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CIRCULAR No. 377 NOVEMBER 1935
UNITED STATES DEPARTMENT OF AGRICULTURE
WASHINGTON, D. C.
VERNALIZATION EXPERIMENTS WITH FORAGE
CROPS
By Rotanp McKEs, senior agronomist, Division of Forage Crops and Diseases,
Bureau of Plant Industry
CONTENTS
Page . Ss Page
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INTRODUCTION
Studies reported by a number of investigators have called attention
to the influence of environmental factors during the germination
phase of growth on the later development and fruiting of the plant.
This general phenomena has been designated ‘ ‘vernalization.” It
also is referred to under the term ‘ ‘Jarovization” or “yarovization.”’
The economic objective of vernalization is the eHOntcrine of the
vegetative period and increasing yields of both seed and forage. The
hypothesis of Lysenko,' who has been the chief proponent of the
application of this principle, may be stated as follows: The con-
ditioning for sexual reproduction and vegetative growth in a plant may
occur in the seed when the embryo has started development but has
not yet, or scarcely has, broken the seed coat, if proper environmental
conditions are provided the seed at this time.
Thus vernalization is practically a seed treatment that influences
the plant in its later stages of development. The seed is started into
erowth by the application of a limited amount of moisture and then
subjected to other controlled factors: Temperature, light, darkness,
and time. The growth of the seed is arrested or controlled by lmit-
ing the amount of moisture, and in the case of seed treated at low
temperature the cold is a limiting growth factor.
In the case of winter wheat and other so-called ‘‘winter annuals’’,
the vernalization process consists of adding water to the seed in an
amount that will scarcely or just bring the seed into visible germina-
tion. This will require a 1- to 2-day period with the temperature of
the processing chamber kept at 10° to 12° C. The seed is then
transferred to a temperature of 3° to 5° and the moisture maintained
by addition of water when necessary, and the seed frequently stirred.
The time required in the cool room will vary, depending upon the
temperature and variety of seed, but from 35 to 45 days is average.
It has been pointed out by Lysenko that vernalization should be
1 LYSENKO, T. D., [[AROVIZATION IN AGRICULTURE.] Odessa Ukrainskii Inst. Selectii Biull. larovizatsii
nos. 1-3, illus. 1932. [In Russian.]
12604°—35—1
2 CIRCULAR 377, U. S. DEPARTMENT OF AGRICULTURE
completed in total darkness. Other investigators *, however, have
shown that this is not necessary or at least not for some seeds.
In the case of plants requiring high temperatures, such as corn,
foxtail millet, soybeans, Sudan grass, and sorghum, the vernalizing
process, according to Lysenko, is very much the same as with low-
temperature plants. In his experiments, where high temperatures
were used, sufficient moisture was added to the seed to induce swell-
ing or germination, and the swollen or germinated seed was then kept
for from 5 to 10 days at a temperature of from 20° to 30° C., depend-
ing upon variety.
The requirements for several different kinds of seed as given by
Lysenko are shown in table 1.
TABLE 1.—Requirements to induce vernalization for different kinds of seeds, accord-
ing to Lysenko }
Ratio of | Tempera- Ratio of | Tempera-
Crop water to | ture dur-| Time of Crop water to | ture dur- | Time of
weight of} ing ver- | exposure weight of | ing ver- | exposure
seed nalization seed nalization
Percent ce Days || Percent Ge: Days
Gorn! ee 30 20-30 10-15 |) Sorghum _---* = 26 25-30 8-10
Millet=22 se ee 26 25-30 5 Soybeans=s2=s- = 75 20-25 | . 10-15
Sudan grass_-_____- 26 25-30 8-10
1 See footnote 1.
Since the publication of Lysenko’s results, workers in the United
States have attempted to duplicate his experiments. Many data
have been published regarding the effect of low-temperature treat-
ments? but few regarding high-temperature treatments, and in the
latter case Lysenko’s findings have not been substantiated.‘
MATERIALS AND METHODS
The factors entering into the vernalization treatment were moisture,
temperature, light, and time. Ordinary commercial seed of the
various crops was used which in most cases had a high percentage of
germinable seed. In the case of crotalaria and hairy vetch, however,
hard seeds were present in varying amounts, which increased the
percentage of moisture absorbed, as the entire amount of moisture
applied was taken up by fewer seeds than would have been the case
had no hard seeds been present.
