PJB-2009-250
AN INVERSE RELATION BETWEEN Pb2+ AND Ca2+ IONS ACCUMULATION IN PHASEOLUS MUNGO AND LENS CULINARIS UNDER Pb STRESS
RAFIA AZMAT1*, SABA HAIDER2 AND MAREENA RIAZ1
Abstract
This study focuses attention on accumulation of Pb2+ in root and shoot of Phaseolus mungo and Lens culinaris in relation with Ca2+ from nutrient solution in which PbCl2 was added. The plants were cultivated in natural environment. It was observed that Pb2+ physically blocks water uptake which results in decline length of root and shoot with reduced leaf size of both species. This may be attributed with reduced fresh weight, and ratio of dry and fresh weight of two species. The accumulation trend of Pb2+ and Ca2+ showed a linear relation in between applied dose and accumulation of Pb2+ in Phaseolus mungo and Lens culinaris which inversely related with Ca2+ contents of both members of Fabaceae family. The reduced Ca2+ contents was due to chemical similarities in between the oxidation states of two ions but smaller ionic radius and high density of Pb2+ helps in accumulation of it in tissues of both species. These interactions may occur at the cellular and molecular level and are the abilities of Pb2+ to displace Ca2+ during specific physiological process. It is likely that Pb2+ blocks Ca2+ efflux from cells by substituting Ca in Ca2+ / Na during some enzymatic activity.
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