols (representing the different sets of salt

t6-

proportlons) niay be defined in terms of the relative molecu-
lar proportions of the salts and the same table of symbols
and proportions is equally applicable to all six solution
types. These symbols and the corresponding sets of salt
proportions are sho?m below:

-6-

Solution
Symbol .

Molecular Proportions*

RlSl
R1S2
R1S3
R1S4
R1S5
R1S6

R2S1
R2S2
R2S3
R2S4
R2S5

R3S1
R3S2
R3S3
R3S4

R4S1
R4S2
R4S3

R5S1
R5S2

Potassium

Calcium

Magnesium

salt

salt

salt.

1

1

6

1

2

5

1

3

4

1

4

3

1

5

2

1

6

1

2

1

5

2

2

4

2

3

3

2

4

2

2

5

1

3

1

4

3

2

3

3

3

2

3

4

1

4

1

3

4

2

2

4

3

1

5

1

2

5

2

1

R6

SI

-7-

The following are illustrations of the reading of
the above table. Solution P.2S3 is characterized b;' having
two-eighths of all its salt molecules added in the form of
the potassium salt, three-eighths in the form of the calcium
salt, and twa-eighths in the form of the magnesiiim salt.
Solution R2S1 has two molecules of the potassium salt, one
of the calcium salt and five of the magnesium salt. In
reading these symbols, it may be remembered that the number
following "R" tells how many eighths of all the salt mol-
ecules in any voliime of the given solutions are in the
form of the potassium salt, while the number following the
"S" tells how many eighths are in the form of the calcium
salt. The difference betv/een the sum of these two numbers
and 8 gives the number that! have the form of the magnesium
salt.

It was planned that work should begin by employ-
ing solutions having a total salt concentration such as
would give in all cases a calculated osmotic value of about
1.00 atmosphere of osmotic pressure at 25^C. Other total
concentrations were to be tested in later work.

For further details regarding this series of
126 different three -salt solutions, the reader should refer
to the plan cited above. The experiments to be reported in the
present paper were planned as a part of the cooperation just

-8-

considered. It v/ag decided to confine attention practically

to the germination ]-;hase. This was to be a stvdy of the

inf licences of certain stts of environiaental conditions on

tlie germination and early growth of "Marquis" wheat.

Since the v/heat seed contains a considerable supply

of salts, the general plan of the cooperation was modified

two ways for this study. (1) The total concentration of

every solution was fixed as equivalent to 0.1. atmosphere of

osmotic pressure, the solutions being th\is one-tenth as

concentrated as those considered in the "Plan." (2) llo

this element
iron v/as used, on the sipposition that if / was needed for

germination, the seeds contained svif fie lent amotints of It

to suffice for the germination phase of growth.

On account of the fact that the gennination phase,

as above defined, comprises only physiological processes

that go on satisfactorily in the absence of li^t, it v;as

possible to perform all these tests in darkness. Temperature

control v/as thus possible, and it seemed advantageous to

introduce the temperature factor v;ith this study in a

quantitative way. This was done by using seven different

maintained tempers tures in eveiy test.

11 is study thu.s comprised the testing of the 126
solutions, each with seven different
dlf ferent/n.aintained tem-peratiur-es, giving altogether 882

different environmental complexes. It was expected that,

for any given temperature, some salt combination (i.e., some

-9-

solution] v/ould produce germination and grov/th results
noticeably different from those of other salt combinations,
and that the same salt combination would produce noticeably
different results according to the temperature employed.
As it turned out, the salt combinations, as such, were ap-
parently without any clearly and easily indicated influence
upon the growth phase studied, for any of the seven tempera-
tures tested ( although the study yielded several suggestions
as to salt influence), but the temperatures tested showed a
marked t«mpexatua?^ influence on the germination and early
growth of this wheat.

The experimentation here reported was performed in
the Laboratory of Ilant Physiology of the Johns Hopkins
University, with financial aid from the National Research
Council and with personal guidance and cooperation of
Professor Burton E, Livingston, director of the laboratory.
The experimental work was begun in the fall of 1918 and
completed the following August. The numerical data ob-
tained were studied by the writer upon his return to the
University of California, where the present paper was
prepared. The appreciative thanks of the writer are due to
Professor Livingston, not only for the facilities of the
Laboratory of Plant Physiology of the Johns Hopkins
University, but also for his advice and criticism during
the progress of the experimentation and later while the
present paper was in preparation.

10-

. EXreRIMENTATION.
Materiels end Methods ^

The wheat used was 8 spring wheet^of the "Mar-
quis"'variety, crop of 1918, purchased by the Committee
on Salt Requirements of Agricultural Plants, from the
University Farm, University of Wisconsin. The ae^ds
were not as uniform as work of this kind requires, and

hence ell seeds used in this investigation v,'ere selected by

and uniformity

hand and eye for apparent normality/ Even v/ith this precsu-

A

tion, considerable variation ■was encountered, rot only in the
percentage ©-f viability of the seed, but also in the grov^th
rate of the shoots. It was thought, however, that the sel-
ected grains probably exhibited no greater variability (dif-
ferences in internal conditions) than is generally shown by
agricultural seed vrheat of this variety.

Ths distilled water used for the nutrient solutions

We

was obtained from / Barnstead still of the Laboratory of Plant

Physiology of the Johns Hopkins University.

The salts used for the nutrient solutions were of
the grade of Baker's Analyzed Chemicals, C.P.

The nutrient solutions used all agreed in having
a total concentratir-n corresponding to about 0.1 atmosphere
of osmotic pressiore. They are, tlierefore, to be classed
as relatively dilute. The six solution types differed in
regard to the three salts used in each, as has been shown
above, but all six types agreed in containing the six

-11-

inorganic chemicel elements that (together with iron,
which was not included), constitute the inorganic elements
essential fcr plant grove th in general.

The tv/enty-one different solutions of each type
differed from one another in their molecular salt proportions,
as shown above. The solutions were made up thirty (or, in
some cases, ten) times as concentrated as they were to be
needed, and the stock concentrated solutions thus obtained
were properly diluted whenever culture solutions were

requlr ed.

Nine single-ealt solutions, each representing
one of the nine salts , were first prepared, these
having the following volume-molecular concentrations:
KH2PO4, 1.0 mol.; KNO3, 1 mol.; KgSO^, 0.4 mol.; Ga(HgP04)2,
0.1 mol.; Ca(N03)2. 1»9 mol., CaS04, .014 (satvtrated solution
at room temperature); Mg(H2F04)^ 0. 1 mol.; Mg(N05)2, 1.0. mol.;
MgS04, 1.0 mol. The 126 concentrated stock nutrient solutions
were each prepared by mixing proper volumes of the proper
three single- salt solutions with distilled water in requisite
volume, care being exercised to prevent precipitation.

For solution types I, II, III and IV (without
GaS04), the concentrated stock nutrient solutions were thirty
times as concentrated as those actually used for the culture
tests. For solution types V and YI (with CaSO.i ) , the concen-

■12-

trated stock; nutrient solutions vrere ten times as concen-
trated as those actuall:; used.

The ox-gen and carbonaltfe-dioxide contents of the
nutrient solutions used for the tests were assumed to be
alike; ft is feature of nutrient solution experimaat at ion
has not yet attracted the serious attention/ of physiologists
"but the assumption here made was probably safe , especially
in view of the fact that the -very early stages of growth
here dealt v/ith gave no clearly defined diffarences in growth
that mi^ t be related to the chemical properties of the
solutions.

The cultures were arranged as follows: Glass
tumblers ■ f capacity about 7\00 c.c.) were prepared, each with
a tightly stretched! cover of thoroughly washed mosquito

netting ( cotton thread, with open meshes about S mm.
sqiiare ) tightly sealed to the outside of the wall of the
tumbler by means of paraffin. Each of 13iBse net- covered
tumblers was filled with the proper nutrient solution and
tv/enty-five selected seeds were distributed uniformly over
the netting (the area being about 58 sq.cm,). All seeds
were in contact with ih e solutions, but they were not sub-
merged. This simple method was adopted as the best of
several methods that were compared in preliminary tests.

Each single series of cultures involved but one type
of solution; it comprised twenty-one different solutions,

•13-

each represented by seven cultixt'es. Each sot of seven

like cultures was distributed throughout the seven

Sinp-le
different temperatures tested, so that a/series comprised

twenty-one cultures for each temperature. All of the twenty-
one nt;trient solutions of any one solution type v/ere thus
simultaneously tested for each/the seven temperatures, and
each culture series comprised 147 cultures. The completed
study involved all six types, or 882 cultures. Each
of the six series, excepting those for the lov/est tempera-
ture; , was repeated once^so that 1638 tests were made.
The nuitrient solutions were all renewed after each 24-
hour period, for four renewals, the cultures being
discontinued on the fifth day.

The temperature controls used were those of the
battery of chambers for temperature control at the
Laboratory of Plant Physiology of the Johns Hopkins

University, v/hich has been described in its essentials

(5)
by Livingston and Pavfcett . The seven different

temperatvcres employed in these tests were as follows:

35°, 31°, 28°, 25°, 21°, 17°, and 13° G. Variations from

these values vieve never as great as one degree. No

^ ^■'Livings ton, B.E. and H. S. Fav/pett* A battery
of chambers with different automatically maintained tempera-
tures. Phytopathology 10:356-340, 192Q.

-14-

at tempt was made to control or measijre the chemical
makeup of the air of the chambers. It may be said,
however, that the air hwiidity approached that of satura-
tion for the given temperature in each chamber. Light,
as already stated, was excluded.

15-

Me&s\ireme nts and Results.

