NITROGEN METABOLISM AND ACTIVITY OF ANTIOXIDATIVE ENZYMES IN CHICKPEA PLANTS GROWN IN CADMIUM AMENDED SOILS

Abstract

The present experiment was conducted to elucidate the physio-morphological and biochemical responses of chickpea plants exposed to 0, 25, 50 or 100 mg cadmium (Cd) per kg of soil. Cd was given in the form of CdCl2. It was observed that all the growth parameters (length, fresh and dry mass), number of nodules, their fresh and dry mass were decreased with the increasing concentration of Cd in soil at both the sampling stage i.e. 60 and 90 days after sowing (DAS). The value of leghemoglobin and carbohydrate contents of nodules was also decreased in a concentration dependent manner at 60 and 90 DAS. However, the nitrogen content of the leaf of the plants fed with lowest concentration of cadmium (25 mg/kg of soil) showed a value which is comparable to control. As the level of cadmium increased in the soil, a concomitant reduction in the photosynthetic attributes as well as of leaf nitrogen and root nitrate content was noted. A significant reduction in the activities of nitrate reductase and carbonic anhydrase was also noted and the reduction was more significant in 100 mg Cd fed plants. The enzyme activities in 100 mg Cd fed plants decreased significantly by 37.9%, 38.0% (glutamine synthetase), 28.0%, 29.0% (glutamate synthase) and 46.0%, 44.0% (glutamate dehydrogenase) at two sampling stage (60 and 90 DAS), respectively as compared to control. However, unlike other parameters, the endogenous proline level and the activities of catalase, peroxidase and superoxide dismutase showed an increase with the increasing level of cadmium.