The amount of water added to the various lots and varieties varied.
with the amount necessary to induce germination and further in ac-
cordance with the object of the experiment. Stoppered bottles were
at first used to maintain the moisture content of the seed at a definite
percentage, but these later were replaced by Petri dishes. With the
lapse of time there usually was a gradual loss of moisture from the
2 SPRAGUE, F.S. EXPERIMENTS ON IAROVIZING CORN. Jour. Agr. Research 48: 1113-1120, illus. 1934.
3 MARTIN, J. H. IAROVIZATION IN FIELD PRACTICE. U.S. Dept. Agr., Bur. Plant Indus., 13 pp. 1934.
{Mimeographed.]
McKINNEY, H. H., and SANDO, W. J. EARLINESS AND SEASONAL GROWTH HABIT IN WHEAT. Jour.
Heredity 24: 169-179, illus. 1933.
SANDO, W. J., SWANSON, A. F., HUBBARD, V. C., SmitTH, G. S., SUNESON, C. A., and
SUTHERLAND, J.L. FIELD EXPERIMENTS WITH VERNALIZED WHEAT. U.S. Dept. Agr. Cire. 325, 8 pp. 1934.
4 SPRAGUE, F.S. See footnote 2.
Kirk, L. E. DIVISION OF FORAGE PLANTS, REPORT OF THE DOMINION AGROSTOLOGIST, Canada Expt,
Farms Rept. 1934,
VERNALIZATION EXPERIMENTS WITH FORAGE CROPS 3
seed and additional water was added to keep the percentage relatively
constant. The amount of moisture added to the seed in all cases was
determined by weight and expressed as a percentage of the air-dry
seed.
FIGURE 1.—White lupine. The vernalized plants (8) are in pod and well matured while the check plants
(A) show no sign of bloom,
For cold treatment of seed, an ordinary refrigeration room main-
tained at a constant low temperature (0° C.) was used. For high-
temperature treatment a small electric oven thermostatically con-
4 CIRCULAR 377, U.S. DEPARTMENT OF AGRICULTURE
trolled was used in some cases, while in others a steam-radiator
heated room served this purpose. In no case, however, did the tem-
perature vary much except when intentionally induced.
Seed treated at low temperature in the refrigeration room or at
high temperature in the electric oven were in constant darkness.
Seed treated at high temperature in the steam-radiator heated room
were subjected to a variation from total darkness to the intermittent
light of night and day. The duration of treatment with both high
and, low temperatures was more or less arbitrarily determined, but
consideration was given to experience of others doing similar work
so far as data were available, and an attempt made to use optimum
time rather than to use time as a variable in the experiment.
In the case of high-temperature treatments molds always gave
trouble and, while the use of disinfectants was attempted, no satis-
factory way was found for completely overcoming this difficulty.
Seedings in the greenhouse were made in large pots using an excess
of seed, and after the seedling plants were established the stands were
reduced to the same number of plants per pot for the different treat-
ments. Plantings in the open field_and coldframes were made in
rows with the stands approximate. Plantings in the open field were
made at the Arlington Experimental Farm, Rosslyn, Va., and the
coldframe and greenhouse plantings were made in Washington, D. C.
EXPERIMENTAL RESULTS
In table 2 is given the results from vernalized seed of white lupine
(Lupinus albus), crimson clover (Trifolium incarnatum), hairy vetch
(Vicia villosa), Austrian Winter field pea (Pisum arvense), double cut
red clover (7. pratense), and white sweetclover (Velilotus ‘alba). The |
vernalized seed was in the cold chamber for 40 days (Mar. 16 to Apr.
25). One check lot of seed was kept in ordinary storage and sown
dry at the time of seeding the vernalized seed, while a second check
lot was kept moistened for 6 days (Apr. 17 to Apr. 23) and then dried
for 2 days (Apr. 23 to Apr. 25) before sowing on April 25, 1934, at
which time the vernalized and dry check seed was sown.
In the case of the white lupine the check lots of seed, while making
as good growth as the vernalized seed, ‘excepting the one lot in the
ereenhouse, did not in any case come into bloom, while the vernalized
seed in all lots blossomed and developed seed pods (fig; 31):
Crimson clover check lots in all cases failed to blossom. This also
was the case with the vernalized lots planted in the open field and
coldframes, but the vernalized lot in the greenhouse bloomed and
made a larg er growth than the check plants (fig. 2).
