Sodium and Potassium Absorption and Distribution in Relation to Growth and Internal Potassium Use Efficiency of K—efficient and—inefficient rice genotypes

Apotexperimentwithtworice(OrizasativaL.)genotypesdifferingininternalpotassiumuseefficiency(IKUE)wasconductedunderdifferentsodium(Na)andpotassium(K)levels.AddingNaC1ataproperlevelenhancedricevegetativegrowthandincreasedgrainyieldandIKUEunderlowpotassium.AdditionofhigherrateofNaC1hadanegativeeffectonthegrowthoftheK-efficientricegenotype,butdidnotfortheK-inefficientgenotype.Underlow-Kstress,higherNaC1decreasedIKUEoftheK-efficientricegenotypebutincreasedIKUEfortheK-inefficientgenotype.Attilleringstageandunderlow-Kstress,addingNaClincreasedKandNacontentsanddecreasedtheratioofK/Naforbothgenotypes.Atharvestingstageunderlow-Kstress,addingNaG1increasedKandNacontentsandK/NaratiofortheK-efficientgenotypebutdecreasedtheK/NaratiofortheK-inefficientgenotype.TheaccumulatedNawasmostlydepositedintherootsandsheaths.Attilleringstage,theKandNacontentsandtheK/Naratiosindifferentpartsforbothgenotypesdecreasedinthefollowingsequence:K+insheaths＞K+inblades＞K+inroots;Na+inroots＞Na+insheaths＞Na+inblades;andK/Nainsheaths》K/Nainroots.TheK-efficientgenotypehadalowerK/NaratioinrootsandsheathsthantheK-inefficientgenotypeunderlow-Kstress.Atharvestingstage,KandNacontentsingrainswerenotaffected,whereasK/NaratiointhericestrawswasincreasedfortheK-efficientgenotypebutdecreasedfortheK-inefficientgenotypebyNaaddition.However,thiswasnotthecaseunderKsufficientcondition.