Introduction. As has been stated, each
culture solution was removed and replaced by a fresh
one on the second, third, and foiirth day of tiie culture

QD

period, the cixltui^es being discontinued/' the fifth day.

the
These renewals of/solutions did not occur, hov/ever, at

exactly 24 ho\ir intervals and the total length of the

culture period was always less then 5 days. The variation

from the time schedule- was not great in any esse and all

cultures of any series (21 solutions of a single solution

type, vjith eech of the seven temperatures tased) were

subjected to the same time periods between renewals^and to

the same total period. On the third day of the period,

all seedlings v/lth shoots 1 cm. or more in length were

shoot
counted and recorded. On the fourth day, eacb/l cm. long

or longer was measured, and record v/as made showing the
number of seedlings in each culture that were 1, 2, 5, etc..
cm. high. All shoots were again measured on the fifth day,
when the cultures were discontinued. To avoid much disturb-
ance, measiirements made prior to the final one v/ere only
approximately correct, about to a precision of 1 era., but the

fifth-day measurements were carefully made, to a precision of

being
1 mm., each seedling I removed from the solution for

measurement. These two measurements mny be termed

-16-

the first and sec on d ; they occurred after about 86 ani
110 hours, respectively, ^ith variations that will be
noted below. The nvimerical results obtained for each
culture are as follows:

(1) Ntunber of seedlings v/ith shoots 1 era. or
more high after about 86 hours.

(2) Approximate total shoot elongation after
about 86 hours •

(3) Number of seeds germinated after about
110 ho\ars,

(4) Total shoot elongation after about 110 hours.

(5) Total shoot elongation for the last 24 hours
(obtained by subtracting 2 from 4, above ; .

The number of seeds germinated at the end of the
whole period (3, above) may be taken to represent the
viability for any ctilture ; if this nwnber be multiplied
by 4 the product represents the percentage of germination^
since each cultvire had 25 seeds.

Each total-shoot -elongation value (2 and 4, abope)
divided by the corresponding number of seedlings measiired,
gives the average length of shoot for the seeds that
germinated in the culture in question. This quotient
represents the average grov/th per seed in each case,
omitting the seeds that failed to germinate. Finally,
since the time periods were not exactly the same for all

-17-

series, the quotient just mentioned is to be divided by the
exact ntuiiber of hovrrs elapsed since the starting of the
cultures in each case, thus giving the mean hourly rate of
shoot elongation for the given culture. Subtracting the
total elongat ion value for the shorter period (2, above)
from the corresponding value for the lohger period (4, above^
gives a number representing the total shoot elongation for
the last portion (about 24 hours) of the whole culture period.

Each of the six different series (each series
corresponding to one of the six solution types and each
including the seven different temperatures) was repeated
once, excepting in the case of the lowest temperatiH'e, so
that the data obtained refer to the first or second test
for each series, excepting those for 13° C.

• Viability , grov/th rate. and solution composition*
Forty-tv;o tables of data weie obtained from these 6 solu-
tion types, tested at 7 different maintained temperatures.

Only table I, giving the results obtained from the solutions

in this
of type I tested at 31° C, is giv-en/papei; it is presented

as an illustration of the results obtained at the end of

the culture period (3 and 4, alcove.). The two halves of

the table represent the tv; o like tests for the solutions

or sets of salt proportions,
of type I and for 31° C. -^'he solutioni^are designated

by the symbols in the first column, these teiag Repeated fbr the

test as the data are here tshul- ted.
secbnd/ Each rue an hourly rate of shoot elongation is obtained

-B-

TARLE I.
Mean Ilo^irly Shoot J^'lonp;atlcn for Solutlcns of Type 1,

o

Temperature , 51 C

' Plrst Test

Sol.

Total

Ilo.of

No.

elongation
mm.

seedlings

RlSl

1600

22

R1S2

146S

23

R1S3

1153

16

R1S4

1459

19

R1S5

1784

24

R1S6

1179

18

R2S1

1229

20

R2S2

J639

21

R2S3

1026

14

R2S4

900

17

R2S5

1091

18

R3S1

1623

20

R3S2

1545

20

R3S3

1567

20

R3S4

1264

18

R4S1

1269

18

R4S2

1429

20

R4S3

1118

18

R5S1

1360

18

R5S2

1423

18

Mean hourly rate for
period of 114 hours
Actual In terms of
mm. average.

R6S1

Average

1119

16

.64
.56
.63
.67
.65
.58

.54
.58
.64
.46
.53

.71
.68
.69

.62
.63
.54

.66
.69

.61

.64

1.00

.88

.98
1.05X
1.02

.91

.84
.91
1.00
.72
►83

l.llx
l.OBxx
1.08XX
.97

.97

.98
.84

l.OSx
l.OSxx

.95

1.00

TABLE I (Cont.)

-19-

Second Test

Sol.

Total

No. of

No.

elongation
mm. -

seedlings

RlSl

1605

22

R1S2

1889

23

R1S3

1788

21

R1S4

1676

21

R1S5

1423

18

R1S6

1483

18

R2S1

1866

23

R2S2

1802

24

R2S3

1194

16

R2S4

1335

19

S2S5

1568

21

R3S1

1615

22

R5S2

1529

17

R3S3

1776

22

R3S4

1593

20

R4S1

1580

22

R4S2

1703

22

R4S3

1621

19

R5S1

1754

23

R5S2

1716

21

R6S1

1670

21

Average

--

Mean hourly rste for
period of 114 ho\irs
Actual In terms of

TOn.^ average.

.65
.77
.76
.71
.71
.74

.72
.67
.67
.63
.67

.65
.80
.72

.71

.64
.69
.76

.68
.73

.71

.70

.93
l.lOx
1.09X
1.01
1.01
1.06X

1.03X
,96
.96
.90
.96

.93
1 . 14xs:
1 . 03xx
1.01

.91

.99

1.09X

.97
1.04XX

1.00

1.00

-HO-

by dividing the total elongation "by the corresponding

nxunber of seedlings. The 21 hourlj'- rates are averaged
for each test and each late is expressed in terms of the
average of its own test.

Inspection of 1hese sample data brings out
several points genarally aHP arent throughout 'tlie entire
mass of data for all six types and for all tempa: atures
tested. In the first place, no relation is discovered
between the solution composition (indicated by the solution
symbol in each case) and the number of soeds ■ftiat germin-
ated. The percentege of germination was not evidently
influenced by the salt proportions. "For the first test, th^
number of seedlings obtained from 25 seeds ranged from 14 t o
24, for the second test this range is from 16 to '^4, and the
table shows very little agreement between the numbers of
seedlings obtained with the same solution in the two like
tests. This state of affairs holds for all the series in
about the same way, so that it became apparent tlB t the
germination percentage could not be considered .on th e bas is
of this study, as influenced ly the salt proportionE . It is
also true that this percentage was not apperently influenced
by the temperature. (Of course, germination was more rapid
with some temperatures than v;ith others; reference is here
made merely to the number of seeds that had

-21-

germinated after about 110 hoiirs.) The differences in the
ntunber of seedlings produced from the 25 seeds \iere appar-
ently largely due to internal differences in the seeds
themselves. At any rate, the individual variation among
the several groups of 25 seeds xms apparently greater than
any possible differences in viability that may have been
related to salt proportions or temperature; if there v/ere
any stxch differences they were masked by individual
variation. VJitli these points in mind, v;e may dismiss the
topic of percentage of germination as a characteristic of
these seeds that was not appreciably influenced by either
the kind of solution used, or the temperature eraployedo
In this connection, it may be mentioned that all the solu-
tions used v;ere relatively very dilute so that there could
have been no significant influence exerted in the osmotic
way.

Tnxning to the mean hourly rates of shoot
elongation for the entire culture period, as illustrated

by the data of table I, the first test of these solutions

o
v/lth a temperature of 31 C. gave an average rate of .64 ram.

and the second test gave an average rate of .70 mm. In the

first test, the mean rates ranged from 28 per cent below

the average (relative rate,. 72 ), to 11 per cent above it

(relative rate, 1.11), thus showing a total range of 39 per

cent of the average. The solutions that gave mean rates

above the average in this first test might be accounted as

better than others, but a comparison of the relative rate
values for the two tests brings out the fact that some
solutions showing mean rates above the average in one test
showed rates below it in the other test. The solutions that
gave mean rates more than 2 per cent above the average rate
are marked v^ith an X at the extreme right of table I, and
only three of them (marked with a double X) are thus designated
for both tests. These three sol^itlons (R3S2, R3S2'/ and R5S2)
might be considered as definitely better than the others of
this type and temperatiore, btit there is no app&rent- relation
between this apparent "goodness" of the solutions and the
corresponding salt proportions. T\,o of these ^^are in rov; 3
and the other is in row 5 of the triangular diagram, so that
they are not adjacent as to the potassi^um salt. Tv/o are
second in the row, the other being third, so that the former
two have tv7o-eighths of their salt molec\ales in the form of
the calcivim salt, and the latter has three-eighths in this
form. The intervening solution with two-eighths of its salt
molecules in the form of the calcium salt (R4G2) gave a value
somewhat below the relative value 1.00 in both tests. Finally,
one of these exceptionally "good" solutions has three-eighths
of its total niomber of salt molecules in the form of the
magnesium salt, another has tv/o-eighths. and the third has but
one-eighth in that form. It therefore seems that the except-
ional "goodness" of these three solutions is not clearly
T^elated to the salt proportions employed.

