Effect of Cadmium stress on the growth traits and cell protective enzyme system of vegetable soybean

The vegetable soybean variety Texuan 75 was selected as experimental material to study the effects of heavy metal Cadmium(Cd) stress on the growth and protective enzyme systems.The results showed that:(1) Compared with control(without Cd),beans under different concentration Cd2+ stress demonstrated various degrees of poisoning symptoms,and had lower fresh weight of both under and above ground parts;(2) When stressed with Cd2+ concentration ≤1 mg·L-1,activities of soybean plant antioxidant system enzymes were stimulated,membrane lipid oxidation was inhibited,its SOD,POD and CAT activities increased with Cd concentration increasing to prontect the cell from being damaged to some degrees;(3) MDA content of plant decreased significantly comparing with the control due to activities of soybean plant antioxidant system enzymes being stimulated under Cd stress;while MDA content increased significantly when Cd2+ concentration attained 2 mg·L-1 due to exceeding ability of plant antioxidant system enzymes against oxidation,which in turn resulted in plants being seriously poisoned,a number of growth indicators such as plant fresh weight,leaf chlorophyll and root vigour decreased significantly.