Antioxidant Defense System and Cadmium Uptake in Chinese Cabbage Cultivars under Cadmium Stress

This work was carried out in the sand-culture experiment, which aimed to analyze the cultivar differences in dry matter production, Cd concentration and levels of antioxidative defense systems. The results showed that the shoot biomass of New Bejing 3 and Suancaiwang increased in low-Cd supply (< 2.5 mg L-1) and then decreased in high-Cd supply (> 5.0 mg L-1). Increasing Cd supply significantly enhanced shoot Cd concentration both in Suancaiwang and in New Beijing 3. With increasing in Cd supply from 0 to 10 mg L-1, the activity of superoxide dismutase (SOD) in New Beijing 3 decreased firstly and then increased under 5.0 mg L-1 Cd treatment. However, the activity of SOD in Suancaiwang increased firstly and then decreased with increasing Cd supply. Similarly, the activity of peroxidase (POD) and catalase (CAT) increased, or increased firstly and then decreased when the concentrations of Cd were relatively low. Significant increases in malondialdehyde (MDA) content were observed in the two cultivars after they were exposed to Cd.