Alleviation of cadmium stress and improved growth performance of periwinkle (Catharanthus roseus L.) by foliar application of zinc oxide nanoparticles

Abstract

ABSTRACTCadmium(Cd)isanonessentialandverytoxicelementthatconfinesthegrowthofornamentalplantsworld-wide.Nanoparticles(NPs)havebeenusedasanovelapproachtoactasnano-fertilizersanddirectlyalleviatetheCdstress.However,itsdefensivemechanismsarenotwellunderstoodinornamental/medicinalplants,especiallyCatharanthusroseus(periwinkle).Theobjectivesofthecurrentexperimentareintendedtoexam-inetheimpactsofzincoxidenanoparticles(ZnO NPs;25mgl-1)onthereductionofoxidativestressbyenhancingantioxidantactivities,physiologicalimprovements,andelementalstatusinperiwinkleplantpartsunderCdstress(0.5mM).TheperiwinkleplantsweretransplantedandexposedtoCdstressoneweeklaterbysoildrenching,whereas,ZnO NPswereappliedafter14daysbyfoliarsupplementation.TheCdtoxicitysignificantlyreducedthemorphologicaltraits,negativelyaffectedthepigmentsandphotosyntheticappara-tus,abridgedantioxidantenzymeactivities,andCdaccrualinperiwinkleplants.However,exogenousZnO NPssupplementationproducedelevatedplantheight,flowernumbers,rootlength,plantfreshanddrybiomass,chlorophyll,andcarotenoidcontentsinCd-stressedplants.Likewise,theZnO NPshavealsoregulatedthegaseousexchangerates,antioxidantenzymes(SOD,CAT,APX),solubleprotein,andfreeprolinecontentsinCd-pollutedperiwinkles.TheapplicationofZnO NPsalsoconsiderablyreducedthehydrogenperoxide( 25%)andmalondialdehyde( 47%),activatedbyCdstress.Furthermore,theZnandCdcontentswerealsoelevatedandreduced,respectively,inZnO NPssuppliedCd-stressedplants.Thepresentexperi-mentrecommendsthattheexogenoussupplementationsofZnO NPsareafeasibleandsustainablestrategyforenhancingthegrowthattributesandreducingtheCdlevelsinperiwinkleplantsinmetal-hoardedsoilconditions.