Phytotoxicity of cadmium on peroxidation, superoxide dismutase, catalase and peroxidase activities in growing peanut (Arachis hypogaea L.)

A pot experiment treated with cadmium (Cd) was conducted to evaluate the physiological and yield responses of peanut to cadmium in different growth stages. The results indicated that the peanut treated with cadmium level of 12 mg/kg did not cause obvious visible toxic symptoms, while the antioxidant enzymes activities concluding superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) showed significant decrease in tested growth stages. The content of total chlorophyll decreased significantly in the growth stages (P < 0.05). The results indicated that Cd destroyed the balance of free radical metabolisms, which resulted in increasing malondialdehyde (MDA) content and the relative cell membrane permeability (RMP). The kernel yield and kernel rate per pot showed significant decrease under cadmium stress (P < 0.05). The varieties FengHua3, HuaYu20 and Luhua 12 showed more sensitive than the other varieties. The results indicated that the MDA, total chlorophyll content and RMP may be more sensitive or indicative than the others under Cadmium stress. Key words: Peanut (Arachis hypogaea L.), cadmium, phytotoxicity, physiological mechanism.