Dormancy and the Effect of Storage on Oats, Barley, and Sorghum

Abstract

prev~nt "shock sprouting" during wet harvest seasons.Harlan 2 found that certain varieties of batley harvested in spring at Sacaton, .l'uiz"failed to germinate when seeded the same spring in the field at Aberdeen, Idaho, As a result of these general observations, the studies here reported were carded on with numerous varieties of oats, barley, and sorghum to test their dormancy reaction and to determine the effect of stomge conditions on afterripening, The work involved the makillg of some 40,000 tests of oats, barley, and sorghum; some studies were made with wheat and rice also, but the results wcre not sufficiently complete to justify reporting in detail.Incidental results of root hair develop ment and of the ~ffect of weather damage on the germination of sor ghum seeds also nre here reported. SUMMARYResults of studies of the effect in oats, barley, and sorghum of (1) storage conditions 011 aiterripening; (2) germination response to temperatures; and (a) varietal differences in~dormancy are presented.DOl'mancy in cereal~ IS expressed by failure of ~he seeds to germinate equnlly well over a range of temperatUl'es, l\[ost ('('l'eals completely afterripen when stored 1 to 6 months at 104 F, Freshlv harvested seed of dormant oats and badey kept at a low tempel'llture (36) in a relatively high humidity maintained dormancy fOl' It period of 3 years.In the case of oats, seeds stored at 36 F, came to equilibrium at 13 to 14 percent moisture, and those stored at 1.0-1, at (j percent or less.l\[ost freshly harvested dormant sC'('ds ~('rminated at a tem perature slightly above freezing (36) when conditions of moisture were favomble but failed to germinate at a rC'latively hi~h tem perature (86).Intact seeds that were dormant at a low tempera ture (36) germinated whell the coat was removed from over the embl'Yo, Storage at a relatively high tpmperatul'e Ci5<:l to 104) made germination possible at a relatively high telllp('!!'ature (8(;).As a:fterripening of dormant samp1efJ proce(d(c1, germination increased at the higher temperatures.As a mcaSUl'C of a:ftelTipening, rapidity of germination is more delicate than total germination, Drying oats at a low temperature (3(;0 F.) had little C'trectin over coming dormancy.Seeds stored in pm'tilll vacuum for 15 months at 36 were dried to below 6 percent moisture but failrcl to afterripen.Certain fungi, especially l1Zternai'ia sp" were mostly killed by storage at 1.0-1.Uf the oats studied.the mOht dormant was Yavilov.It small-seeded naked variety of the' spe('ies AL'('IW mulibt'('l'is Y:tV, In gelleml, the more clol'lnant varipties were .stl'ltins of the Red RlI!';tproof type followed by strain~ of Fulghum Ilnc1l!'nlgl'ain,As afterripenilig proceeds, germination of the seed increases at suc cessively higher temperatures.Varieties of badey show the same relative dormancy when grown under different climatic conditions and in eli n'el'cnt years; this confit'llls dormancy as a varietal chamcteristic.A total of 111 vltrieties of barley 'were seledell as being the most dOl'Ulant of the world collection.Dormant val'ieties t1re I'estricted in .reographicot'igin, coming from two somewhat adjacent areas, the Neftt' East and North Afl'iea.The first of these areas embraces the pt'e:::ent known rli!'b'ibution of H01'clC1.Hn sponta'lletl1n K, Koch.The world center for dormant bal' It,ys is therefore plae~d in between the two eentel'S of ol'igill (Abyssill itt and southeastern ASIa) as postulated by Vavilov.The least dormant 'Varieties come frvln Absssinia, There appears to, be all, association or llormancy and winter growth habit.'rests of 14'7 val'ieties of sorghum seed in 19{0 showed only 5 lots that could be considered partly dormant, 1 of w11 ich, the varipty Chicken Corn (So/'gltwn V'ulg(l1'(J dl'lbl1llllondii (Nees) Hack.), is lL sorghum that has escaped from cultivation and become n, weed P!