Effect of arsenic on growth, lipid peroxidation and antioxidant defence system in cowpea

Arsenic (As) is a toxic ubiquitous metalloid. Exposure of plants to As can result in various morphological, physiological and biochemical variations. Hydroponic experiment was conducted to study the growth response, lipid peroxidation, proline and antioxidant defence system under arsenic (As) stress in the cowpea. Ten day old seedlings of cowpea grown hydroponically, were treated with 0, 25, 50, 75 and 100 μM (Na₂HAsO₄) sodium arsenate for 7 days and analysed for morphological and biochemical traits under As stress. Significant decline in plant root and shoot length along with biomass was recorded with increased arsenic doses, as compared to control. The As treatment resulted in increased proline and decrease in malondialdehyde (MDA) content in seedlings of cowpea with increased concentration. Enzymatic antioxidants like catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR) showed increased activity in dose dependant manner over control under As stress. Results indicated lower content of MDA and enhanced activities of the enzymatic antioxidant perform a significant role in As tolerance in cowpea.