32生长素的生理作用（32thephysiologicalfunctionofauxin）

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1、3.2生长素的生理作用(3.2thephysiologicalfunctionofauxin)ThephysiologicalfunctionofsecondauxinContentteachingThephysiologicalfunctionandmechanismofauxinAuxincanpromoteplantgrowth,canalsoinhibitthegrowthofplants:canpromoteseedgermination,alsoinhibitedgermination;canpreventf

2、lowerabscissionisthinning・Thisphenomenonisrelatedtotheconcentrationofauxinandthetypesofplantorgans・Ingeneral,lowconcentrationsofauxincanpromoteplantgrowth,whi1ehighconcentrationsofauxininhibitplantgrowth,andevenkillplants・Payattentiontotheorganthatproducesauxin,i

3、ngeneral,theauxinproducedbyitselfdoesnotreachtheinhibitoryconcentration.Topromotegrowthistopromotethelongitudinalelongationofcellsandincreasethevolumeofcells,thatis,auxinpromotesplantgrowthbypromotingcellelongation.Theauxincanpromotecellelongation,partlybecauseof

4、auxininducedcellwallacidificationofthecellwallrelaxation,plasticityincreases;ontheotherhandbecauseauxincanpromotethesynthesisofRNAandproteininthecells,soastopromotetheincreaseofprotoplastandcellwa11materialtoformanew・Two.ThecharacteristicsofauxinactionAuxinhasdo

5、ublefunctionsandsensitivityinfunction,andauxinhasobviouspromotingeffectonthegrowthoforganinvitro,butitisnotgoodforthewholeplant・PhysiologicalfunctionofauxinWhentheseedlingsarelaiddown,thegrowthofthestemandthegrowthoftheroottotheground(asshow

6、ninFig・3-12)andtheapicaldominancecanbeexplainedbythedualityandsensitivityofauxin.PhysiologicalfunctionofauxinUndertheactionofgravity,theauxinismoredistributedonthefarsidethanonthelowerside・Becausetherootismostsensitivetoauxin,itgrowsintheaux

7、inconcentrationisverylow,alittlehigherbutinhibitedthegrowthofstem,theleastsensitivetoauxinandauxininhighconcentration,istopromotethegrowth,thistimeistoinhibitthegrowthoftheconcentrationoftheroot・Itshowsthegrowthofthestemandthegrowthoftheroot・Itisgenerallybelieved

8、thatthetopedgeisduetothedownwardtransportofauxinbud,abudbudthataccumulatedinthesite,inhibitedthegrowthofthereason・Three・Auxinanaloguesandtheirapplicationinagri