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いざっと しだはめど あり たひる IZAZTSIDAHMEDALITAfrIR博士(農学)
甲 第361 号
平成17年 3月15日
学位規則第4条第1項該当
Genotypic Responses ofGrowth,Yield and Quality ofBread Wheat to HighTbmperatures duringVarious Growth Stages(コムギにおける異なる生育ステージの高温に対する生長、収
量および品質の遺伝子型反応)
昇一肇
浮
田野橋
中中高
小葉田 亨 山口武視
学 位論文 の 内 容 の 要 旨
Wheat has the broadest adaptation ofallcereals and morelandis devoted toits PrOductionworldwide than to any other commercialcrbp.The continuouslyincreasing demandfor wheat resultedinits expansion to bnvironments that are regarded as marginalbecauseofheat,droughtandsoilproblems.Heatstressisaproblemin40%of the wheat areasinthe temperate environments,While over7millionhaofwheat are grown under continual heat-StreSSed environments of arid and semiarid areas.The CentralclayplainoftheSudanisatypicalexampleofthehot,irrigatedandlowhumidity environments ofwheat production.The development ofheat-tOlerant wheat cultivars CaPableofproducinggoodyieldandacceptablegrainqtialityiscrucialforthesuccessfu1 PrOductionofwheatintheseenvironments.Thisstudyinvestigates: 1-The e鮎cts of hightemperature on grain yield and quality and the difEbrential responsesofwheatgenotypesgrowninahotirrigatedenvironment. 2-Selectioncriteriaassociatedwithyieldunderahotirrigatedenvironmentthatcould acceleratethedevelopmentofheat-tOlerantwheatcultivars. 3-Thecapabilityofdi鮎rentbreadwheatgenotypestoremobilizenitrogen(N)andtotal non-StruCturalcarbohydrates(TNC)storedintheirstemsunderheatstressconditions and the association ofN and TNC remobilization e瓜ciency with grain yield anditsCOmPOnentS. 4-Thee鮎ctsofhighsoilandhighair/soiltemperaturesduringearlyandgrain且11ing stagesonwheatgrowth,grainyieldandrelatedtraitsandtheirdi鮎rentialresponsesto suchstress. SeveralexperimentswerecarriedouttofulAI1theabove-mentionedobjectives・ 1-GenotypICandtemperaturee鮎ctsongrainyieldandquality Fifteenwheatgenotypesin2000/01and18genotypesin2002/03weregrownunder optimum andlate sowing conditions ofthe hotirrigated environment ofthe Gezira Research Farm,ⅥねdMedani,Sudan.Hightemperature signi丘cantly decreased grain yieldbydecreasinggrainweight.Genotypesrespondedtolateheatstressbyincreasing proteincontents,SDSsedimentationvolume(SDSV),mixographpeakheight(PH)and thedescendingslopeat2minpastpeak(DS).Incontrast,mixographpeaktime(PT)and thecurvewidthat2minpastpeak(CW)weresigni丘cantlydecreased.Genotypesvaried inmagnitudeofresponseofmostqualityparameterstohightemperatureduringgrain 丘11ing.Grain yield and weight were negatively correlated with most of the quality parameters.FlourproteincorrelatedpositivelywithSDSVPHandDS andnegatively withCWPTcorrelatednegativelywithDSandpositivelywithCWResultsindicatethat hightemperatureincreased protein content,SDSV and PH and hencethe gluten strength,butdecreasedflourmixingtimeandtoleranceandhencethedoughelasticity・ Grain quality could beimproved under hightemperature conditions utilizing the available variability;however,it might require evaluations under various growing conditions. 2・Potentialselectioncriteriaunderearlyandlateheatstresses This study was conductedfor two seasons at the Gezira Research Farm,Ⅵねd Medani,Sudan,uSingtenwheatgenotypesandthreesowingdates(early,OPtimumand late).Grainyieldofthethreesowingdatessigni丘cantlycorrelatedwithbiomass,grains m’2,SPikesm’2,graingrowthrate,biomassgrowthrateandvegetativegrowthrate・In addition,theearlysowinggrainyieldsigni丘cantlycorrelatedwithgrainsspike-1while thatofthelatesowingcorrelatedwithharvestindex,thousandgrainweightandgrain 丘11ingduration.Similarcorrelationswerealsofoundbetweentheheatstressintensityof yield andmost ofthecounterparttraitsinthe earlyandlate sowings.These results suggestbiomass,grainsm’2,SPikesm.2andvegetativegrowthrateasselectioncriteria under earlyheat stress.Harvestindex,thousandgrainweight andgrain growthrate couldbeusedasselectioncriteriaunderlateheatstress. 3,Remobilizationofnitrogenandcarbohydrateinresponsetoheatstress EighteengenotypeswereusedforNremobilizationstudywhilenineofthemwere