The vernalized lots of hairy vetch seed bloomed earlier than the
dry seed check, while the swelled seed lot was in bloom at practically
the same time as the vernalized lot.
In the case of Austrian Winter field peas the vernalized lots blos-
somed decidedly earlier than the check lots.
The red clover lot of seed that was vernalized and grown in the
greenhouse blossomed earlier than the check lots; the lots in the cold-
frames all came into bloom on the same date, while all lots in the
open field failed to blossom.
None of the vernalized or check lots of white sweetclover bloktorhel.
and the vegetative growth was about the same for all treatments.
VERNALIZATION EXPERIMENTS WITH FORAGE CROPS OD
With reference to conditions for growth in the greenhouse, open
field, and coldframes, it should be recorded that in the open field
conditions were less favorable for growth than in the greenhouse and
in coldframes where artificial watering was practiced; and in the case
of the greenhouse plantings, temperature conditions were more
favorable for rapid growth during the early period of development.
The effect of the vernalization is most definitely shown in the green-
house plantings. Only in the case of hairy vetch is the development
of the preliminarily moistened and then dried seed advanced and this
only in the coldframe and field-planted lots.
It seems evident that lupines require a shorter period of cold to
induce normal development than some other winter annuals. The
FIGURE 2.—Crimson clover. The vernalized plants (2) are in bloom and later matured while the check
plants (A) never bloomed.
intensity of the cold and the time of exposure required probably are
contingent on other environmental factors. The white sweetclover
in this experiment showed no effect of the cold treatment and red
clover showed but little if any, while the hairy vetch and field pea
were only slightly influenced. This may have been due to insufficient
time or insufficient growth activity during the cold period. Johnson ®
reports that sweetclover seedlings 3 inches high gave greater response,
for the same period of cold treatment, than did three-leaf seedlings,
while swollen seed under the same conditions gave no response.
That all winter annuals may require some cold for their best develop-
ment and that all may differ somewhat in this requirement is at least
reasonably possible.
5 JOHNSON, I. J. THE PHYSIOLOGICAL EFFECT OF LOW TEMPERATURE ON THE BIENNIAL GROWTH OF SWEET:
CLOVER (MELILOTUS ALBA). Sci Agr. 12: 746-748, illus. 1933.
, U.S. DEPARTMENT OF AGRICULTURE
CIRCULAR 37
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VERNALIZATION EXPERIMENTS WITH FORAGE CROPS re
In tables 3 to 5 are given the results of tests with varieties of foxtail
millet grown in a greenhouse, and in table 6, tests with this crop
grown in the open.
As shown in table 3, the vernalized seed sown March 15 started
into growth ahead of the check, and the plants were slightly larger
throughout the period of development. The two lots, however,
headed at the same time. That sown April 5 was a little slower than
the check in starting and gave a very thinstand. At time of thinning,
when the plants were about 4 inches high, the vernalized plants were
stockier than in the check, owing to the thicker stand of the latter.
Later, the vernalized plants were larger than those of the check but
were delayed in coming into head. In the May 10 planting, the check
was as early as the vernalized lots, and the variation in total growth is
not significant.
TaBLE 3.—German foxtail millet sown in greenhouse
Culms headed on
Vernalization ~ date indicated
Length of culms!
|
} | |
| | na
Treatment PRATIO se | es ; ; : is | Remarks
| of wa- ay | May | May | June | Long-! Aver-
De emi |S | i artre |! is este] OPAL ee
seed |
nae: | eaeeti
| Num-| Per- | iu eee vum-| Num- |
ber \eccent- |" ©. bees | 6 a | ber | ber |Inches|Inches| Inches
CUNEO Fe as i a2 | Se es IS Sa aes ee at 5} 13) 34) 375 | 28.8 | Maturing June 13.
Vernalized ?___ 5 22 | 20-30 | 7 Ay Pale 38 | 419 |) 32.2 | Maturing June 13;
| = | | quickest in start-
ae ing.
| June 13 aie 23 | July 1
|
SINS ee ak ee eee 6 | 7 7| 39| 299 | 32.8
Vernalized 3___ 5 22 32 | 4 | 7 7 40 | 246 | 35.1
Wosess ese 5 22 32 | 0 | 5 7 Slee 295/242. 4
| | !
hie July | July | Aug. |
} | 15 17 | 20 | De’ |
| | |
| | | | | j
HOC Reece eee ces eg eee ee ef 2 ke iL) 1 3 58 | 60) 387 | 48.4 | Latest starting.
