Historic. archived document Do not assume content reflects current scientific knowledge, policies, or practices. 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 irErOCH CHO nape eee eg ee ES oF lle xpenimentaliresmlts= saan eS 4 Miaterials;and|methodss- ===. = = QoS UTI AV ee etd oes cee ee 11 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). 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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