Changes in physiological parameters and some antioxidant enzymes activities of soybean (Glycine max L. Merr.) leaves under cadmium and salt stress

The combined effect of cadmium stress (0,5 mM Cd(NO3)2) and salt stress (100 mM NaCl) on growth, lipid peroxidation and activities of some antioxidant enzymes were studied in soybean (Glycine max L. Merr.) leaves. Shoot lenghts were not changed under all groups. But fresh and dry weight were decreased under salt treatment alone and Cd treatment alone. The decrease was more in the group of combined of Cd and salt treatment. Although APX activity increased under salt treatment alone and combined of Cd and salt treatment, GR activity increased under Cd treatment alone and combined of Cd and salt treatment. Nevertheless DHAR activity increased only in combined of Cd and salt stress. MDA content increased under all groups but it was more in the combined of Cd and salt stress which indicates that salinity is more harmful with cadmium stress in soybean plants. Thus, it was concluded that some of antioxidant enzymes (APX, GR, DHAR) increased their activity under combined of Cd and salt treatment but they were not efficient to protect oxidative damage from soybean plants by alleviating the lipid peroxidation.