Investigation of cadmium and lead induced phytotoxicity on seed germination, seedling growth and antioxidant metabolism of chick pea (cicer arietinum l.)

Heavy metals accumulation in soil has become a worldwide problem, leading to loss of agricultural productivity. Lead and cadmium are the toxic elements of primary importance. A study was conducted to determine the effect of different concentrations of cadmium and lead on seed germination, seedling growth, oxidative stress and antioxidant response of Chick pea (Cicer arietinum L.). Seeds were grown under laboratory conditions at 0.25, 0.5, 1, 2 and 4 mM l-1of metal ions. All of these metals were added as single metal solution, i.e. one experimental set contained a single metal in particular concentration. A slight stimulatory effect on seedling growth was observed, especially at low metal concentrations (0.25-0.5 mM l-1). Both lead and cadmium treatments showed toxic effects on various growth indices of chick pea at high metal concentrations (1-4 mM l-1). The level of lipid peroxidation of germinated seeds was measured as Malondialdehyde (MDA) contents and were significantly enhanced by a high Cd and Pb concentration. The activity levels of some antioxidant enzymes such as superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6) and glutathione peroxidase (GPx, EC 1.11.1.9), did not change much at low metal concentrations, but fluctuated drastically at high Cd and Pb concentrations. These results suggest that Cd and Pb toxicity causes oxidative stress in plants and the antioxidative enzymes SOD, CAT and GPx could play a crucial role against oxidative injury.