Aizo NoDA
Summary TheIe are皿any Studies on the embryo and seed germination of：cereals，but the
morphological，physiological，and ecologicalstudies of the coleorhiza aIe Very few and the natuIe Of the coleorhiza remains unexplained．
The preser）t author examined the seed geImination of ce工ealsin boiled water with diminished
OXygen SuPplyin1927−1928，found out that some cereals developed their coleorhizas exceedingly and others did not at al1after their kinds，and pDinteiout the necessity of the studies of the
COleoIhizain terns of seed germination．
Since then，the studies of the coleorhiza had sti11beeninactive and he reopened those st11diesin 1952．By the restllts of the studies on the coleorhizas of15crops，thei工Oute工andinner morphological nature was clearly reヤealed andalso their physiologicalfunction was made known
Then the ecologicalaspects of the coleorhizain cade of unfair conditions for seed germination Were Clearly found out，and the closeIelation between the drought resistance and salt resistance p工Ope工ties of the rice plant，and the high soilmoisture tolerance of wheat plant，Which an impo工tant prOperties of cer−eals varities，and the natu工e Of coleorhiza wasinvestigated
And theIelationship of ecolgicalstate of the coleorhiza to the geographic distribution of a variety OfIice plant was also examined，and thusit was broughtlight that the coleorhiza has animpoItant bearing on the ge工mination of seed and unknown prope工ties ofa variety of cereals．
Cllapterlい MorpI10log王ea18t11dies om仇e eoleorIliza．
rhe coleorhizais a sheath shaped organ that covers the seminalrootin eznbryo，and the
COleorhiza tissues consist of paIenChyma cells and contain no vascular bundle．When the seedsin dry are given a good condition to germination，the coleorhiza cells elongate and appear first out o董 the Seed coat．
Up to the present，it has been repor−ted that what appears first at the time of germinationis
COleoptile，Seminalroot，OICOleorhiza varying with the kind of crops．Butit has become evident that in husked gIain the coleorhiza first breaks the seed coatin allcases at ger皿ination；in unhusked
grain the coleorhiza can not be observed on account ofits husks，and when the huskis removed，the COleorhizais found to break the seed out fiISt aSin the case of the h11Sked grain．
1．The border tIetWeen the eoleol血iza amd tlle Other organs：・
（l）The boundary between the coleorhiza and sc11tellum‖Acco工dingtoREEDER（58），in the Festucoid type，the coleo工hiza agglutinateswith the scutellum andin the Panicoid typeit detachesitself from thelower paIt Of scutell11m，b11t the boundary between the coleorhiza and the scutellumis not observed
And SuETSUGU（66）（67）stated thatin the case of the wheat and the rye，the coleorhiza branches above thelower part of a scutellu皿butin the barley and the oat，it does not
ThIOugh the experinents onIice，Wheat，ba工1ey，Oatand．ryeit was ascertained that thecoleorhiza branched at about thelowest paIt Of the scutellumin allcases as faIaS the varieties of cereals the
present wrieer used were conceIned
The angles of the branches were small，the aIea Of boundary between the coleorhiza and scutellum
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being very wide．In the Panicoid type，COleorhiza braJIChed at theユowe工PaIt Oithe scutellu皿，
the coleorhiza diverged fIOm the scutelluminlarge area as both sides of tlle SCl】tellun overlapped and covered the coleoIhiza．
（2）The bo11ndaIy between the coleoIhizaand the epiblast：・
In the case of rice the工e WaS nO distinct border between the coleoIhiza and the epiblastin dry seed，b11tit became distinct at the geImination，because with the rate of the dilation of coleorhiza ce11s wa＄ greater・than that of the epiblast，and surface depression was observed between the coleorhiza and the epiblast．
In the case of wheat，Oat and finger mi11et，the bounda工y WaS disthlCtin dry seed beca11Se Of the difference of shapein the cells of both organs
（3）The boundaIy between the coleorhiza and the mesocotyl：−
In the case of barley，Zye and pearlmi1let，the boundary between the coIeoIhiza and the mesocotyl was easy to find becausein dry seed the cells of the董cImer WaS SmalleIandlcnger than those of tIlelatte工
In the case ofIndian corn andJob，s tears the distinct boIdeIbetⅥeen both organs was difficult to find at both the state of the dry and germination，for the coIticaltissue cells of the mesocotyl elongate at the sameIate aS the coleoIhiza ceils do at germination，aSit became distinct from the experiments on the crops mentioned above that the boundaIy between the mesocotyls and the semiI】al roots of these crops concuIS With that between the coleorhizas and the mesocotyls，that o壬Indian corn andJob，s tears should be the＿OutSide of the uppeIPart Of the seminalIOOt
