[Effects of Zn on the growth, Cd accumulation and physiological resistance of Iris lactea var. chinensis under Cd stress].

A solution culture experiment was conducted to examine the effects of Zn (1-100 mg x L(-1)) on the growth, Cd accumulation, and antioxidant enzyme activities of Iris lactea var. chinensis under Cd stress (10 mg x L(-1)). The results showed that after the addition of Zn, the Cd content changed a little in shoots, but increased significantly in roots, with a trend of rising first and dropping then. When treated with 1 mg Zn x L(-1), the Cd content in roots was the highest, being 51.4% higher than the control. When the Zn concentration was higher than 1 mg x L(-1), the Cd content in roots decreased to some extent, but was still higher than the control. Low concentration (1-10 mg x L(-1)) Zn increased the shoot biomass and leaf chlorophyll content, but decreased the malondialdehyde (MDA) content. At 10 mg Zn x L(-1), the chlorophyll a and b contents went up to the maximum, being 5.21% and 22.27% higher than the control, respectively, while the MDA content decreased by 25.46%, indicating that low concentration Zn could alleviate Cd damage. With increasing Zn concentration, the alleviation effect of Zn on Cd damage decreased gradually. When the Zn concentration was 100 mg x L(-1), I. lactea var. chinensis was damaged most seriously, with the biomass and chlorophyll content reduced and MDA content increased significantly. Within the ranges of test Cd and Zn concentrations, the activities of superoxide dismutase (SOD) and peroxidase (POD) had an increasing trend, suggesting that SOD and POD played an important antioxidant protective role for Cd or Zn-Cd stressed I. lactea var. chinensis.