Cadmium Accumulation and Antioxidant Enzyme Activity in Response to Cadmium Stress in Radish (Raphanus sativus L.)

The effects of cadmium (Cd) stress with different periods on Cd accumulation and antioxidant enzyme activities in radish plants were investigated with hydroponic culture. Radish seedlings were treated with 50 mg-L^-1 Cd²⁺ for periods of 0, 6, 12, 24, 48 and 96 h. The results showed that with the extension of Cd treatment, the Cd content in shoots and roots were increased, and most of the Cd accumulated in the roots, the ratio of Cd concentration in roots and in shoots ranged from 1.84 to 3.16. The activity of antioxidant enzymes including SOD, CAT and POD in shoots and roots increased initially and declined lately during the period of treatment. The activities of SOD and CAT in the shoots, and POD in the roots, increased significantly, whereas obvious declines in the activities of antioxidant enzymes were detected at later stage of exposure, and the activity of CAT in shoots and POD in roots was lower than that of the control.