Physiological responses of maize to elemental sulphur and cadmium stress

The physiological response to application of elemental sulphur (S) and cadmium (Cd) of maize (Zea mays L.) grown for 60 days in pot soil was studied. The S was added into the soil with 2 rates (0 and 50 mmol/kg) and Cd was added in solution in 4 rates (0, 20, 50, 100 mg/kg). All the S and Cd were added before planting. Shoot biomass decreased with the application of Cd to the soil whether S was applied or not. The application of S and Cd to soil led to an increasing accumulation of Cd in the shoots of maize. The concentration of chlorophyll was reduced significantly in Cd-treated plants with or without supplementary S. The content of malondialdehyde (MDA) was increased significantly in treatments with S and Cd, compared to the control. The activity of peroxidases (POD) was increased but catalase (CAT) was decreased in plants treated with Cd, again with or without S, in comparison with control. POD and CAT activities decreased in all the Cd treated plants with S, as compared to the plants without S. The results suggest that Cd reduces the crop growth, concentration of chlorophyll and activity of CAT, but increases the content of MDA and activity of POD. S supplies decrease the content of MDA, activities of POD and CAT, as compared to zero S supplies at the same rate of Cd application.