-st.Dormancy is less com mOil in sorghum than in bade}' or oats and in these studies disappeared after:2 months' stol'age at 101 0 F, Kaolinng seedlings developNI 1110t'e abundant root hail'!'; than other val'ieties, Kafir se~c1 germinated more slowly than ot!\{'l' sorghums, Exposure to weathet' conditiol1s in the fiell!nHel' matllrity gl'(:!atly reduced ~enni nation, partiCUlarly in varieties having soft seeds, COlli pact heaus, and shOd glumes that leave the s('edexposed. REVIEW OF LITERATUREHarrington (11) 3 cites Duehnrtre (8) as on.;> of the first (18;;:2) to call attention to the effect 011 germinatioll of (h',Ying fl'(,..,hly harve:'tNl cereals,In Swe(len.a countl'y of short sea,iOIlS and moist climate.artifi('ial drying of grains to promote germination was long ago cOl1siclerrd prac,ticable.as r;ited by )1011er (it)), In fact.the Swedes wei'e amulg the first to recognize dOl'lllancy in cereals and its rrlation to stol'age lind germination..Attel:uet'g (.J), on the basis of studics of c('reals W:own in northel'l1 EUl'ope, defincs dormancy in cereals as resistance to germination at rclatively high tempel'tltures, and points out that o.fter ripening naturally takes place with !'ising spring tcmpe'l'tlt:ul'es.He found that ('ercal!' aften'ipen on ('xposUl'e to relativcly high te:1l1 peratures and may bp consirlpl,t'd fully uftpI'l'ipcned ",he'll they gel'mi nate readily at 30 C. (SO F".) and that unaftel'ripenecl cereals will !!l'J'lllinatl' at low tC'lllpCI'atlll'cS, He also states that IIHllly lots that do not germ inatc l'Pudily at :WO C, will gPl'lll inate at 1;')0.1:~ 0, or 10 0 , aml that ",11('11 til\' $('('11 wilInot gt'l'minatt' rpudily at 1:)', clryin!! al 40 0 fOl' a fpw <lays brings ahout: afte'l'l'ippning fllH1 ('onIJllpte gCI'rni nllt-ion at ~()?Hilt.nPl' (1:7) sc'pm!' to hayC' bC('n the fin:(' to (lplllolU;trnte tIlt' rpl:ltiol1 of til(' se('(1 ('oat: to dOl'lnHnc'v in el'l'pak Dr Ill'l'akinu til(' S('!'d {'oat, h(' ()bt:tin('(1 prompt gC'l'miliation of Illlai'tl'l'l'ipPIH'd' :;N'll.Hl' ap p:ll't'ntly waH not :Iwnr'!' of tilt' SPlIliPPI'lIlpahh' ('\1:11':1('(('1' of til(> {'out:, Jalt'l' lIpll1onstl'utp(l by BI'o\Yll (1).butnttl'ibutC'(] tlw rapid !!PI'minatiolf Italic IIUIlIIH'I'H ill ptll'l'lllh('Sl'S 1''f('[' to Litl'l'ntUl'p (,HPII, 11, :!O, 10 TECHNICAL BULLETIN-953, U. S. DEPT.OF AGRICULTURE AFTERRIPENING OF VARIETAL SAMPLES AIILINGTON, VA., 1\)30To determine the effect on afterripening of loss of moisture at low temperatures, samples of 11 of the most <lOl'/lUWt oat vHl'ietics fl'om the Arlington 1939 crop were stored at aGO F. fol' 3 months, both in the open und in it partial vacuum, and then tested for germination.The data nre shown in table 5.The moisture content given is that nt the end of the storage period.'l'AHLt] 5.-8tf(Jot of storage for 8 month8 at l16 F. in the open and in pw,tiaZ 't'a("UI(,'II~ on the average germinat'ion of 11 oat -va7'ietie.'l81w~v ing d01'17l(U/.('>Y