2．The morphologIicalclassification of the coleorh重zas of cereals
F工Om the precedi王1g reS11王ts of studies，the bol】ndaries between the coleorhiza and the other
OrganS became distinct。．And the morphologicalclassification o董15cIOpS O董 ceIeals was made，the following points especially being main attention to：
The position of the coleorhiza separating from the scuteI王um and the expansion of both ends ofit COVe工ing the coleoIhiza，the epiblast present oIabsent，the cavity between the coleoIhiza and the Seminalroot，and branches of the coleorhiza tip oInOt
Chapt創r】Ⅰ．TheI】bysiolog王ぐalstl之dies on蝕e coleoIもiza．
The coleorhiza breaks the seed coat first and seems to be helpful to the progIess of seed geImination
As the main physiologlCalfunctions of the coleorhiza，SuCtion o董 water and absoIption ofmineIal substance we工e eXamined
1SⅦCtion of ⅥateT・○董 tlle eOleol血i2：a：−
When the coleorhiza of rice and wheat appea工S OutOf the seed coat and produces coleorhiza haiI，
if we soakitinち・畠oooo solution of neutralred at neut工alreaction，Ied co】or was suckedin coleo工hiza hair very soonAnd the degree of plasmoly苧1S Of the coleorhiza epideImis ofIndian corn was equivalent to that of O44moIsucrose solution，and the mean suction of water o董 coleorhiza tissue Of barnyard miiiet was tantamount to O．4moIsucrose solution
By：mean Of micropyrometer（needle method）the osmotic pressure o董 the rice coleorhiza tissue COuld not be dete工mined but the osmotic pressuIe Of the coleoIhiza tissue was similar to that of seminalroot
This p工OVed that the osmotic pressure of the coleorhiza waspretty bighin degree，Theincrease in the osmotic pIeSSure Of the coleorhiza tissue with that of the artificialcultl】re SOlution was
similar to the case of the seminalIOOt
These facts showed that the osmotic pressure of the coleorhiza was pretty highin degree
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The detection of components of sugarin coleorhiza at fullgrowth was held onIndian corn，by
paperchromatography，and sucrose was found to belargerin amount than glucose and fructose．One COleorhiza contains17γof totalsugar，From the above・mentioned experimentsit was made clear that the coleorhiza abso【bed water at germination
2．The fllmetion of at〉SOrbimg・minerals by仙e eoleorhiz孔：・
When geIminated rice g工ain p工Oduced the coleoIhiza hairin distilled water were placedin O．5％
NaCIsolution，Clenteredinto coleoIhiza hair onlyin aminute，and especially short hair was found to contain much Cl And Clmoved toward theinteIior of the coleorhiza an hourlater and about 5 hourslater，aCCumulation CIwas foundin the vascular bundles of scutellum，plimule and radicle．
After 6 hours，CIwas foundin the epitheriumlayer and endosperm too
When82p was painted on the surface of the wheat coleorhiza，11．5−15。5％ ofit was translocated into the plimule，andlO．5−24．5％into the radicle after 24hou工S
In the case of theIndian corn，the percentage of translocated82p wasless thanin the case of
Wheat，but82p was clearly tIanSlocated‖ Above expeIiments showed that the coleorhiza had the absorbing：mineralsubstance
5い TIlimfl11enee Of euttimg off the coleorIliza upom tIle grOWtllOf g・ermima．七重mg・org・anS：−
The experiments were done on later growth of the seedling when the coleorhiza had been cut off immediately after the appeaIanCe Ofits tip out of the seed coat ofIice and wheat，a harmfulef董ect WaS p工Oduced on the growth of seminalIOOtS，but none on that of the coleoptile
The coleorhiza seems to promote the growth of the工00t throughits physiologlCalfunctions Chapteヱ・Ⅱ．The e￠Olog・iealsttldies on tlle COleorhiza．
To clarify the ecologicalnatures of coleorhiza，abnormalbad conditions weze given And the followlng reSults were obtained．
1 Ecolog・icalnature of the coleorhiza under diminished water supply：・
Whenthe concent工ation of solutionis gradually raised，absorption of wateIinhibited，and thereis One phase between normalgermination and non germination that only the coleo工hiza breaks the seed
COat and does not promote growth．
The e MitteIe Saugkraft Maxima of h11SkedIice grain was equivalent to that of O小7，0り8 molof SuCrOSe SOlution and that of baInya工dmi11et Oh9〝1．O mol
The coleorhiza had the ecologlCalcharacter to continueits elongationin such a highconcentration of sucrose solution
2‖ The ecologicalnattlre Of the coleorhi2；a11nder diminished oxygen飢Ipply：−
In the case of ge工minationin boiled water with greatly diminished oxygen supply，both the COleorhiza and the coleoptile of rice and barnyaId whose orlgln SeemS tO bein a moorland，Showed abnor皿alelongation but the forageleaves and seminal root stopped their gIOWth．