V seen len Biss. 5 22 | 20-23 i) 1 2 4\ 66 361 | 51.6
Dota 5 22 | 20-23 2 3 6 ite ~60 413 | 59.0 | Started first.
eens 7 26 | 20-23} 1 1} 2] 6] 534} 348 | 49.7 | Intermediate _ start-
ing.
| g
1 Ajl plants were mature when harvested.
= eee in alternating light and darkness and then dried 6 weeks and sown Mar. 15, 1933. Total=13
plan
3 Seed sterilized and vernalized in total darkness and then dried and sown Apr. 5, 1933.
4 Seed not sterilized but vernalized in total darkness and then dried; slowest starting; latest maturing,
sown Apr. 5, 1933. Total=7 plants.
5 The check by error had 8 instead of 7 ies
§ Vernalized in alternating light and darkness and then dried and sown May 10, 1933. Total=7 plants. -
8
CIRCULAR 377, U. S. DEPARTMENT OF AGRICULTURE
Taste 4.—Vernalized seed of foxtail millet varieties sown in greenhouse in mid-
Variety and
Vernalization
eae ae
|
|
— |
treatment 2S
SE
ee | a
== Te
S | 42)
Per- |
cent oe | ber
Common 2_____ SO 32h
Gheekee: = 2s. | Peale es ieee es
Common 2_____ 30 32 | 6
Checksse2 > 2 Ges 2 Phe es leeee e)
Hungarian ?___ 26 32 | 6
Check =. ee) eo
Hungarian ?___ 26} 32 | 6
Check 2242 [ees eee eee
Common 3_____ 30} 32 | 6
Gliecks eee | a Ree eaten
Hungarian 3__ 26} 32 6
Oulms
ber
fond fod
fed fed
NN OM O1rOrW I OW a1 1
Fae Num-
winter
i
Length of culms | | Heads on date indicated
; -
Date
| first
} S > S & = S ss
4 | Ee | < 2 Ne een. lee ee
| | | Num-| Num-| Num-| Num-| Num-
Inches| Inches Inches} | ber | ber | ber | ber | ber
10.0} 49 | 7.0| Mar. 9 | 3 7 7 rg ieee |
10g 50a 7.1) Mar. 17 0 1 5 7 rh
| 20.0] 133 | 16.6 | Mar. 15 0 6 8 8 | 8
20.0] 144| 18.0| Mar.17| 0 1 3 8 8
1150:| 97} 38:0.) Mars 29°]: ©)" 212 aa es
8.0} 7F| 5.5 | Mar. 15 0 4] 0 as 2 os
17.5} 69} 13.8 | Mar. 12 3 4 5 5 | 5
22700) 7h | tin? |oeedon 2 4) BO S| 5
LS Ost all Gu RAO Maroy est eee 0 4 §
23500 SUN etal Mie One es See 1 6] 8
18:0 {" 136) TSP Mar 26 |2.22-- | eee 0 cal 12
29.5 | S217 waAScOM Mar 19.) 5 es — [coe a Sart ares
1 Temperature at night was decreased to about 24° C.
2 Sown Jan. 11, 1934, the checks being planted on the same date.
3 Dried 8 days subsequent to treatment before seeding Jan. 19, 1934, the check being pianted on the same
date.
TABLE 5.—Vernalized seed of foxtail millet varieties sown in greenhouse in late
Vernalization i
|
|
| S > |
Variety and | ree pat
treatment | 73] = |
|e 2
S| ee |e ies
ay ae ~ i=
Pc. | °C. | No. | No
Sipenianaas= ss ayy |) 22 5
Ghecki22 9 — ee es Ere ee
Common ?__-_-_-_- 32 22 | ay |
Crecka === 5|===—— == ==
Hungarian 2____} 27) 22] ay |
@hGek:22 Fee tee vee ee ae aaa
'
I
|
|
ao
Siberian 3______- Sone on 5
Gheek:siiss SSA ee ene Neen me
Common 3______ SD alo 5
Check'3= 22 3v2 |e ieee eae
Hungarian 3____ DE |) Pe 5
CHECKS 2 Seas oe el | ee eee
i Seed dried subsequent to Mera a i eLOn:
2 Sown Aug. 24, 1933 and harvested Nov.
Sown Sept. 5, 1933 and harvested Nov. 7, 1933.
oo
STSUST ST ST ST!