usedforTNCremobilizationstudyl Fivedaysafteranthesis(5DAA),halfoftheplants Weretakentophytotronswheretemperaturewasgraduallyincreasedandthemaximum WaS Set at380C while the other halfwereleftin a vinylhouse kept below300C. Signi丘cantdi鮎renceswerefoundamonggenotypesinpercentreductioningrainyield (GY),grainweight(GW),grain丘11ingduration(GFD)andharvestindex(HI)duetoheat stress.Heatstresssigni丘cantlyreducedtheNremobilizatione凪ciency(NRE)ofmostof genotypes;whileithassigni丘cantlyincreasedTNCremobilizationefficiency(TNCRE) and signi丘cant variation were observed among genotypes・NRE acr?SS treatmentS Signi丘cantlycorrelatedwithGY GWHIandGFD.TNCat5DAAnegativelycorrelated WithNat5DAAandHI,butthe TNCRE underheatstresspositivelycorrelatedwith mainstem GY GW and HI.The rate of chlorophylllossfromflagleaf positively COrrelated with NRE and TNCRE under heat stress suggesting alink betweenleaf SeneSCenCe and remobilization efBciency.Resultsindicate that heat stress negatively affectedGYitscomponentsandNremobilizationwhileitincreasedTNCremobilization duetotheincreasingdemandforresources. 4-Responsesofwheatgenotypestohighairandsoiltemperatures Three genotypes,Imam,Fang and Siete Cerros were grown under three temperature treatments during early and grain 丘11ing stages.The temperature treatmentsduringearlystageswere:(i)normalair/normalsoiltemperature(22/220C), (ii)normalairnlighsoiltemperature(22/380C)and(iii)highairnlighsoiltemperature (38/380C)andduringgrain丘11ingwere:(i)26/260C,(ii)26/38OCand(iii)38/380C. Duringtheearlystages,highroot(22/38OC)andshoot/root(38/380C)temperatures signi丘cantlydecreasedPhotosystemIIquantumyield(◎psIi),Photosyntheticrate(An), SPeCi丘cleafarea and root growth ofthethree genotypes compared with the control (22/220C).Leafandshootdryweightandleafareaplant・1weresigni丘cantlydecreased by38/380Ctreatmentbutremainedunaf鮎ctedby22/380Ctreatment.Theheattolerant 封angalwayshadthehighestchlorophyllcontent(chl),◎psIIandAnunderalltreatments COnditions,WhiletheheatsensitiveSiete Cerrosalwayshadhighestreductioninthese traits especially towards the end of the experiment.Fang andImam responded to 38/380C treatmentbyimmediately andgreatlyreducing their shoot androot growth While Siete Cerroswas theleast afEbctedduringthe丘rstweek ofthe treatment.The SituationwasreversedwiththedurationofthetreatmentsuchthatSieteCerroswasthe mosta鮎ctedgenotypestowardstheendoftheexperiment.Itisconcludedthatwheat genotypesdi鮎rentiallyrespondedandadaptedto38/380Ctreatmentbyreducingleaf Weightandareaandhenceaccumulatingmorechlinthediminishedleaves.Thefailure toundergosuchchangesunder22/380Ctreatmentledtolowerchl,◎psIIandAn.
During the grain丘11ing stage,the26/38OC and38/380C treatments signi丘cantly decreasedchl,GFDandincreasedcarbohydrateremobilizationorlossfromthestemand theroot,butwithvaryingdegrees amonggenotypes.GY;biomass,GW;grainsspike-1 and HI under38/380C treatment were signi丘cantlylower than under the other twoJ treatments.Imam showedlower GY under26/380Cthan under26/260C,While Siete Cerros showedlower GY GW;grains spike’1and HI under38/38OC treatment.The resultsindicatedthathighsoiltemperaturealoneortogetherwithhighairtemperature decreased chl and GFD andincreased carbohydrate remobilization.Di鮎rential genotypic response to bothhightemperatures wasfound suggesting the existence of Variabilityamongwheatgenotypesinthisrespect. Itis concluded that hightemperatures at various growth stages studied here Signi丘cantly a鮎cted the growth,yield and quality of wheat.Immense genotypic Variations werefoundin their responses to high air and soil temperatures.Some Selection criteria wereidenti丘ed at various growth stages.The e鮎ctive use ofthese Selectioncriteriacouldgreatlyenhancethedevelopmentofheat-tOlerantgenotypeswith highyieldsandgoodgrainqualityundersimilarhightemperatureconditions.