简介：Basedonthestrongchelatingpropertyofbathophenanthrolinedisulfonicacid(BPDS)withFe(Ⅱ),rootFe(Ⅲ)chelatereductaseactivityisusuallymeasuredwithaspectrophotometerusingMES(2-morpholinoethanesulfonicacid)orHEPES(2-(4-(2-Hydroxyethyl)-1-piperazinyl)ethanesulfonicacid)bufferinthedarkbecauseofhighautoreductionrateofFe(Ⅲ)inthepresenceoflight.However,theexclusionoflightisinconvenient,especiallywhenanalyzingalargenumberofsamples.TheobjectiveofthisstudywastodevelopanewmethodfordeterminationofrootreductaseactivityundernormallaboratoryconditionsusingasuitablebuffercompositionandFe(Ⅲ)concentrationtoeliminatetheautoreductionofFe(Ⅲ).AmodifiedmethodusingaTris(2-amino-2-hydroxymethyl-1,3-propanediol)bufferatpH7.5insteadofMESorHEPESbufferandadecreasedFeEDTA(Feethylenediaminetetraaceticacid)concentrationof50μmolL-1wasdeveloped.TheautoreductionofFe(Ⅲ)usingtheTrisbufferwasundetectablefortemperaturesat4and28℃andwasalsomuchlowerthanthatusingtheotherbuffersevenwithsunlightduringmeasurementofFe(Ⅲ)reduction.Furthermore,thedifferencesinFe(Ⅲ)reductaseactivityamong5plantspeciesand14redclovercultivars(TrifoliumpratenseL.)couldbeeasilydetectedwiththemodifiedmethod.ThemethoddevelopedinthisstudytomeasurerootFechelatereductaseactivitywasnotonlyeffectiveandreliablebutalsoeasilymanagedundernormallaboratorylightconditions.

简介：Toshowthevegetationsuccessioninteractionwithsoilproperties,microbialbiomass,basalrespiration,andenzymeactivitiesindifferentsoillayers(0-60cm)weredeterminedinsixlands,i.e.,2-,7-,11-,20-,and43-year-oldabandonedlandsandonenativegrassland,inasemiaridhillyareaoftheLoessPlateau.Theresultsindicatedthatthesuccessionaltimeandsoildepthsaffectedsoilmicrobiologicalparameterssignificantly.In20-cmsoillayer,microbialbiomasscarbon(MBC),microbialbiomassnitrogen(MBN),MBC/MBN,MBCtosoilorganiccarbonratio(MBC/SOC),andsoilbasalrespirationtendedtoincreasewithsuccessionalstagesbutdecreasewithsoildepths.Incontrast,metabolicquotient(qCO2)tendedtodecreasewithsuccessionalstagesbutincreasewithsoildepths.Inaddition,theactivitiesofurease,catalase,neutralphosphatase,β-fructofuranosidase,andcarboxymethylcellulose(CMC)enzymeincreasedwithsuccessionalstagesandsoildepths.TheyweresignificantlypositivelycorrelatedwithmicrobialbiomassandSOC(P<0.5),whereasnoobvioustrendwasobservedforthepolyphenoloxidaseactivity.Theresultsindicatedthatnaturalvegetationsuccessioncouldimprovesoilqualityandpromoteecosystemrestoration,butitneededalongtimeunderlocalclimateconditions.