Effect of lead and cadmium on aquatic plant Hydrilla verticillata

Absorption of different concentrations of Lead (Pb) and Cadmium (Cd) by aquatic plant Hydrilla vertcillato was measured during winter season for two different durations i.e. 3 days and 7 days. Effect of Pb and Cd was evaluated by analyzing various parameters such as biomass, total chlorophyll, carotenoid, protein, nitrate reductase activity, SOD (super oxide dismutase) and heavy metal uptake. Increase in biomass, total chlorophyll, protein and nitrate reductase activity was noticed at lower concentration of both metals whereas at higher metal concentrations of Pb and Cd, decrease in these parameters was observed i.e. it was concentration and duration dependent. Increase in carotenoid and SOD levels at high concentration of Pb and Cd indicated its ability of stress tolerance. Accumulation of Pb by test plant was found to be more than Cd at low concentration. Higher concentration of Cd and Pb caused toxicity which resulted in reduced plant growth and physiological activities.