-23-

A thorou{ih study of all the series of cists' leads
to a similai' conclusj.on for the other series. i:0 consistent
evidence was an^nivhere clearly discernable bet?;een salt pro-
portions and the mean hourly grov;th rate for the entire culture
period. Several suggestions of certain relations between grovith
and the composition of the nutrient solutions were encountered,
^ 'but careful study of the nuriericel data end the extent of
the variability encountered with this seed leads to the con-
clusion stated above. This conclusion of course applies only
to the tests here considered, dealing with the very first

(6)

In a preliminary paper/ the author reported on

one of these suggestions, interpreting the datfi to show that
nutrient solutions having a relatively high potassium-ion
proportion were / relatively poorer growth media for these
wheat seedlings at high temperatures than they were at low
temperatures; and that, at low temperatures, nuti'ient
solutions high in potassium-ion proportion v;ere relatively
better for growth than they were at high tem.peratujpes . It
v/as stibsequently found that a more rigid method for defining
the "best" solutions (as shovm infc^ble II of this paper)
resulted in the elimination of some of the solutions reported
as "best" in the preliminary paper. The suggestion here con-
sidered has proved to be of value, however, and it has led to
further and more comprehensive experimentation along this line,
but v/ith longer grovfth periods. Selected solutions of the
a-ix types were tested, each one in a set of at least ten like

-24-

phases of 2rov/th_,v,'ith very dilute solutions and with the
variaVile seed usei. For the short ctilture period here
employed, the material contained in the seeds may have
played no inconsiderable part in determining the results,
preventing any influence by the salt contents of the very
weak solutions used, ^'i'ithout doubt, solutions of higher total
concentration vrould have shovm considerable differences in
grov/th with regard to salt proportions, and probably the vieak
solutions here used would have shown definite salt influences
with later phases of grov/th or with less variable seed.

cultiires (for the statistical interpretation of the data) and
with both a high and a low temperature. Definite solution-
grov/th effects and solution-temperature-growth effects were
obtained, which support the suggestion mentioned above. Since
the culture periods for these later experiments were much longer
than those for the tests of this study, thus including later
growth phases, the later results are to be reported in another
paper. The present report deals only with the tests described
in the text. For the preliminary paper, see: Gericke, V/.P.
Influences of temperature on the relations betv^een nutrient salt
proportions and the early growth of v/heat. Amer. Jour. Eot.
8:59-62. 1921.

■ Because of the conclusions just ststed, it is vin-

necessary to present the detailed ;];roT;th deta in thif=! pnper,

o
and the data for 31 C. and Tjpe I_j f or the whole culture

period (table I) may svifflce as an Illustration. The most
Interesting points of the omitted tables for the entire culture
period are presented, hov/ever, in tables II and III, in sum-
marized form. Table II gives a list of apparently best solut-
ions for shoot elongation for each temperature (excepting the
lov/est, for -.vhich only one single test was made) and for each
solution type. Tlie solutions listed include only those which
agree^ for both tests in giving mean hourly rates (for the
whole culture period) that are more than 2 percent above the
average for the series in which they occur, and for v/hich the
difference between the corresponding rates for the two tests
is .ll ram QX" less. Of the three solutions marked with s double
X in table I, as giving grov7th values more than 2 per cent
above the average for their series in both tests, the first
(R3S2) is oraitted from table II because the value for the first
test is .68 ram. and that for the second is .80 ram., the differ-
ence being more than .11 mm. By this somev.'hat arbitrary scheme
those solutions are listed as apparently best that showed fair
agreement in the actual average hourly growth rates of the tv/o
tests and that showed growth rates, for both tests, more than
2 per cent above the series average.

Three grov/th values are given opposite each culture
symbol in table Iljthese being separated by colons; the first

-26-

value is that from the first test, the lest is that from the

second test, and the second is the average of the first and

o
last. Thus, for type I, 31 C (see also table I), culture

R5S2 gave a mean hourly rate of shoot elongation of .69 ram.

by the first test and .73 ram. by the second test, the average

for both tests being .71 mm. V/hen no data are given in table

II for any temperature and type this means that no solutions

fulfill the requirements here taken as defining the best

soliitions.

TABLE II.
■^TPAPE'^^TI?''
Smiiv'ARY QP/EE^T 'cultures FOR SHOOT-GROWTH, ENTIRE PERIOD.

(See text for explanation.)

-27-

Sol.
type

II.

III.

V.

VI.

Ternp .
35 °C.

R3S2, 57:60: 64
R3S5,68:68:68

^

R2S5,58:i
R4Sl,6i:"6i::60
R4S5 , 52 : 56 : 59

R1S5, 60:58:55
R2S2,64:64:64
R5S4, 70:66. 61

IV. R1S3, 65:65:64

R1S5, 62:60:57
R2S5, 62:62:61

R2S1,59:61:62
R2S2, 54:58:61
R4S2, 60:61:61
R5S2, 58:57:55

R5S1,52:56:60
R5S2,56:59:61
R6S1,54:53:52

Temp .
31°C.

R5S2, 69:71:73

R1S3,72:74:76

R1S4,77:80:82

RlS5,72:fe^:7d-tVs

R2S1,69:73:.76

R1S1,78:74:70
R1S2,77:75:72
R1S3,77:75:73
R1S4,76:75:74
R1S5, 70:72:73
K3S3, 78: 76:73

RlSl, 75:79:83
R2S1,78:78:78
R2S5, 76:75:74
R5S2,7o:77:81

R1S2, 76:71:66
RlS3,7g:75:77
R1S4,73:75:77
R2S1, 74: 74:75
R3S2, 75:71:67
R4S2,69:69:68

RlSl, 77:71:65
R1S3,78:73:68
R3S1, 79:75:70

Temp.
26PC.

R1S3,71: 72:73
R1S4, 71:73:74
R3S2, 70:71:71
R4S1,72:72:72
R4S2,70:74:^77_

R1S2, 70:75:75

R1S3, 71:73:75
R1S4,80: 80:79
R2S1,84:77:70

R1S4,78:75:69
R1S5, 78:75:69
R2S1,82:86:89
R2S2,77:80:82

R1S4,87:86;84
R1S5,94:69:84

R1S4,79:74:69

R1S3,76:75:74
R3S4,76:73:69
R4S2,77:76:74

-28-

TABLE II. (Cont. )

Sol. Temp Temp. Temp,

type. 2^0. 21° C. 17° C.

I. R1S4, 56:58:60 R3S1,46 :49 :52 R4S3,22 :25 :27

R4S2, 46:49:52 R5S1, 21:25:29

II. R1S5, 44:40:36 R4S3, 28:25:21

R4S1,46:42:57 R5S2,26:24:22
R5S2, 46:42:37
R6S1,47: 42:37

III. R2S4, 66:62:58 R2S5,49 :44:39 R2S2, 34:30:26
R2S5, 68:64:59 R3S4,29 :27:25

R5S1, 32:30:27

IV. R1S2, 56:58:60 R1S3,39 :42:44 R5S1,25 :26 :26

(^_lS5a.62j61:59^ R4S2,41:43:44 R5S2,25:25:26
R1S4,55:57:59])
R2S1,61:59:57
R2S2,56:58:60

V. R1S4, 77:72:67 R1S3,63 :58:58 R5S2, 44:39 :54

R4S2,71:67:62 R2S1, 59 : 58:57

R5S1,59:57:55

VI. R1S4, 65:61:56 R5S1, 45:45:44 R3S4, 23:27:30

R4S2,63:62:60 R5S2,48:49 :49 R4S3,23:27 :30

R5S1, 64:63:62 R6S1, 48:48:48 R5S1, 24:27:30
R6S1,60:60:59 R6S1,26:28:30

-29-

Table III is somewhat like table II, but it presents the
appacnptly poorest solutions for shoot grov/th instead of the appa-
rently best ones. '-The soliitions shovrn in this list are those
whose grov;th values are among the four lov^est of their
respective series, for both tests, and for which the growth

values for the two like tests show differences _o-f .11 mm^w
js^ le&i=i« Otherwise, the notation follows the scheme of
table II*

-30-

TABLE III.

SUl^' i\RY OP/fUC)REsVcULTURES FOR SHOOT-GRO'^-TH, ENTIRE PERIOD.
(See text for explanation.)

sol. Terap. Terap. Tenp.

type. 350 C. 31° G. 28° C.

I R1S1,44:48:53

II R1S2, 38:38:40 RlSl, 57:54:52 R2S4, 55:51:48
R3S1, 41:44:48 R4S5, 55:56 :57 R2S5, 55:51 :47

R3S4,57:53:49
R5S1,46:51:46

III R5S2,42:41:41 R3S2,61 :58:55 R3S2,53:54:56

R4S2, 49:53:58 R5S2, 62:58:54
R4S3,52:54:55
R6S1,60:62:64

IV R3S4,62:60:58 R2S5 ,53:56:59

R5S1, 60:59:58 R5S2, 53:52:51

V R1S5,38:41:45 R5S2,47 :46 :46 R6S1,63:60:57

VI R1S6, 48:44: 40 R2S1,63 :60:58 R1S5,57:57 :57

R2S2,66:64:61

TABLE III (Cont.)

-31-

Sol.

t^rpe

Tenp.
25° C.

Temp.
21° G

Temp .
17° C.

R2S2,45:48:51

II.