In the other cIOpS the coleorhiza and coleoptile appeared fIOm the seed or only coleorhiza came out little．And there was a group whose seed germination was not seen atalL
As mentionedin the above results，the coleorhiza elongationis diffe工ent after the sort of cereals，
and crops were divided according to the nature of their coleorhizas．But when the restriction of the OXygen Supplyin the wate工 Seed germination was seenin the crops such as barley，Oat and rye，
though they djd not germinatein boiled water，and the coleorhiza appeared and showed abnorznal elongation一Such abnormalelongation was caused by the gIeat SWelling of the cells o董the coleorhiza
In the case of the rice，thelowestlimit of oxygen supply necessary for the develop皿ent Of the
Seminalroot seemed tolie near2．．5％aiIOf normalcondition，but the coleorhiza grew remarkably even undeIthe condition of O％air．
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Fron the results of experiments，it became evident that thelowestlimit of oxygen supply necessary for the coleorhiza breaking the seed coat varies with sort of crops，but evenin the diminished ofit that makesitimpossible foIthe seminalroot to develop，COleorhiza can growu
る。The ecolog・icalnature of the coleorhiza at the maximtlm and mhtimum temperat，11reS：−
When the rice varieties（Honshd，Japan）were beded at42OC，a gOOd dealof the coleor hiza appears from the seeds but the coleoptile showslittle elongation aftefWards and the seminalroot does not
appear at all，And alsolOOC，the type of germination was the same with the germination at the
maximum temperatuIe，and even after 5 weeks the seminalro〇t WaS nOt Seen atal1，thoughthe coleorhiza appears from the seed pretty much
When barley and wheat were bedded at theminimum temperature OOC，the coleorhiza breaks seed COat，but even afte工 2 weeks the seminalroots were not seen at all．The coleorhiza has the ecological nat11re Of capacity of emeIgenCe both at the maximum and minimum temperatures董or germinationl
4… The eeologiealnatllre Of the eoleor‡lizain thiek NaCIsollltiom
In the case ofunhusked grain，the emergence of the coleorhiza was not perceived fIOm the outside
Of the seed when salinity exceds2．0％，butin the case of husked riceit was visiblein such a high Salinity as5．0％or4．0％，andin some grains the coleoptile showed alittle growth afterwaIds，but the seminalroot was not pe工Ceived atall
Thus the process′Of germination was hindered when the outward condition of ger皿inationis abnormal，and someindividuals could develop their・COleoptiles only alittle but neither forageleaves nor seminal roots
It was moreover newly perceived from the point o王the organ of the embIyO，the coleo工hiza has an ecologicalnature of breaking the seed under such an abnormalcondition that neither the forageleaf nor the seminalroot does not grow
CIlapterⅣ．The relation betweerL the nature of the coleorhiza and varietal characteristics of
eX■OpS
From theinvestigationinto the relation between the nature of the coleorhiza and drought resistance and salt resistance of rice and next that betweenit and the degree of soilmoisture tolerance of Wlleat Va工ieties andlast the relationit and the geogr aphic distribution of rice，the fo1lowlng COnClusions weIe Obtained小
1．The relation betweem the nat11re Of the eoleorhi2：a and drought resistance of rice varieties：
As for a germination rate，On the dry soil（50％ wateICaPaCity）amoreIeSistant va工iety Sensh6
SprOutS faster thanin the case of aless resistant N6rin No．10。The embryo of SeTISh6，after having been removed from the seed bededin the dry soilfor12 hours，prOVed strongerinits absorption
O董 0Ⅹygen than that of N6工in No 10
StaICh was translocated to the coleorhiza and tip of the seminalroot appeared faster and morein quantity thanin N6rin No…10．1t was ascertained therefore that such a stIOnge工absorption of oxygen O董the embryo and such a faster staICh translocation on the dr・y SOilquicken geImination
2 The relation between the nature of the cole・Orhiza and salt resistamce of rice varieties A more salt resistant vaIiety of rice ge工minated faster than aless resistant one when they were keptin 5％−4％NaCIsolution of highconcentration，but at such a highconcentr ation of NaClthe forageleaf and the seminalroot did not gIOWin allvarieties
5．TIle relatiom between the nature of the coleorhiza and high soilmoisture toleramce of wheat
Varieti（！S．
Under the diminished oxygen supply that only permited the e皿ergenCe Of the coleorhiza a more highresistant vaIiety proved to appear and belargeIin quantity than aless moisture resistant one