O1rorld bo ww
SUMMET
Length of culms
Longest |
In. | In. | In. |
y-ts (2 a9
1G 8) 15
4 66 | «380
1 7 | 27
15 7 24
if eee
a|o | & |
41) 7 154)
114 Pio |
1S: 12 | 26)
1-2 8 25.)
1-2 . 10 iby
134; 10] 21
7, 1933.
Total
Date first head
Averare
Cm OOWw nT
Heads on date
indicated
eal
|
= *]
x =
S = © -
F ae 5
{
al No. fal No
5 6) 7|
i Nae A Poe
01 4] 6
On) ze ay,
G2 |. chal aba
4 oad
Pree
= S f? 4) oD =
=i = — N
ge [is me
SEO © Ss
o;O/90;0
paca Ss
On See 3
3} 3] 3 3
Lf ee 2
oO [ore 2
4) 45 4 5
il fan eS 5
j
VERNALIZATION EXPERIMENTS WITH FORAGE CROPS © 9
TABLE 6.—German foxtail millet vernalized and sown in the open in rows 20 inches
long and 6 inches apart, and harvested Aug. 18, 1933
[Maturity in checks and yvernalized seed in all cases was practically the same]
Vernalization | Height
|
: : Date
Treatment | ec Germi-| Culms | first
Ratio of, Tem- | nation | head
Days | water | pera- July 5} Final |
| toseed | ture
|
Number Percent| ° C. | Number) Inches | Inches |
(Check ee eo Oe se ae eo eae iene ee Bee Good - 54 26 oe | July 23
Rerializedees ss ays. Ee a See 5 22 22,| Bair-=- 30 30 72 | Do.
1D Yor Se Ses aimee heer eae Seas 5 22 22 | Poor_- 7} 30 68 Do.
TD Yor sR SEO I Ge ne eet Oe 7 26 PPA LW 29 30 68 | Later.
Wheckelees seme hed bas Sore Rue 8 [uh eee ere |S See eee Poor_- 16 19 64 | Aug. 1
Wernalizem:s erent 1 Oo 2. | 6 26 22 | Good - 49 21 64 | July 29
(TVG Kaas RRR Ee oe A epee ee Be pe ee Fair___ 33 20 64 | July 23
WS TLV Ae GG ee ra ee eee 6 | 26 22 | Good - 55 19 68 | July 29
Check 2s se ee ek ee |e es [ene dom 61 16 64 | Aug. 1
Wernalizedgome sat oats ee | 7 26 22) | =doles 69 16 64 Do.
QNGHE teheg LOSER a he ty see | 7 26 22a aoe 72 16 68 Do.
1D Yoyo: ee Ea ee ee 9 | 26 22a do= 32 16 68 | Do.
ID YO} GES =) OES Ne ees eee 9 26 22h ede 45 16 64 Do
1 Checks were seeded on the same date as the vernalized seed.
2 Vernalized in alternating light and darkness and then dried before seeding, May 22, 1933.
3 Vernalized in darkness and seeded without drying, May 29, 1933.
4 Vernalized in alternating light and darkness and seeded without drying, May 29, 1933.
5 Vernalized in darkness and seeded without drying, June 1, 1933.
6 Vernalized in alternating light and darkness and seeded without drying, June 1, 1933.
_ In table 4 the temperature was varied day and night with 32° C. for
the day and 24° for night. Theseed sown January 19 differed from
that sown January 11 in that it was dried subsequent to the vernaliz-
ing treatment. The results with the three varieties used in this
experiment show no injury from drying and no effect from the vernal-
ization.
The plantings of August 24 and September 5 (table 5) differ only
in treatment of the seed subsequent to vernalization. Seed of the
August 24 planting was dried slowly for 4 days, while in the Septem-
ber 5 planting the drying was continued for 15 days. The results of
the two plantings are similar and show no effect from vernalization.
The plantings made in the open (table 6) show some differences,
but these are not sufficiently consistent to be considered significant.
The tallest plants were from vernalized seed, but the time of maturing
was about the same in all lots. In the May 29 seeding, one lot of
vernalized seed was taller than the check while the other was equal.