R4S3,50:46:42

III. R4S2,55:49:46

R6S1,47:46:46

IV. R2S4, 48:49:50

R5S2 , 48 : 46 : 44

V. R5S2,50:49:48

VI. R1S5, 49:48:47
R1S6,55:50:46

R2S2,36:40:44
R3S3,^'5-:42:41:
R3S4,36:40:44
R4S3, 35:40:44

R2S3,33:31:29
R3S2, 37:32:28

R2S2, 34:36:39
R2S3,32:35:38
R3S3, 34:35:36
R5S2,33:35:37
R6S1, 33:34:36

R3S4,44:42:41

R2S3,34:35:36
R2S4, 38:39:40
R3S2,33:35:38

R1S2, 18:22:25
R1S3,18:20:22
R1S4, 19:21:22
R2S2,17:21:25

R1S4,22:20:18
R3S1,22:20:18

R1S3,26:23:20
R4S3,20:20:20
R5S2,21:19:18

R1S6, 20:20:21
R2S1,20:19:19
R2S3,20:19:19
R2S4,18:18:19
R3S2, 18:19:20
R3S4,18:19:19

R1S1,19:20:22

-32-

Tables II rnd III place on record, for use in
f-iittire studies and comparisons, the sets of salt propor-
tions that gave, respectively, the best and poorest grov/th
rates for each solution type and temperature, for about 110
hours from the beginning of germination. If the seed had
shov/n less variability, it may be that such summaries as
these might have shov/n some clear and tmmistakable relations
between the make-up of the solution and its physiological
effect. As has been said, perhaps because of the extent of
the unexplained variability encountered in this study. a con-
sideration of the data here presented leads to the conclusion
that no clear and consistent evidence is here given for hold-
ing any solution better than any other of the ones tested,
for these temperatures, for this seed, for the length of the
test period, and for the other details of these tests as
reported.

It seems somei7hat inconsistent to m.ake mention, on
the one hand, of the "apparently best" and the "apparently
poorest" solutions/ in each group^thereby suggesting that
differences are apparent and related to the chemical proper-
ties or salt proportions of the solutions, and, on the other
hand, to state that all the solutions tested are to be con-
sidered as essentially alike v/ith respect to germination and
early growth of the v/heat used. This seeming inconsistency
disappears, however, upon careful consideration.

-33-

The "apparently best" and "aioparently poorest" solutions
■shown in tables II and III are clearly the ones that did
give, individually and empirically, respectively h^%iyer^ and
3-ower crowth rates than the averages in the several series.
One group of solutions (tablell) v^ere poor, by actual test.
Had the^^ v.'hole series of 126 solutions been selected at
random, without reference to the physico-chemical scheme of
the triangular diagram, then the list of good solutions v/ould
have to be taken at its face value, as showing v/hich solutions
had been found best by test. B\it the solutions of this study
were not selected at random, they represent a certain definite
series of different sets of salt proportions and different
salts, '.'.'ithin the limits set by the chosen total concentration
and by the nine salts used, the series is so selected as to be
equally distributed throughout the entire range of possibilities.
They are somewhat like a set of soil samples secured one from
each of a number of stations frequently and equally spaced
over a broad terrain comprising many kinds of soil. This being
the case, it follows that evidence for any significant influence
exerted by the makeup of any given solution should be shown not
only by that particular solution itself btit also by the solutions
adjacent to it on the triangular diagram. A study of the salt
proportions of the "apparently best" solutions and of the growth
rates given by the adjacent solutions fails generally, in the
present study, to bring forth any evidence that one set of salt

proportions proved definitely better than another for the
same solution type, or that one type ^i-ui^ed— e«Ht clearly
better, for any set of salt proportions than another. It
is the logical relations betv^een the "apparently best" or
"apparently poorest" solutions snd the other solutions, as
these relations are visualized by means of the diagrams,
that finally leads to the conclusion that their "goodness"
or "poorness" is only apparent and is not clearly shown as
related to salts and salt proportions. There is no doubt
at all that the "apparently best" solutions were actually
the best in these tests, but the logically necessary
collateral evidence is uniformly lacking to show this
"goodness" as related to salts and salt proportions.

-34-

Grov/th-Teinpera ture Relations «

The considerations presented in the preceding
paper led to the suggestion that all the mean grov/th rates
for each separate series might be averaged to give an
average growth rate for the given test and series, that
these averages for tv;o corresponding tests vfith the same
temperature might be themselves averaged to give a single
value representing the growth rate for the given temperat^^re
and solution t^^pe, and that all the six type averages might
be averaged for each temperature to give a single growth
index for each temperature considered. The logical basis
for this mode of treatment may be stated as follows: Since
the data at hand do not establish any relation between
solution composition and grovfth rate for any temperature,
all solutions may be treated as though they were physiolog-
ically alike, within the limits of precision set by the in-
nate variability of the seed used, etc.

An inspection of the 42 tables obtained for the 6
solution types tested v;ith 7 different ns.intained temperatures/
for the entire culture period/ as well as for the tvfo partial
periods (of nhich table I is an example), brought out very
clearly the fact that the temperature influence on growth rate
was pronounced and consistent, in spite of the great individual
variations of the seedlings and quite v;ithout regard to the
rasBceup of the solutions used. In the following pages the

-35-

temperature-growth relations shovm by these tests will be
considered/, 8 s though the cultures had all been carried out
with exactly the same medium. The average growth index for
each of the seven temperatures, was calculated treating all
of the 126 solutions as if they had been quite the same, and
these temperature-growth indices v/ere employed as the basis
for a study of the relation of temperature to shoot grov/th 0^
shovm in these tests.

-36-

Temperature Relations f oi' the Entire Culture
Period (About 110 Hours) . •

Table IV presents the series, type, and
temperature averages for the entire culture period, being
a svimnai^jr of the temperatvire relations shown by the 42
tables, of which Table I is a sample and f rom wh Ich tables
II and III v/ere derived* In each case the minimum and
maximum are given, es well as the average, the tiiree
values (in hundredths millimeter per hour of shoot growth,
for periods ranging from 108 to 114 hours) being given
consecutively, separated by colons, in the serial order:
minimum, a v e r ag; e , ma x imum » For example, referring to
table I, the average for all solutions of- the first test
is .64 mm., the mlnlm.um is .53 mm., and the maximxHti is
.71 mm. Hence, the summary of the first part of table I
may be represented by the formula 53:64:71. In like
manner, the summary for the second part of table I is
63:70:77. The averages fcr the several pairs of like
tests (excepting for the lov/est temperatiJire , for vfhich only
One testwas made) are shown in the next to the lest coliimn
of table IV and the grand average for each temperatvire
is given in the last col wan. The grand averages bring
out very clearly the facts that the highest rates of shoot
elongation were obtained with the maj.ntained temperatures
28 and 31 (tlie values being about alike), that temperatures

-37-

2 5° and 35° gave retes that aro markedly lov/er than those
for 28° and 31°, and that temper at vires 21°, 17° and 13°
gave still lower rates, these being progressively lov;er
with lov/er temperatiires. These grand averages will
receive attention below.

-38-

TABLE IV.
SUMMARY OP AVERAGE r.ATE? OF SHOOT ELONGATION FOR THE EN-
TIRE CULTURE lERIOD AND FOR ALL SERIES.

Tem-

Solu-

Length of

Min. Ave.

end Max.

Ave. of

Grand

per-

tion

per

led

hourly

rate*

1st &

Ave. for

atiAT'e

type

ft

\, •

ra . ]

2nd

given

1st

2nd

1st test

2nd test

tests

temp.

test

test

.^Imm.

.Olmm.

.Olm .

.01 TSSK.

hrs.

hrs.

35°

I

114

112

38:53:70

47:61:70

57

II

108

110

23:47:61

40:51:60

49

III

110

112

25:57:71

37:52:61

55

IV

112

110

47:60:78

37:51:64

56

53

V

108

114

36:49:59

34:52:67

51

VI

108

110

43:51:59

41:48:65

49

31°

j^H^

114

112

50:64:71

63:70:77

67

II

108

110

50:63:77

52:67:82

65

III

110

112

49:69:78

53:67:78

68

IV

112

110

54:68:78

52:68:83

68

66

V

108

114

47:66:76

46:64:77

65

VI

108

110

63:74:85

54:62:70

68

280

I

114

112

52:64:73

55:68:78

66

II

108

110

55:63:84

45:58:79

61

III

110

112

53:70:86

49:63:89

67

IV

112

110

52:64:94

47:67:84

66

66

V

108

114

61:74:98

55:67:76

71

VI

108

110

57:70:84

50:63:75

67

25°

I

114

112

43:50:61

48:57:66

55

II

108

110

48:54:65

39:45:49

50

III

110

112

43:59:68

43 : 53 : 62

55

IV

112

110

48:53:62

41:54:60

54

55

V

108

114

50:67:79

44:57:67

62

VI

108

110

48:58:65

38:52:62

54

tj

^■The first value given is the ninimiun, the second
is the average, and the last the maximum.

^'■"'Detailed data for 31^, t^^^pe I, are given in
Table I.

TABLE IV (Cont.)

39-

Tem-

Solu-

Length of

Min., Ave.

and Max.

Ave. of

Grand

per-

tion

period

hourly

rate

1st &

Ave. for

atvire

type

hours .

i .01 iWtt*^)

2nd

given

1st

2nd

1st test

;jnd test

tests

temp .

test

test

■*•/-,■ .

■ --

,, ' -O' rt-

( .01 ram. )

210

I

114

112

32:38:46

37:46:52

42

II

108

110

33:41:47

27:33:39

37

III

110

112

40 : 48 : 53

22:34:42

41

IV

112

110

32:36:42

36:43:49

40

42

V

108

114

44:57:67

55:46:57

51

VI

108

110

33:44:70

22 : 42 : 52

43

170

I

114

112

14:20:23

21:25:29

22

II

108

110

19:24:30

13 : 19 : 22

22

III

110

112

20:28:35

18:23:27

26

IV

112

110

12:20:25

19 : 23 : 26

21

25

V

108

114

32:39:47

17:25:33

32

VI

108

110

16:21:26

20:25:30

23

150

I

II
III

114
108
110

04:06:07
04:07:20
03 : 04 : 06

■-'•■

IV

112

04:06:08

07

V

108

06:10:13

VI

108

04:06:07

-40-

Tempersture Relations of Ciiltixres in Distilled

Vjeter.

