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简介：Theeffectofbicarbonate(HCO3-)onthegrowthanddevelopmentofplantsvariesbyspecies.Tobetterunderstandinorganiccarbonandnitrogenassimilationchangesofkarst-adaptableplantsunderdifferentHCO3-treatments,weconductedexperimentsonseedlingsandinvitroplantletsofOrychophragmusviolaceus(Ov).Wefoundthatthevitalphotosynthesispotential(asmeasuredbynetphotosyntheticrate,actualphotochemicalefficiencyofphotosystem-Ⅱ,photochemicalquenchingcoefficient,andtheinstantaneouscarbonisotoperatioof3-phosphoglycerate)wasconsistentunderdifferentHCO3-treatmentsofOv.Bicarbonate’slackofeffectoncarbonassimilationofOvmayberelatedtocarbonicanhydraseinOvconvertingHCO3-toH2OandCO2.Inthisway,OvcouldpreventHCO3-iontoxicityandhighpHfromharmingitsgrowthanddevelopmentunderHCO3-stress.ThisstudyalsofoundthathighHCO3-concentrationscouldpromotenitrogenassimilationandutilizationofOvthroughchangesinrelatedindexes(foliarnitrogenisotopefractionationratio,stablenitrogenisotopeassimilationratio,foliarstablenitrogenisotopefractionation,nitratenitrogenutilizationefficiency,andnitrateutilizationshare)underdifferentHCO3-treatments.BicarbonatehasdifferenteffectsonphotosynthesisandoninorganicnitrogenassimilationofOv,whichmaybeconnectedtophotosynthesisprovidingelectronsfornitrate/nitritereductionthroughthephotosyntheticchain.

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