[Effects of Cd2+ on seedling growth and phytohormone contents of Glycine max].

A laboratory incubation experiment was conducted to study the effects of different Cd2+ concentrations on seedling growth and phytohormone contents of Glycine max through determining some physiological and biochemical indexes. The results showed as follows: (1) Different Cd2+ concentrations inhibited the synthesis of indoleacetic acid (IAA) and gibberellins (GA3) in roots and stimulated the synthesis of zeatin (Z) and abscisic acid (ABA) not only in roots but also in aerial parts of Glycine Max. Cd2+ stimulated the synthesis of IAA and GA3 in aerial parts at lower concentrations, but inhibited the synthesis of IAA and GA3 at higher concentrations. (2) Cd2+ stress for 84h increased the root vitality and the contents of chlorophyll a and b, but no significant difference was found in carotinoid contents compared with the control. (3) Cd2+ stress decreased POD activities and MAD contents atlower concentrations and increased POD activities and MAD contents at higher concentrations. With increasing Cd2+ concentrations, this increase became significant gradually. (4) Cd2+ stress with lower concentrations stimulated the physiological activity of Glycine max seedling in a short time. When Cd2+ concentration was 0.50 mg/L, the root vitality, IAA and GA3 contents of Glycine max were the highest, and POD activity was the lowest.