Cadmium induced changes on proline, antioxidant enzymes, nitrate and nitrite reductases in Arachis hypogaea L

The groundnut, Arachis hypogaea seedlings, when grown in pot cultures for 10-25 days at 25, 50, 100 microM CdCl2, showed a marked decline in growth compared to control. Similar trend was observed for nitrate reductase (NR) and nitrite reductase (NiR) activities whereas proline, peroxidase (POD) and catalase (CAT) showed increasing trend when observed on the 10th day of the experiment. Changes have occurred in the physiological and biochemical activities which are observed even at low Cd levels (25 microM). At 100 microM concentration, with increase in experimental days, Cd has imposed drastic decrease in leaf and stem respectively where nitrate reductase has varied from 20.87-79.41 and 29.11-72.91% and nitrite reductase 21.66-79.41 and 43.58-75.92% respectively. Contrastingly Cd treated plant tissues showed an increase in proline 111.2-159.87% (percentage changes) and 131.23-212.16% for leaves and stems respectively. In addition cadmium caused significant changes in the activity of antioxidative enzymes, peroxidase 48.12-72.19% in leaf and 37.71-75.25% in stem and catalase 64.86-143.92% in leaf and 129.13-214.74% in stem as compared to control. The study concludes that the activities of NR, NiR, proline, POD, CAT are inhibited suggesting that Arachis hypogaea seedlings are under Cd stress affecting their growth.