A series of cultures vfas carried out with

distilled water instead of nutrient solutions, and the

obtalnecl
mean hovirly rates of shoot el6ngatlon/^or a 110 hour

period and for the seven different maintained temperatvires,

are given in table V. Corresponding data for the nutrient

solution cultures are given in tha-t- table for comparison.

TABLE V.

-41

TEMPERATUKFJ REL A TIONS OP SHOOT ELONGATION FOR DISTILLED
WATER CULTUiES /iND NUTRI5NT SOLUTION CULTURES, FOR
ABOUT 110 HOURS PROM THE BEGINNING OF GERMIN-
ATION, VALUES BEING MEAN HOURLY RATES

IN TEPITS OF nUIiriP.KDTHF OF A MIIIIMETEE.

Maintained Distilled

Nutrient Solution Cultures

iperatuj

-■e water

cultures.

Highest
rate
obtained
(See Table
III.)

Lowest
rate

obtained
(See Table
III.)

Grand Average
for given tem-
perature.
(See Table IV.)

350

30

68

38

53

31^

33

80

46

67 ^

•

280

36

86

51

66

25°

31

72

46

55

210

22

58

13

42

17°

16

30

18

25

13°

7

13

3

7

-42-

The rates for the distilled water cnltures
show the same general temperatiire relations as those
shown tj fj) the highest rates, (2) the lowest rates

and (3) the grand averages, for the nutrient solution

o o
cultures. in all cases the rates for 28 and 31 are

the highest and about alike, those for 25 and 35° are

lower and about alike, those -^or 21°, 17° and 13° ^^^

progresively stilllower.

The distilled-water value is markedly lov;er,

however, fin every case excepting that for 13 ), than

is the corresponding highest rate or the corresponding

grand average value from the nutrient solution cultures.

Furthermore, the distilled-water value is somewhat lower

than even the lowest rat§ from the nutrient solution

cultures in all cases, excepting that for 13°. It appears

from table ^^ that the cultures with distilled water generally

gave mean ratesfebout half as great as th^ corresponding rates

obtained with nutrlnnt solutions, -js- tlie lov-est temperature

tested (13), the distilled-water cultures gave a rate just

equal to the grand average for this temperature with nutrient

solutions. All of the solutions tested were of about the

same osmotic value (eoiuivalent to about 0.1 atm. of osmotic

pressure), so that the one feature by v;hich all soluions

agreed among themselves and yet differed from distilled

water is with regard to osmotic value. The solutions differed

-43-

from water, and agreed among themselves in that they all
contained the six kinds of Inorganic atoms or atomic groups
(potential ions) known to he needed for plants in general,

l3ut as has heen made clear -- they did not contain these

atoms and groups in the same proportions. It is clear that
the presence of a slifht osmotic value due to the salts used,
or the presence of a small amount of the essential atoms and
atomic groups in the solutions, greatly improved the water for
the growth phases here dealt with. Since the solutions differed
markedly in salt and salt proportion and at the same time were
all essentially alike In their influence; on the plantlets, it
seems probable that any lower total concentration of any of
these solutions (between 0.1 atm, of potential osmotic press\ire
--the solution concentration used-- as In the case of water)
would have shown growth rates more like those secured with
water than like those obtained from solution actxially tested,
but still alike among themselves for the solution series. 1$
is practically certain that if the solution concentration had
been greater f'wlth an osmotic value greater than 0.1 atm. of i
potential pressxire)^ they would have shown some relations •
between shoot growth and salt composition, even with seed as
variable as that here used, ""ith what total concentration
value this might occur is of course not predictable without
experimentation.

TO the conclusions thus far reached may now be
added these, that all these solutions used are much better

-44-

suited to the germination and growth of this wheat than is
distilled water. It is safe to state that distilled water
is not at all suitable for a germination medium when solution
cultures are being prepared, unless sickly plantlets are
required.

The unsuitability of distilled water for seed
germination, etc., has been emphasize^ and discussed by-
several authors'!' )and the reason for this need not be dealt
with here. It may be mentioned, however, that the water of
the Johns Hopkins Laboratory of Plant Physiology is generally
free from direct toxic influences ( due to Impurities V and
that the injurious effect here shown was probably due to out-
ward diffusion of substances from the seed and seedlings.
This conclusion follows the discussion o"^ True and Bartlettfg)
and True (9i), for somewhat similar experiments.

(7) A rather complete resume of the literature on
the physiological nroperties of distilled water, up to the
time of its publication, is given in the following paper:
Livingston, 3.E., et al. Further studies on the properties
of unproductive ■ soTTs. - U.S. Dept. Agrio., 3iir. Soils, sul.
7)6,1307, see also,. me and Bartlett, cited just below.

(8) True, Rodney H. , and I>i-rtlett ,H.H. Absorption

and excretion of salts by roots, as influenced by concentration
and composition of culture solutions. Tj,s,T)ept.Agric. , Bur.
Plant Ind. Bui. 231. 1912.

f9) True, ?.H. Harmful action of distilled water.
Amer. Jour. Bot. Yol. 1:255-273. 1914.

-45-

Tpniperature Relations for the last 24 Hours
of the C\ilt\ire Period*

Table VI presents a siminary of the grov;th-

temperature data for all series, for the last 24 hours.

It v/as realized that the data for the entire culture period

(table IV) refer to actual shoot elongation only In part;

in the earlier part of the cultm-e period shoot elongation

had not yet begxin. In a very general v;ay, the data for the

last 24 hours may be regarded as referring primarll^r to

seedling enlargement, v/hlle those for the first portion of

the
the period refer largely to/preliminary processes generally

considered as seed germlnatlonc -i>t3tt^tr3res-s-„ it is for this

reason that the average rates shown in table VI are so

much larger than those shov;n In table IV »

The notation of table VI is self-explanatory,

being somewhat simpler than that of table IV.

-46-

TABLE VI. .
SUMMARY OP AVERAGE DATA ON SHOOT EL,0NGATION FOR THE lAST
24 HOURS OP THE CULTURE PERIOD FOR ALL SERIES.

Tem-

Solu-

Mean Hourly Rate

Aveggge

Grand ave.

pera-

tion

l- • • •■-

1st ; 2nd

far given

ture .

t^^pe

1st test

2nc test

tests .

temperature

-

.Olmm,

.Olnm.

' .Olmns .

[ .Olmni, ... )

35°

I

118

126

122

II

121

137

129

III

123

118

121

IV

134

114

124

124

V

128

131

129

VI

121

121

121

31°

I

143

149

146

II

148

165

152

III

156

140

148

IV

162

145

153

153

V

153

158

155

VI

165

156

161

280

I

151

149

150

n

158

158

158

III

160

156

158

IV

154

152

153

157

V

166

158

162

VI

162

160

161

25°

I

140

140

140

II

135

137

136

III

138

124

131

IV

140

124

132

137

V

153

141

147

VI

130

138

134

21'^

I

104

126

115

II

126

110

118

in

101

96

99

IV

108

101

105

112

V

120

115

118

VI

104

123

114

-47-

TABIF: VI (Cont.)

•

Tem- Solu- Mean Hotjrly Rate Average Grand ave

pera- tion v* • '- < •) Ist^S 2nd per given

ture . type 1st test Snc. test tests. temperature

.Olran. .OlmK. ( .Olmia, .) i .Olnm.

170 I 72

II 90

III 85

IV 75 -- 75 82

V 100
VI

13° I 27

n 31

III 24

IV 26 — 26 30

V 40

VI 27

Rate

Average
lst^£^2nd

:.)

test

tests.

OlmK.

( .Olmia, . )

'

84

78

91

90

75

79

—

75

—

100

87

87

,M mm

27

— —

31

- -

24

— -

26

--

40

•.-

27

-48-

Temper at m^e Relations £b r the I'^lr st Part
(/About 86 Hours) of the Culture Period.

Table VII presents a sijminary of the growth-
ten^erature data for all series for that part of the
entire culture period that preceded the last 24 hours.
The notation is the same as that for table VI. Ko data
are available for the lowest temperature (13°C.),

-49-

TABLE VII.
SUMMARY OF AV^-J^AGE DATA ON SHOOT ELONGATION FOR THE
FIRST PART (ABOUT 86 HOURS) OF THE^ CULTURE PERIOD

FOR ALL SERITiS.

Tem-

Solu-

Mean Hourly Rate

Average
Ist?^^ 2nd

Grand Ave.

pera-

tion

.

• • •• /

^0-

: given

ture.

tj'pe

1st test

2nt test

tests.

temperature

.Olmm.

.Olmn.

, .Olrmri.'.i, )

{•

.OlBnnvji. )

35°

I

35

41

38

II

27

25

26

III

38

34

36

IV

36

32

34

31

V

26

27

27

VI

28

26

27

31°

I

40

47

44

II

40

34

237

III

44

47

46

IV

43

44

44

42

V

38

37

38

VI

46

37

42

28°

I

41

46

44

II

34

53

34

III

40

36

38

IV

38

40

39

40

V

44

40

42

VI

41

37

39

25°

I

30

33

32

II

31

23

27

III

38

33

36

IV

31

33

32

?.z

V

58

32

35

VT

35

28

32

21°

I

20

23

22

II

17

13

15

III

29

29

29

IV

18

23

21

S3

V

33

23

28

VI

24

20

22

TABLE VII. (Cent.)

