简介：AerobicricetechnologyisstillnewinMalaysia,andinformationregardingMARDIAerob1(MA1),thefirstlocalaerobicricevariety,isstilllacking.Therefore,comparativestudieswerecarriedouttodeterminethephysiologicalperformanceofaerobicricevarietyMA1andlowlandricevarietyMR253underwaterstressgivenatthepanicleinitiation,floweringandripeningstages.Thisexperimentwasarrangedinarandomizedcompleteblockdesign.Stomatalconductance(gs),chlorophyllafluorescence(Fv/Fm),leafrelativewatercontent(leafRWC),andsoilmoisturecontent(SMC)aswellasyieldcomponentparameterssuchaspaniclenumber,grainyieldand100-grainweightweremeasured.ResultsrevealedthatgsandleafRWCforbothvarietiesdecreasedwithdepletionofSMC.ThecorrelationstudybetweenthephysiologicalparametersandSMCindicatedthatFv/Fmwasnotaffectedbywaterstress,regardlessofvarieties.Theyieldcomponents(paniclenumber,grainyieldand100-grainweight)forbothvarietiesgreatlydecreasedwhenwaterstresswasimposedatthepanicleinitiationstage.Thisstudyshowedthatthepanicleinitiationperiodwasthemostsensitivestagetowaterstressthatcontributedtoasubstantialreductioninyieldforbothvarieties.Undertheaerobiccondition(control),MR253producedhigherpaniclenumber,100-grainweightandyieldthanMA1.AlthoughMR253isbredforlowland,itiswelladaptedtoaerobiccondition.