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Itis wellknown a vaIiety of wheat high moisture toleIanCe One neededless cons−1mption of
oxygenat no工malseed germinationthanthatof a variety withalow one・From the experiment，in the diminished oxygen s11pplyunderwaterthat only permited thecoleorhizato eme工ge・−abnormalseedger皿inationNit was found the consumptionof oxygenofavariety ofwheatwi払hightoleranceof
moistureless than that of a variety with alow one
4い The relation between 蝕e nature of the coleorhiza and the geograpllic distribution of rice
Variet重es．
When the unhulled grains were germinated at the maximum tempe王atuIe42OC・Varieties of cool
regions wasinhibitedin the emergence of the coleorhiza，While varieties of thetIOPicalones showed good geImination rate as with the case of500C
The respiration rate of the embryo of N6Iin No．10（Honsh頁）proved higher than that of Eiko
（Hokkaido），eaCh being removedfromthe dry seed and where taken12hoursafter seeding at420C respectively．
Thus the fact that the respiration rate of the embryo of the vaIiety of cool工eglOnSislower than that of HonsI沌 Variety may willbe considered as a facto工 Of retarding the emergence of the coleoIhiza at a hightemperature．By the above experiments，a Close relation was fo11nd to exist
between the coleorhiza and vaI・ietalcharacteristics of crops
And so，the studies of the ecologicalnatuIe Of the coleorhiza have animportanceon the study of
crops，and afteIfurtheIeXPeri皿entS bea工ing many varieties the studies of the coleorhiza underabnormal condition willserve as a method whereby to examine varietalcharacteristicsin plant breeding
Cllapter V．でbeinvestigationimto tIle VaI王ol丑S如昭eS Ofseed germina七iom
The definition of seed geImination has been different with eachinvestigator，and an abnormal
geImination that only the coleorhiza emerges and does not grow seminalIOOt has beenassorted小 Therefo工e the pIeSent authoIis golng tO divide the seed germination processinto four stages・1．．The prevjoⅦS Stag・e O董seed g・erm玉na七重on：・
At the first stage of seed germination，the seed swells by water by physicalsuction and then
beginsits active suction of water
Large enlargement of the seedis considered as the first step of germination
The previous stage of germination is the period from the marked swelling of the seed until appeaIance of the coleorhiza out of the seed coat
2小 甘he early stage of seed g■erminatiom：−
The coleorhiza breaks the seed coat and continuesits gIOWth，While the other ozgans can not be seen．This stagelS Ca11ed the early stage of seed germination
5．The middle stage of seed酢rmimatiom：−
After the early stage of seed germination，the coleoptile or the seminalroot appears out of the
seed coat，but allthe elnbryonic organs aIe nOt COmPleted・This stageis called the middle stage o董seed germination
4．The finalstage Of seed germimation：−
Allthe oIganS Of the seedling such as coleorhiza，COleoptile，meSOCOtyland seminalroot appear out Of the seed，Seed germinationis now completed，and thisis the finalstage of seed germination・・
In accordance with the various stagles of seed germination the changes of activities of amylases during seed germination was examined and following results were obtained．In the early stage of germination the activitiesof amylasesinIice and wheatgrains werealmost simi1ar to thosein the
dry seeds
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Butin the final stage of seed germination，the activity ofα一amylasein rice andα・amylase and β−amylasein wheat grains became moIeintense than thatin dry seed．The activity ofβ・amylasein rice grain，however，became powerfulin24ho11IS after the finalstage of seed geImination
The conclusion o董this study of the coleorhi2；a Of ceralsis summarized as follows：一
By the morphologicalstudies，indistinct boundaries between the coleorhiza and the other organs of Seedling was made clear，and the morphologicalclassification of coleorhiza of crops was done
Andit was also brought tolight that the coleorhiza had the function of suction of water and absorption，and had a capacity of a geIminating organ
It was proved even under the unfavourable conditions of seed germination，Only the coleorhiza COntinuedits growth，and theIe WaS a Close relation between the diffe工enCe O董natu工e Of coleorhiza among crops and the characteristics of crop varieties
Lastly，by the studies of the coleorhiza，author suggested the advisibility o董 dividing seed geIminationinto 董our stages
Further studies on the coleorhiza are earnestly hoped for to be promoted hereafter．