-50-

Tem-

Solu-

Mean Hoti

rly Rate

1st - 2nd

pera-

tion

• -

^

- • ]

ture.

tirpe

1st test

2nc test

tests.

• Olmni.

.Olcm.

( .Olrnin&iii. ;

17°

1

7

9

8

n

5

-

5

III

12

9

11

IV

8

-

8

V

16

-

16

VI

9

-

9

Grand Ave.

fo-' given
temperature
( •Olnm Wi* /

9.5

-51-

The general temperatui^ relations shov/n in
tables IV and VI are seen to hold also for table VII,
The mean hourly rates given in the lact table are, of
course, much lov/er than the corresponding ones for the
last 24 hours (table Vl)and they are notably lower than
those far the entire period (table IV). The next section
will be devoted to a comparison of these three sets of
growth- temperature data by means of graphs.

-S8-

GRAPHS OF TIIE GRO-,?TH- rEMPERATTJEE RELATIONS.

It has iDeen stated above that all three series of
grand averagesCfor the whole period, for the last 24 hovirs,
and for the first part of the period) agree in showing the
highest growth rates for the maintained temperatures, 28
and 31 , and that the average rates for these two tempera-
tures are nearly alike in all three cases. Referring to

tables TV, yj and VII for to the graphs of fij. 1), it is

9
seen that the rate for 31 is 2.5 per cent lower than that

for 28 , for the last 24 hours of the culture period. ?or

the entire period the rate for 28 is 1.5 per cent lower

than that for 31 and for the first part of the culture per-

f^ 0

iod the rate for 28 is 4.7 per cent lower than th^^t for 31 .

It is probably safe to regard these dif''erences as insignifi-
cant, considering the general nature of the entire study, and
to state thst the data here considered indicate that the op-
timum temperature for the germination of these se"ds and the

n 0
early growth of the seeJling shoots lies between 28 and 3l' .

/ growth-temperature graph was prepared for each of

the three sets of grand averages and a study of these graphs

will bring out some additional information. The three graphs

are shown in figure 1. The actual values are shov;n by the

circles and the lines represent smoothed graphs drawn to fit

the distribution of the circles in each case, ""hey may be

taken as indicating a close approximation to the inclications

LEGEND FOR FIGURE 1

Figure 1. flrapha showing mean hourly rates of shoot

elongation in solution cilltures, for tne entire culture period

(about 1 10 hours) * for the last 24 hours of the period, and

for the first part of the period (about 86 hours) jand ■ Iso
in di st i 1 1 ed - wat er cultures for the entire period, as these

rates are related to itaaintained temperature. Temperatures are

shown by abscissas and growth rates by ordinates.

' 1 1 1 1 ! '

•

r-l
-■1

H

r
D

o
o

no

u •

U

b5

f-( ^ . /

r- ' •r' - ;

o ^J± /

O 4J '

i / :

_1 A "1

1

O

a'

tt3( !<|J

o
a-

!

rt

__£

f 1 ' ' n r "

0

H

i

._■ 1 — ' r O

\ ^+Httt|—

-W4- . ^ T' ' 1 i ■ l-^^O if

+5

Cvj

r- \ . ! ; TX«n \

1

1 1 1

' ; r : \ i " ■' ii

-Lite ' '\

o

c^

j

— , . , .... .. '^

CVi

1

.

. \

c

' \ \

o

\ \

c

^ \

i- - \

-

_ \ 'I

_::_ _:^» _ _ ^

\ (W '

u;.

r>:

\

C^I

i 1

V

i 1

1

L

s^

_. A-- - -

VI'

^^

\

».^

X

1

3 i

1

i

L,

%

._ _S__ __^

\

\

C -.

V 1 1

1

5_ 1^ '

-

\

_:_ _ : :.s;

\
\

Cv:

^

: " :s" __" "I

^

■— \4t

1 ■ 1 i i ■! 1 U- 1 ! f*,

-4*-l- "^

^"

1 1

-1v-

: 4 ■ 1 ^ .. _ ^^ :

' L

\ o

[ 1 1 1 1 1 1 1 \

\ O

! L i JJ iii L _ _. _ _\

. 1 1 . 1 , . : . 1 , IV M |1JJ_J

\ W

1 ■

\

\ ', ^

1

\ , 8.

1

^

\ H

"" , 1 ^

1

\

- \

cd MM!!! ^

1 i

^ 1 ! 1 1 1 1 1

\ "^

C5

\ \

(-1

I ^ ^

(^ WG>

±

T"1 iTTi

I 1

:

' \ ■ ^

\

\ o

\ Xi<

1

\

j

\

\

-^^-!!ir nn ■ — ?-

\ ^^

I ■ : 1 : 1 : : 1 ! 1 ML, i 1 1 irrf:-

C

«J ' 1 ; , 1 « 3 1

' '' "^ :-l-i -l'

, ^ ' '-— - '^1'^ - 1 :

: ;<' -2: : : t>

o

.:!(}...!. ' ■ 1 M

rii

h , , rfi i ; ; 1 i i :!?::: . 1 1 im: xi

iTr I rrn n T- - -r

-rs-

of the data in each case. A similar graph for the distilled
water cultures, entire period (table v), is also shown in figurei.

The graphs'', ettfestantiate the conclusion that the op-
timal temperature for these tests lay between 28 and 31 ,
almost surely not above 31° nor below 28 . Furthermore, the
form of the curve indicates that the optimum temperature in
every case lies about midway between the two limiting temp-
eratures just mentioned. It may, therefore, be stated that
the optimum temperature for these wheat seeds, for the periods

considered, for the array of solutions used in these studies,

o o
ai?d also for distilled water, surely lies between 28 and 31 ,

with the probability that it is between 29° ana 30°.

m the preparation of wheat seedlings for water

culture experiments (if the most rapid shoot elongation is

desired 1, it is recommended that a temperature betwe-'-n 29 and

30° be employed, and that if the temperature is not maintained,

its fluctuation should not greatly exceed the range between

o 0
28 and 31 . "t must of course be borne in mind that this re-

comraendationis basea on "cnese pari/j.ou±ai vcifciob. Other tempera-
ture relations may well hold for other lots of wheat seed or
for other media than the series here used. It is especially
worthy of note that these sane sets of salts and salt
proportions ( or any one o^ them ) might exhibit

significantly different temperature relations if employed
with suitable concentration higher than the one \ised. V/ith

A

lower total concentrations than the one used, the temperature-
growth relations may be expected to show about the same temperature
optimtjra as the one shown by the three solixtion graphs of figure
I, since the distilled-water graph for the yfentire period/ agrees
v/ith the others in this respect. V/ith sufficiently different
total concentrations from those tested - either weaker or stronger

- the details of graph curvature would probably be significantly
different from those for the solvition graphs shown in figure I.
With sufficiently higher total concentrations even the temperature
optlmura might be different from the one here indicated, and, -
as has been noted - the different sets of salts and salt propor-
tions tested in this study wotild then probably shov; marked dif-
ferences among themselves, so that they could not all be treated
as alike.

Attention should be called to the fact that the recon-
mendation just stated may introduce a modification in the "Plan
for Cooperative Research". On page 15 of that publication, it is

recommended that the temperature used for seed germination should

^ o o

be 25 - 26 . If the most rapid shoot elongation is desired, the

higher temperature range here recommended should surely be u.sed,
when the other influential conditions are similar ito the ones here
tested. But it m.ay hot alv/ays be desirable, in preparing seedlings
for water cultures, to secure the most rapid development of shoots.

Before leaving the consideration of the temperature
relations shovm by the graphs of figure 1, attention may be called

-to the fact that ell four graphs are relatively fl?t in
the region of the optimvim temperature range, end that the
solixtion graphs together indicate that the grovvth-temperatitre
graph tends to become less flat in this region as the seed-
lings become older.. The graph for the last 24 hours is ap-
parently more pointed above than that for the v;hole period,
and this, in turn, is less flattened than that for the first
part of the period. For the very first stages of germination,
it appears that the organism is not so sentltive to temperature
differences as it is for later stages. This is in general
agreement with many physiological observations.

Another interesting point brought otit by these
graphs is that each curve is very nearly symmetrical about

the vertical A3tie/ that represents its maximujn (optimum

/ /
temperature), as far as these data show. This does not appear

to be generally true in growth and other biological processes;

in many cases reported in the literature (see Lebenbauer, cited

just below, for example) the upward slope of this sort of graph

is more gradual than the dov/nvmrd slope.

L.

-56-

Teinperature Coeff iolents for ghoot Elongation.
■fTobably the^most satisfactory method for
characterizing the temperature relations of anjr process is
that employing temperature coeff icients« f 10 } The temperature
coefficient for a given process and for a given temperature
interval is the quotient obtained by dividing the rate for the
higher temperature by that for the lower. The Interval is
conveniently taken as lO^c.and the symbol for the coefficient
is generally expressed as o7l(\. The values for Q/1'3\ were
obtained fo^ shoot elongation in these seedlings for the entire
period, for all the 10-degree intervals available. The upper
graph of figure 1 was used for determinng the approximate
hourly rate for each temperature from 13 pl'^o 35°C. The rate
for 13° is ,S9mm. and that for 2Z° is 1.30 mm., so that tfee-
c/lA (13°-23°) is, 1.30 divided .29, which is 4.5. The values
of ^/ld\ obtained for all the 10-degree ranges are presented
in table VIII which is self-explanatory.

(10) "cor roferenooo-to -%he- literattire on this
subject see the following, and the references there given:
Livingston, B.E. and Livingston, G.J, Temperature coefficients
in plant geography and climatology. Bot.daz. 56:349-375.1913.

