The effect of Zn and Cd on growth and antioxidant enzymes activity of Suaeda heteroptera Kitagawa
重金属Zn和Cd对翅碱蓬生长及抗氧化酶系统的影响

The effects of heavy metals Zn and Cd on germination, height, weight, production of superoxide anion free radical (O2-·) and hydrogen peroxide (H2O2), and antioxidant enzyme activities of Suaeda heteroptera Kitagawa were studied. Glasswort Suaeda heteroptera Kitagawa was exposed to different Zn and Cd concentrations in order to evaluate the responses of the plant to heavy metal stress. Zn and Cd promoted the production of superoxide anion free radicals. The plant had tolerance threshold of 100 mg·kg-1 for Zn showing similar germination rate, height and weight in the control group in Zn concentration of under 100 mg·kg-1. In Zn concentration of over 100 mg·kg-1, however, the inhibition of growth and the antioxidant enzyme activities were found to some extent in the plant, superoxide dismutase (SOD) and peroxidase (POD) responding rapidly but catalase (CAT) responding slowly. The plant had low resistance to Cd, showing severe damage even at Cd concentration of over 0.4 mg·kg-1. At this dose of Cd, the growth was hindered and the antioxidant enzymes activity decreased. The synergy effect of Zn and Cd was observed at Zn concentration of 200 mg·kg-1 and Cd concentration of 0.2 mg·kg-1 where the germination rate of the experimental plants was found to be only 50.5% of the control group and the plant weight 49.2% of the of the control group. The SOD and CAT were both inactivated at Zn concentration of 200 mg·kg-1 and Cd concentration of 0.2 mg·kg-1 in the 50 day experiment. The findings will provide a reference for halophytes toxicology study in contaminated coastal beach.