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1、ThePlantCell,Vol.9,1055-1066,July1997O1997AmericanSocietyofPlantPhysiologistsSeedGerminationandDormancyJ.DerekBewleylDepartmentofBotany,UniversityofGuelph,Guelph,OntarioN1G2W1,CanadaINTRODUCTIONSeedsareavitalcomponentoftheworld’sdiet.Cerealagriculturalindustry.Extensi
2、vedomesticationandbreedinggrainsalone,whichcomprise-90%ofallcultivatedseeds,ofcropspecieshaveostensiblyremovedmostdormancycontributeuptohalfoftheglobalpercapitaenergyintake.mechanismspresentintheseedsoftheirwildancestors,al-Notsurprisinglythen,seedbiologyisoneofthemos
3、texten-thoughunderadverseenvironmentalconditions,dormancysivelyresearchedareasinplantphysiology.Eveninrelationmayreappear.Bycontrast,weedseedsfrequentlyma-tothetopicsreviewedhere,acasualperusaloftheAgricolaturewithinherentdormancymechanismsthatallowsomedatabasereveals
4、thatwellover5000publicationsonseedseedstopersistinthesoilformanyyearsbeforecompletinggerminationand700onseeddormancyhaveappearedingermination.thelastdecade.Yetwestillcannotanswertwofundamentalquestions:howdoestheembryoemergefromtheseedtocompletegermination,andhowisemb
5、ryoemergenceblockedsothatseedscanbemaintainedinthedormantstate?Obvi-What1sGermination?ously,withsuchalargeliteratureonthesubject,thisreviewisfarfromcomprehensive.Nevertheless,itprovidesbothanBydefinition,germinationincorporatesthoseeventsthatoverviewoftheessentialproc
6、essesthatareassociatedwithcommencewiththeuptakeofwaterbythequiescentdrygerminationandadescriptionofthepossibleimpedimentsseedandterminatewiththeelongationoftheembryonictheretothatmayresultindormancy.axis(BewleyandBlack,1994).Thevisiblesignthatgermina-Withtheseed,thein
7、dependenceofthenextgenerationoftioniscompleteisusuallythepenetrationofthestructuresplantsbegins.Theseed,containingtheembryoasthenewsurroundingtheembryobytheradicle;theresultisoftenplantinminiature,isstructurallyandphysiologicallyequippedcalledvisiblegermination.Subseq
8、uentevents,includingtheforitsroleasadispersa1unitandiswellprovidedwithfoodmobilizationofthemajorstoragereserves,areassociate