Lehenbauer,P.A. Growth of maize seedlings in relation
to temperature, Physiol. 'Res. 1:347-286.1914.

Eanitz.Aristides, Temperatur und Lpbensvorgjlnge.
Heft 1:3-175. Berlin. 1915.

Fawcett,H,S. The temperattire relations of growth
in certain parasitic fungi. Univ. Calif .Piib.Agri. Sci.4 :183-232.

1921;.'

-57-

^yA( FOR

TABLP; VIII.
TEN-DEGREE TEV.PERATIJRE COEFFICIENTS (^

ELONGATION FOR THE ENTIRE CULTURE PERIOD

(ABOUT 110 HOURS.)

Hourly
rate for
lower
temper'ature

.Olrrj::.

29

40

54

67

79

90

99

107

115

123

130

137

143

SHOOT

^louxly

Temperature

rate for

interval

higher

Degrees G.

temperature

.Clmr. .

13-23

130

14-24

137

15-25

143

16-26

149

17-27

152

18-28

157

19-29

159

20-30

158

21-31

153

22-32

148

23-33

148

24-34

134

25-35

124

Q

a\

4.5
3.4
2.6
2.2
1.9
1.7
1.6
1.5
1.3
1.2
1.1
1.0
0.9

-58-

It has been custortiery to discuss tempera tixre
coefficients as though they v/ere constant for each process,
and "van't Hoff's*^ principle in this connection has been
stated to the effect that chemical processes have a value
of C/ao\ rb out 2.0 or 2.5. As Pavfcett has emphasized,
however, the value of O/ldyvaries in magnitude, for any-
process, from infinity to zero. and the process is best
characterized (as toti.ts teraperat^^re relations) by showing
just how this variation occurs. For the growth data here
considered this is readily shovin by. a graph such as that
presented in figure 2, in v;hich the several temperature
ranges are presented as abscissas and the coefficient values
are shown by ordinates. Inspection of this graph shows that the
temperature coefficients for the shoot growth of these seedlings
follows the general law for such coefficients. For lov/ temper-
ature intervals the coefficient value is of cotirse infinite,
and for high intervals it is zero. The invervening values
/factually shown by fig. 2 ^^ vary from 4.5 (13 - 23 Jto 0.9
(25 -35°). AS to the Vant Eoff principle, like all other

A

processes (whether physical or chemical), this one of shoot
growth shov;s one interval for which the value of ^Aoyis about

2.5; in this particular case this interval is about that from

o o
15 to 25 . If attention were confined to the temperattire

o o

range from about 15 to about 27.5 the conclusion might be

reached that the coefficient here considered has a value bf

about 2 to 2.5. But the important feature to be considered is

9 1

rr,.

LEGEI'ID FOR FIGURE 2.

Figure 2. Graphs of 10-degree tempera-
ture coefficients (_Q/iC^ for shoot elongation
far entire culture period. The different
temperattire intervals are indicated on the
axis of ; abscissas and"* the values of ^/^
are shown by the ordinates.

a

"rrr

TTTZ

r^

T-j-|T-|-i III I I I n I I rrry r-m-| i i i i | i rrv'[ -|-t

j rr| I I I I |4(J-L[_Llaj_|_LU-L|-

T

l#-23° ' IB^ES^iITQ^STO ! l^-i290 £ 1^ Z 1

2323^

25^35^

-59-

the fomi of the curve representing Q /io\, Fev/cett has published
a number of such ciirves end the one here set forth should be
compared with those. If certain magnitudes of the value of
Q/lo\are to be considered specially (as the range form 2.0

to 2.5, for example), it may be stated that this range rep-

0

resents 10 - degree temperature intervals betv/een about 15 and

o o

27.5 . For intervals including temperatures below abovit 15

the coefficient value is greater than 2.5 and for intervals
including temperatures abOT*t 27.5 the value is less than 2.0-..

A

It is interesting to note that the coefficient has a value

o 0
of unity for the 10 - degree range form 24 to 34 , end that

',, } '

the center of this range is 29 . This is additional

evidence that the optimum temperature for these tests is about

o
29 , the coefficients show that 10-degree ranges centering

below 29 give Q/io\as greater than unity, while those centering

o X

above 29 give ^yiOygs less than unity.

\

-60-

Conclus ions »

One of the aims of this study ¥/as to obtain

salt; and
evidence as to what set of /salt proportions and what

teraperatxc'e might give the most rapid germination of wheat/
■Hi early /

and^most favorable /growth of the seedlings, so that

definite recomjuendatlon might be niade for the preparation
of seedlings for solution cultures such as those outlined
in the "Plan for Gobperatlve Research." As far as the
results of these tests bear on the question, it msy be
said that of the 126 different solutions tested, no one
is clearly and definitely more promising than any other,
fctr the total concentration tere used (equivalent to
about 0.1 atm. /osmotic pressure) and for the first fo\xr
or five days after the dry --.r^.:^^ seed is placed in contact
with the medium. -Ithin the limits set by the Innate vari-
ability/ of the seed used, it r^iust be concluded that the
percentage' of germination and the rapidity of shoot
elongation v.-ere not measurably Influenced by the solution
tjTje or the salt proportions in these tests, ITils appears
to mean that.v/ith seed such as this and with the total solution
concentration here used, all of the 126 solutions tested
must be regarded as abor.t alike, within the ordinary
temperature range for wheat growth, in their suitability for
promoting the development of seedlings 4 — 5 cm. high.

-61-

although for later growth some of these sets of salt propor-
tions are undoubtedly very poor and others are much better.
It therefore seems safe to continue using Shive's
solution r5c2^ 0.1 atm.) in preparing seedlings for solution
cultiires, as recommended in the "Plan", or to use any set of
salt proportions lying in the middle portion of the triangular

diagram. shive's P5C8 is IR?),85l.l on the diagram used in the

"i
present studies; that is, 9.8 eighths of all the salt molecules

placed in the nutrient solution are VMn^OA 1,1 eighths a^e
Caflf03)o, and 3.1 eighths are r,!gS04. Such simple solutions as
IR3S2 or IR3S3 (both 0.1 atm. ) may therefore be expected to
give results about as good as any other. The salts used for
solution type I are relatively satisfactory from both the
physical and chemibal points of view, and it may be stated
that, so far as this study is concerned, they are just as
promising as any of the others.

It should be kept in mind also, that the solution
used for the preliminary preparation of wheat seedlings for
solution cultures ought to have a considerable total concen-
tration, Distilled water was markedly less efficient than
any of the solutions used in these tests, Ij seems safe to
recommend a total concentration at least as great as that
here used. Perhaps a still higher concentration might
give even better growth, but no evidence with regard to this
question is available.

ith. regard to temperature, the resiiLts reported
in this paper irtilcate that any inaintained temperature
between 28° and 31o C. may be expected to give about the
maximum rate of shoot elongation fbr such seeds as these.
For a very rapid rate of germination and subse-
quent growth of shoots until the latter, are 4-5 em. long a
teKperatvir e of 29° C. m.ay be selected v/ ith a solution. as
for example^ IR332 (0.1 atm. ) ^ Under these conditions, it
should require about 25 hours, to obtain (from seed lilce
that here used) seedlings having a shoot length of 4 cm.

after the shoot has broken through the seed-coat, and

^^laced
about 95 hours after the dry seed has beeii m contact v/ith

the solution.

These recommendations are based on the svipposition

that it is desirable to secure about the most rapid

development of shoots during their germination phase. If a

slower development is requisite, probably most physiologists

;"ould agree that it would be better to retard grov.th by using

a temperature somewhat belov; the optimum rather than above it.

maintained
Prom the graphs of figure 1, a/temperature may readily be

chosen, such Lhat any desired rate of shoot elongation may

be approximated, .hether it is desirable, in preparing

seedlings for solution cviltures,to allow gei^niination to

occur under nearly optimal ccnditions, cannot be stated.

-63-

Nevertheles s, fcr the sake of subsequent comparisons, it
is surely desirable that all the seedlings used in any
comparative study should have been subjected to the same
germination conditions, v/hether these be optimal or sub-
optimal. It may often be most satisfactory to employ for
germination the same temperature conditions as are to be
used for later phases of grov/th. It is not, however, the
purpose of the present paper to enter into any discussion
of this fundar.iental question; such a discussion would
require experimental evidence that iias not yet been
secured.

-64-

SUMMARY.

Before proceeding to summarize the results of
this study, it may not "be out of place to emphasize the
application, in this case, of certain fxindamentai principles
sometimes seemingly neglected. These points emphasized in
this paper are "based primarily on the results of the experi-
ments of this particular study. Up attempt is made to make
the statements of this summary applicable to all plants, nor
to all v;heat seed, nor even to all "Marnuis" wheat seed. They
refer simply to this lot of wheat seed in these tests and to
the first phase of development, ahout 110 hours from the
beginning of the soaking of the seed. Similarly, they
refer only to the maintained temperatures here employed,
to, the total concentration (equivalent to about 0,1 atm.
of osmotic pressure) of the feblutions used, to the 126
different salt compositions outlined in the "Plan for
Cooperative. Research, " to the absence of light from the
culture chambers, and to the various other details that
may have been effective in controlling the results of this
experimentation. The present paper is simply a report on
the results secured from these tests and on the relations
that obtain among them. "Aether other seed mifht exhibit dif-
ferent relations for this same physiological phase o:^ develop-
ment and for these treatments Is of course not predictable

-65-

from the present results. From the v;ork of many earlier
writers, and also from other results obtained b;- the
present writer in other connections, it is safe to say
that later growth phases of this seed or other salt
combinations or total concentrations, would give very
different indications from those here broxight forward.
The complexity of the internal and environmental control
of developmental and growth processes should be borne In
mind when reading the following statements, and it should
not be forgotten that the particular lot of seedused, in
spite of an effort to secure uniformity ( g, highly desirable
feature in a study of this kind ), nevertheless manifested
a low degree of uniformity, that is, the seedlings were "^
characterized by a marked degree of Internal variation.
The main points brought out in the preceding
sections of this paper are summarized below:

(1) 71 thin the limits set by the 126 different

solutions used, no significant relation between the compo-

of
sitlon of the medium and percentage/germination of the

seed was apparent.

