Effects of cadmium stress on antioxidant enzyme system and absorption of mineral elements in maize seedlings.

The effects of different concentrations of Cd2(+10-6,10-5,10-4 mol·L-1)on antioxidant enzyme system,and malondialdehyde content in maize seedlings were investigated using water culture method,as well as the Cd accumulation and its effects on mineral element uptake by ICP-AES.The results indicated that the content of MDA was not affected significantly when maize seedlings were stressed by 10-6 and 10-5 mol·L-1 of Cd2+ in comparison with the control,and increased significantly by 10-4 mol·L-1 of Cd2(+P0.05).The activities of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT)in maize seedlings increased at the early days,and decreased with prolonging duration of Cd treatment except for SOD and CAT in leaves,and decreased the most at the highest concentration.Cadmium absorbed by the seedlings accumulated mostly in roots,and the Cd2+ stress affected absorption of Fe,Cu,Zn and Mg.The contents of Fe,Cu,Zn of leaves were not affected significantly at 10-6 and 10-5 mol·L-1 of Cd2+.Cadmium stimulated the absorption of Fe,Cu and Zn in roots,especially Fe in roots.The content of Mg in roots and leaves was stimulated by lower concentration of Cd2+ and inhibited by higher concentration of Cd2+.The mechanism of Cd2+ toxicity was briefly discussed in the end.