Exogenous proline application enhances the efficiency of nitrogen fixation and assimilation in chickpea plants exposed to cadmium

Abstract

Seeds of chickpea were sown in the pots supplemented with 0, 25, 50 or 100 mg of cadmium per kg of soil. At the stage of 30 days after sowing (DAS), the raised plants were sprayed with 20 mM proline except for the control plants which received double distilled water (DDW). The increasing degree of damage caused by the increasing concentration of Cd in soil was partially overcome by proline application. The treatment of 25 mg Cd fed plants with 20 mM proline increased significantly the nodulation parameters, leghemoglobin and carbohydrate content, leaf nitrogen and root nitrate content, activity of enzymes nitrogenase (E.C 1.18.6.1), nitrate reductase (E.C. 1.6.6.1), glutamine synthetase (GS) (E.C 6.3.1.2), glutamate synthase (GOGAT) (E.C 1.4.7.1) and glutamate dehydrogenase (GDH) (E.C 1.4.1.3) over that of the control. The value of these parameters was found to be at par with that of the control in the plants exposed to 50 mg Cd per kg of soil and also treated with 20 mM proline. However, the treatment was not found to be effective in alleviating the adverse effects of 100 mg Cd per kg of soil.