NICKEL AND CADMIUM TOXICITY IN PLANTS

Abstract

Author(s): Asha Sharma, Anju Dhiman

Nickel (Ni) and Cadmium (Cd) considered as an essential nutrient where plants cannot complete their life cycle in its absence and cannot be substituted with any other element. Ni was first established as an essential nutrient for the completion of the life cycle and it was reported that Ni deficiency decreases the capacity of plants to develop viable seeds because of hindrance of embryo growth. The uptake of Ni in plants is mainly carried out through the root system via passive diffusion and active transport. The ratio of uptake between active and passive transport varies with the species. It has been reported that plant species and cultivars significantly differ in the uptake of Cd and its subsequent translocation from roots into shoots. Higher Cd accumulation in roots than leaves suggest that Cd transport to the xylem is restricted and Cd is not readily translocated in the phloem. Also, Cd accumulation in root and leaf also depends on binding to the extracellular matrix due to which a significant inhibition of root elongation may be observed. In a study, it was reported that Cd was translocated from lower leaves to upper leaves, and then from upper leaves to culms and ears. Lower leaves accumulated highest Cd content during the early growth stages. However, heavy metals accumulating in the food chain pose risk for health of living being as well as cytotoxicity in plants