Effect of Cadmium and Lead Stress on Seed Germination and Seedling Growth of Jatropha curcas L.

Abstract

Heavy metal pollution in the biosphere has become a worldwide problem. Metal industry effluents, mining sites, municipal and agricultural waste are important sources of metal dispersion in environment. Heavy metal imposed phytotoxicity affects seed germination, seedling growth, photosynthesis and other physiological processes. Exposure of seeds to cadmium (Cd) and lead (Pb) has deleterious effects resulting into inhibition of germination, delayed germination time and retardation of seedling growth due to toxicity. The aim of this research is to investigate the toxic effects of Cd and Pb on seed germination and seedling growth of Jatropha curcas L. and evaluate its tolerance for heavy metal stress. The experimental treatments included exposure to five concentrations of cadmium nitrate and lead acetate (ranging from 25 to 125 µM/L), under which the germination and seedling growth parameters were determined periodically. The germination and growth of J. curcas L. was affected by cadmium and lead supplemented at different concentrations and the toxicity effects were found to be concentration dependent. Tolerance indices declined sharply with increasing concentrations of lead and cadmium treatments. Germination was inhibited upto 50% by 100 μmol/L of Cd, 125 μmol/L of Pb. Mean germination time and seedling vigour index also gradually decreased with increase in Cd and Pb concentration. Cadmium proved to be more toxic than lead in all considerations.