(2) Similarly, no relation was apparent between
the percentage of germination and the temperature at which
germination occurred. The rapidity of germinatl on was.

-66-

of course , Influenced by temperature , and in a marked
way, though this relation was not quantitatively
studied.

(3) 50 significant relation between the salt
composition of the medium was clearly apparent. Tfhat ever
influence might have been exerted by these environmental
features was masked by the influence of the relatively
large internal variation ehorni by the several lots of 25
seeds. For later developmental phases, or perhaps for
these early stages of growth , with this same kind of seed
if its internal variability were much lower , relations
between growth rate and the composition of the medium
may be expected to become manifest.

(4) For all temperatures, excepting the lowest
here used (13 C.), distilled water as a medium appeared
to give rates of shoot elongation for the entire culture
period f about 110 hours) that were only about half as large
as those given by the nutrient solutions. Although the kind
of solution was apparently without significant inflxience on
the elongation rates of these shoots, and any solution

must therefore be regarded as just as promising as any
other in this respect, yet any one of these solutions was

-bV

appai'ently better as a germination medium than v^as distilled
water. For the lov.est tempei-atur e vised (13*^), how* ver,
distilled water is indicated as just as satisfactory as
the solutions.

(5) Despite the great degree of Internal
variation in the seed used, the usual tempe ratio's inflvience
was clearly brought out with regard to the rate of shoot
elongation. The influence of maintained temperature
was so great that it far surpassed the influence of
internal variation. All the solutions used with any
temperatijre v/ere treated as if they had been just alike,
and an average hourly rate of shoot elongation was obtained
for each of the seven temperatures used. These average
ho\irly rates are as follov^s in terms of hundredths of a
millimeter :

not Temperature, Centigrade.

130 170 210 250 28^ 31° 35°

For first part
of period,
(about 86
hours . )

For last 24 hours
of period.

29

For entire period

7

9.5 23 32 40 42 31

85 112 137 157 153 124
25 42 55 66 67 53

The optimum temperatiire , as shown by these averages, lies
between 28° and 31°, probably between 29° and 30°.

-68

(6) The growth -temperature graphs are uniformly
flat at the top, which indicates that there is e consider-
able range of temperaturey all of which are about alike
in their suitability for producing the highest elongation
rates. Any temperature betvjeen 28° and 31°, inclxisive,
may be regarded as practically optimum, as far as the
results show. 'ITie graph for the la£:t 24 hours is more
pointed at the top than that for the whole culture period,
and the one for the whole period (about 110 ho\irs) is more
pointed than that for the first part of the period (about
86 hours). ^^/t-^ ^^^^^J f^^,A^ ^ fiMd/pt-^ e>/h^£y'^^ftu^

'e graphs are ell very
^ the

f^'^ ^(7) Tlie gro vrt,h- temper 8 tm<e
^ the

nearly s^mmietrical about A vertical line, representing
approximately 29.5°. as far as -aie results show. According
to the smoothed graphs, a maintained temperature of 25°
roey be expected to give sensibly the same grovvth rates
(\inder the conditions of these tests) as does one of 35°.

(8) The ten-degree temperature coefficient
for the rate of shoot elongation for the entitle culture
period (about 110 hours from the beginning of the soaking
of the seedi) follows the general lew that has been worked
out by earlier studeatB in this field. Its value is 4.5
for the temperature interval fi?om 13° to 23°, about 2.5 for
the interval from 15° to 25° and 1.0 for the interval from
24° to 36°. The last point indicates that th'^ ojtiiniiia
teni)erature i's' to be considered as about ?.9'^Ci

-69-

Llteratiire Cited*

(1) 3aitlett, H.H. See True, R.H.^f'nd Bartlett, H.H.

(2) Fawcett, H.S. The temperature relations of growth in

certain parasitic fiingl. Univ. Calif. Pub. Agri.
Scl. 4:183-232. 1921.

Idem. See Livingston, B.E. andFawcett, H.S.

(3) Gerlcke, Y.'.P. Influences of temperatut^e on the relations

betv/een nutrient salt proportions and the early
growth of wheat. Arner. Jour. Bot . 8:59-62. 1921.

(4) Hlbbard, R.P. Physiological balsnce in the soil solution.

Mich. Agric . Exp. 3ta. Tech. Bui. 40. 1917.

(5) Kanitz, A. Temperatuj' und Lebensvorgftnge . Heft 1:9-175.

Berlin, 1915.

(6) Lehenbauer, P. A. Grovfth of maize seedlings in relation

to temperature. Physicl. Res. 1:247-286. 1914.

(7) Livingston, B.E. (Editor,). A plan for cooperative

research on the salt requirements of representative
agricultural pljaits, prepared for a special
committee of the Division of Biology and Agriculture
of the National He search Council. 2nd Ed. 54 pp.
Baltimore, 1919.

Idem. Further studies on properties of vinproductlve

soils. U.S. JJept. Agric. Bvir . Soils 3ul. 36. 1907.

(.8) Livingston, B.E»_,and Livingston, G.J. Temperature

coefficients in plant geography and climatology.
Bot. Gaz. 56:349-375. 1913.

(9) Livingston, 3.E.,and Fav/cett, U.S. A battery of chambers

with different automatically maintained temperatiires.
Phytopath. 10:356-340. 192. 1920.

(10) Livingston, B.E.^and Tottingham, V;.E. A new three-salt

solution for plant cultures. Amer. Jour. Bot.
5:337-346. 1918.

(11) Martins, Vj.H. See Shive, J.V/.^and Martin, V/.ll.

-YU-

(12) IlcCall, A.G. The physiological balance of nutrient

solutions for plants in sand cultures. Soil
Sci. 2:207-253. 1916.

Idem. The physiological requirements of wheat and soy
beans growing in sand media. Proc. Soc. Prom.
..^ric. Sci. 1916:46-59. 1916.

(13) McOall, A.G.,and Richard, P. 5. Mineral food requirements

of ?/heat plant at 'different stages of its
development. Jour. Amer. Sod . Agron. 10:127-134.

1918.

(14) Hichards, P.E. See HcGall, A.G. , and Richards, P.E.

(15) Schreiner, Q.^ana Skinner, J.J. Ratio of phosphate,

nitrate, and potassium on absorption and grov/ th .
Bot. Gaz. 50:1-50. 1910.

Idem. Some effects of harmful organic constitiients.
U.S. Jept. Agric. Bur. Soils Bui. 70. 1910.

Idem. The triangle system for fertilizer experiments.
Jour. Amer. Soc. Agron. 10:225-246. 1918.

(16) Skinner, J.J. See Schreiner, 0. and Skinner, j. J.

(17) Shive, J. ',7. A study of the physiological balance in

nutrient media. Physiol. Res. 1:327-397. 1915.

Ideuu A study of physiological balance for bvxclmheat
gro'7n in three-salt solutions. I'. J. Agric. lap.
Sta. Bui. 319. 1917.

(18) Shive, J.'..'.; and I.Iartin, V;.K. a comparison of salt

requirements for young and mature buckv;heat plants
in v;ater cultures and. sand cultures. Amer. Jour.
Bot. 5:186-191. 1918.

(19) Tottingham, "' .E. A quantitative chemical and physiological

study of nutrient solutions for plant culture.
Physiol. Res. 1:133-245. 1914.

Idem. See Livingston, B.E..and Tottingham, ''-.F..

(20) True, R.H. Ilari-iful action of distilled water, nnev. Jour.

Bot. 1:255-273. 1914.

(21) True, R.M. ,and Bartlett, H.H. Absorption ard excretion of

salts by roots, as influenced by concentrations and
composition°fculture solutions. U.S. Dept. iigric.
Bur. Plant Ind. Bui. 231. 1912.

VITA. ■

The writer was born on a farm near Fremont,
Nebraska, August 30, 1884, the son of Charles L. and
Fredericka Teiersausen Gericke. He attended the district
schools in his toyhood. In Novemher, 1909, he entered
Iowa State College by examinations, and was enrolled as a
regular student in January, 1910. During the sunma: of
1911 he attended the University'' of Chicago. He was
graduated, with the degree of Bachelor of Science in
Agronomy, from Iowa vState College in June, 1912. He
was then appointed instructor in Soil Chemistry and
Assistant Soil Chemist in the Experiment Station of the
University of Call fornia. In 1915 he received tl:B degree
of liaster of Science from the University of California,
and in 1916 he w^s appointed Assistant Professor In Soil
Chemistry in the same University. In 1918 he was granted
leave of absence to study at the Johns Hopkins Universily .
He was a Fellow by Courte sy in the Johns Hopki ns Uni-
versity for the academic j'^ear 1918-19. He devoted his
attention at the Johns Hopkins University to Plant Ihy-
slology, as major subject, and Physical Chemistry and
Physiological Chemistry as first and second subordinate
subjects, respectively. He remained at this Universily

and continued his experiments throughout the summer of
1919, returning to the University of California in
October of the same year.

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