In this planting, the date of appearance of the first heads showed a
week’s difference in the two check lots, but no difference could be
noted in the time of maturing of these and vernalized lots. The two
tallest lots in the June 1 seeding were from vernalized seed, but no
difference could be noted in time of maturing.
The results with Sudan grass given in table 7 are much the same as
with the foxtail millet and gave little or no indications of vernalizing
effects. While in the September 5 seeding one vernalized plant was
the earliest in bloom, the behavior of the other plants was such that
this is not significant.
10 CIRCULAR 377, U. S. DEPARTMENT OF AGRICULTURE
TABLE 7.—Vernalized seed of Sudan grass sown in greenhouse and harvested Jan. 31,
1934
aa = : _
= ae te Heads on date
| Vernalization Tadientod Length of culms
3 |
= o © S Longest
Name and treatment = = £ g
Fel 8 3
=o os gS (SA) fe)
Se ze n S = RN mi cD
n Le = = © ; : = : =| = =
esate = = = S) Ss) = a = = 3)
3 a D S 3 ® ® & a a iS >
A |e = a a al | (a) & D Ey eH | <
a | | | eee |
Num-| Per- Num- Num- Feral
ber | cent | °C. | ber ber ber ber tees Inches Inches Inches
Sudan grass_--_-_-__-- |) eile 45 22 5 | Nov. 20 fees: 6 57.50 | 293 | 48.83
Checkeet=-2 eae Beteoe Bee eee 5 | Nov. 27 2 5 a o 59.00 | 339 | 48.43
Sudanlerass==s eee | 2B ll mes 22 4! Dee. 4] i} 2] 4 | 2-3 |57. 50 196 | 49.00
Gheckse 2: 5.25 eee [ao eee ames ete igen Later | 0 2 | 6 Need 37. 66 | 226 | 37.66
|
1 Then dried slowly through 6 days and planted Aug. 24, 1933, the check being planted on the same date.
2 Then dried slowly through 6 days and kept dry 12 days before planting Sept. 5, 1933, the check being
planted on the same date.
It has been brought out in these trials, as in some earlier unpublished
work, that in the case of grasses and in certain legumes, seed that ,
have been slightly sprouted and again dried will start into growth
quicker than unsprouted seed. Legumes which have epigeous
cotyledons cannot be sprouted and dried without injury, but in the
writer’s experience legumes in which the cotyledons are hypogeous
can be sprouted and ‘dried several times without serious injury and
when sprouted, dried, and again moistened, start growth more
quickly than unsprouted seed.
It has also been shown that the capacity of seed to absorb moisture
varies greatly in different varieties as well as in different species, and
that the amount necessary to induce germination is about three-
fourths of the seeds’ total absorption capacity. The amount of
moisture necessary for germination, therefore, can be ascertained
approximately by determining the total absorption capacity. The
absorption capacity of seed of a number of plants as determined in the
course of these experiments, expressed in percentage of uae ordinary
air-dry weight of the seed, is given below:
Percent
Agrostis alba, (redtop) {2222 5 Ae Re ee ee ee 96
Cajanus indicus: (pigeonpea) 22 eee 129
Chaetochloa italica:
(Common -foxtail millet) ae Sacer es a a ee ee eee 32
(Hungarian:foxtathmillet) 2 29) Shed.) pet ee oe ee 28
(Siberian foxtatlmillet) > £2 27 eke ee ee a 39
Crotalaria:spectabults..5 =. Se ee oe 159
Crotalaria strigia® 202222. See Se ee ee eee eee 176
Dactylis glomerata (orchardtgrass) 26 22 ee ee ee ee eee Lis
Festuca -elatior (meadow fescue) Se ne eee eee 100
Hedysarum coronarizum, (Sulla) a2 2 2 ee ee eee 132
Lolium muticflorum, (italian, ty coats) ee eee 67
Lespedeza: sericéa.. =. = ee ree eee tees ne bee eng see See 125
Lumnus albus:(white lupine) =. 322-3 ee eee 152
Medicago sativa (common alfalia) 228 a ee ee ee 130
Melzlotus alba (white sweetclover)= = = ee ee eee 120
Pisum arvense (Austrian Winter fieldpea) S22 170
VERNALIZATION EXPERIMENTS WITH FORAGE CROPS lel:
Soja maz: Percent
GE Oxia SOs al) Rae see en ee ee sere Mg ed We ee So 136
(IA ING BUOY OVSEEN OL) ea eu Ee a) et ey Sg lee 130
(Beksmgasoyies im) amt t ie he ower oe en Sr Se Mo On ee 100
NORLUMEVULGALe, SUAGNENSE- (SUA OTASS)e = 2 45
ONG IMmUULGONCESACCLAGGALIEIIT: (SOLZO) ao aera ee ee 40
OM NCALNGLILNd> (ChIMNSONVCLONE! ian sean oe ee 130
LE ORUTD TCL OSE [CMA ONO) ee EE al eats ee ee ST ee ee 126
Vicriemonanihan Monat WagyeLe ln) pas se hee ee ee ee J 96
Vicor pono icon (bun CanlannVieLCh) = 26 oat ks See 101
Vicia saan Orevon, common veuch) =. 9-2 aes) eee PY pete iS 100
an easiest S(GLObunC OW, Cd) ra melee | oan See ree eee on ea 8 LBs
SUMMARY
Seed of white lupine, crimson clover, hairy vetch, and Austrian
Winter field pea vernalized or started into growth by the addition
of moisture and then kept for'a period of 40 days at 0° C., when
subsequently planted came into flower and fruit, while seed not so
treated remained in the vegetative stage or came into bloom at a
later date. Seed of white sweetclover and red clover showed no
response, but this may have been due to insufficient treatment.
