Physiological and biochemical properties of wheat seedlings under cadmium stress.

Two kinds of wheat,cv.'Xihan 2' and 'Ningchun 4',were employed to study the changes of physiological and biochemical properties under different cadmium nitrate concentration treatments,such as chlorophyll content,antioxidant enzyme activities and osmotic regulations.The results showed that the amount of chlorophyll a,chlorophyll b and total chlorophyll in seedlings of the two cultivars exposed to cadmium nitrate was all decreased,and the destroy to chlorophyll b was more serious than to chlorophyll a in 'Xihan 2' seedlings under higher Cd stress.Compared to the control,different cadmium nitrate concentration enhanced the activities of catalase,peroxidase and ascorbate peroxidase,but no significant changes in soluble sugar content.In addition,concentration-dependent increased proline level was observed in 'Ningchun 4' with different concentration of Cd(NO3)2.In conclusion,Cd treatment resulted in destruction to photosynthetic pigments at different degrees,but induced the higher activities of antioxidant enzymes in two wheat cultivars;and also,the stronger effect of osmotic regulations caused by proline accumulation exhitibited in 'Ningchun 4' under Cd stress.Thus,no significant oxidative damage was observed in wheat seedlings exposed to cadmium nitrate.