The aim of this study is to examine the effects of Cd on the growth, oxidative stress, and antioxidative enzymes as well as on photosynthetic performance of early wheat seedlings. The possible mechanisms of wheat seedlings, response to Cd stress involving free radical metabolism and antioxidant changes are also discussed. Effects of cadmium (Cd) on seed germination, seedling biomass, root length and shoot height, Cd uptake, amylase activity and the activities of antioxidative enzymes as well as photosynthetic activities, soluble protein and malondialdehyde (MDA) concentrations in wheat seedlings were investigated. Seedlings were exposed to different CdCl2 concentrations for 7 days. Seed germination and seedling biomass and root and shoot elongation decreased with increasing of Cd. Root was the most sensitive parameter. Seedlings took more Cd up with increasing Cd in the test solutions. Fluorescence measurements showed that F0 was slimly increased but FM was decreased progressively with increasing Cd. Total amylolytic, α-amylase and β-amylase activities were depressed by the higher Cd concentrations. A significant increase of MDA contents and peroxidase POD and superoxide dismutase SOD activity in Seedlings were observed with increasing concentration of Cd. The MDA content was linearly and positively correlated with seed germination frequency, biomass increment, root length and shoot height elongation, suggesting that MDA may be useful as a biological indicator of Cd toxicity in wheat.