Seed of foxtail millet, Sudan grass, soybean, and crotalaria mois-
tened and kept for a period of 5 to 9 days at high temperatures showed
in most cases decreased vigor and in no case did such treatment
advance the time of maturing.
Seed moistened and started into growth activity and subsequently
dried started into growth sooner than seed not so tr eated.
ORGANIZATION OF THE UNITED STATES DEPARTMENT OF AGRICULTURE
WHEN THIS PUBLICATION WAS LAST PRINTED
Secretary of Agriculture______- os A aa a ye Henry A. WALLACE.
Under Secretaria 2 =a gee ee Rex¥Forp G. TuGWELL.
ASSIStA NLS CORCLATY a= ae ee a M. L. Wiuson.
Directorsof Extensionaw onl <see aoee C. W. WARBURTON.
Dixector ofePersonn class = eee _... W. W. StocKBERGER.
Director ojelrfonmation saa] a eeeen es M.S. EIisENHOWER.
Director of Finance_____- a Maw 5 gh eek Tew ee W. A. Jump.
SOM CHO: ee enter yap ES Ag) abies mee Mastin G. WHITE.
Agricultural Adjustment Administration._._._ CHEsTER C. Davis, Administrator.
Bureau of Agricultural Economics______---. A. G. Buack, Chief.
Bureau of Agricultural Engineering____--_- S. H. McCrory, Chief.
Bureau: Of PATTON usiiy eee JoHN R. Mouusr, Chief.
Burpee ucojeStologicaliS (rue eee J. N. Daruine, Chief.
Bureau of Chemistry and Soils ____ meyeteg. Jyah H. G. Knieut, Chief.
Bureducoy Datruelndustj ae aes O. E. RexEp, Chief.
Bureau of Entomology and Plant Quarantine. Ler A. Strone, Chief.
Oficeiof_ Haperiment stations= a= JaMES T. JARDINE, Chief.
Food and Drug Administration__----_____- WatTER G. CAMPBELL, Chief.
Horest Serurces ca ee ee FERDINAND A. Siucox, Chief.
Grain Futures Administration_______-____- J. W. ff Duven, Chief-
Bureau.of Home Economics2= == = aaa Louise STANLEY, Chief.
EAU GLY. 8 oo es a ed i ae ee CLARIBEL R. Barnett, Librarian.
Bureau of Plant Industry_---------- _..-.-. FREprERIcK D. Ricuxy, Chief.
Burcat.of Pubiieaionds= == =e eee Tuomas H. MacDonatp, Chief.
Sol | Conservationgs crore = ae H. H. Bennett, Chief.
Weather Binet 332 So ee eee Wiis R. Greae, Chief.
This circular is a contribution from
JER Oy JEL nA IPG SIFO)] 2 = se FREDERICK D. Ricuey, Chief.
Division of Forage Crops and Diseases-- A. J. Pinrers, Principal Agrono-
mist, on Charge.
12
U.S. GOVERNMENT PRINTING OFFICE: 1935
Tor sale by the Superintendent of Documents, Washington, D. C. - - - - - - Price 5 cents