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AN INVERSE RELATION BETWEEN Pb²⁺ AND Ca²⁺ IONS ACCUMULATION IN PHASEOLUS MUNGO AND LENS CULINARIS UNDER Pb STRESS

RAFIA AZMAT^1*, 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.

¹Department of Chemistry and ²Department of Botany, Jinnah University for Women, 5C Nazimabad 74600, Karachi, Pakistan.

^*E-mail: rafiasaeed200@yahoo.com