Physiological Response of Imperata cylindrica var. major Seedlings on Growth and Antioxidant Enzyme System under Cd Stress

摘要

The effects of cadmium (Cd) progressive stress on the seedlings growth and antioxidant enzyme system of Imperata cylindrica var. major were studied by pot experiments. The results showed that with enhancing of Cd treatments concentrations, the length of root, fresh weight of above-ground, dry weight, and soluble protein content of the seedlings decreased constantly after increased slightly at first, reaching their peaks at Cd concentration of 10 mg/kg; the length of root, fresh weight of underground and the chlorophylls contents of seedlings decresed under Cd stress. It showed that growth of /. cylindrica var. major seedlings was inhibited under Cd stress. The level of peroxidation of cellular membrance lipids and MDA contents of seedlings increased continuously under Cd stress. Furthermore, with increasing of Cd concentration, the catalase (CAT) activity decreased constantly after increased slightly at first, reaching their peaks at Cd concentration of 10 mg/kg. Meanwhile, the superoxide dismutase (SOD) activity decreased continuously, and the peroxidase (POD) and polyphenol oxidase (PPO) activities increased continuously. All above indicated that the balance of protective enzyme system was broken under Cd stress, and radicals and peroxides could not be scrubbed effectively, which caused the hurt symptom in seedlings.