PHYSIOLOGICAL RESPONSES OF FOUR PEANUT CULTIVARS TO CADMIUM STRESS

Cadmium (Cd) can stress plants by affecting various physiological functions. However, little information is available about the variation in Cd tolerance among peanut (Arachis hypogaea L.) cultivars and its underlying physiological regulation mechanisms. In the present study, a hydroponic pot experiment was conducted to investigate physiological changes among four peanut cultivars exposed to 0, 5,10, 20, 40, and 80 mu mol L-1 CdCl2. The results showed that Cd stress significantly decreased plant growth, leaf chlorophyll contents and increased the malondialdehyde (MDA) content in leaves of four peanut cultivars. Compared with related controls, exposure to 80 mu mol/L Cd reduced root and shoot biomass by 35.7-69.2 and 18.6-62.1% for the four cultivars, respectively. Moreover, significant variations were observed in root and shoot biomass, leaf chlorophyll contents, MDA contents as well as the antioxidant enzymes activity among peanut cultivars at the six Cd levels. Among four peanut cultivars, BS1106 displayed the lowest root and shoot biomass, leaf chlorophyll contents and antioxidant enzyme activities, but the highest MDA and leave membrane permeability. These results indicate that BS1106 are less tolerant to Cd stress than the other three peanut cultivars, which is probably related to bad-coordinated antioxidant defense mechanisms.