Cadmium uptake character and stress effect on the growth and antioxidant enzymes activities in Raphanus sativus

The effect of cadmium (Cd) on germination rate, accumulation, and antioxidative response was studied in radish seedlings. The seedlings were treated with different concentrations of Cd (0-500 mg(.)L(-1)) in a hydroponic system. The rate of germination and seedling growth were markedly inhibited with an increasing concentration of Cd2+. A concentration of 500 mg(.)L(-1) Cd2+ inhibited seedling emergence by 8%. Cd concentration in roots and shoots of plants increased with the increasing concentration of Cd in the nutrient solution. The content of Cd in shoots and roots was about 20 and 25 times higher, respectively, than that of the control from the treatment of 500 mg(.)L(-1) Cd. The Cd2+ stress could result in lipid peroxidation and induced an obvious increase in MDA content. The effect of Cd stress on the membrane protection enzyme system was evaluated and the activity of CAT increased with the treatment of 0 to 250 mg(.)L(-1) Cd and then decreased with the higher concentration of Cd; however, the activity of SOD and POD significantly decreased with increasing concentration of Cd in the nutrient solution.