Photosynthesis and antioxidant capacity in barley seedlings under the combined toxicity of cadmium and aluminum

Photosynthetic pigment content and photosynthetic activity, as well as the antioxidant capacity were estimated in barley seedlings after 10 or 20 d supplies of Al and Cd individual or combined in nutrient solution. The results showed that stress exposure strongly decreased photosynthetic pigment content and photosynthetic activity, as well as induced oxidative damage as evidenced by increased the activities of peroxidase (POD) and superoxide dismutase (SOD), and malonaldehyde (MDA) content in barley leaves. The most obvious response was found in plants exposed to higher levels of Cd (10 mu mol/L) or Al (90 mu mol/L) in the nutrient medium. Binary metal combinations generally aggravated photosynthesis reduction and induced more serious oxidative stress as compared with Al or Cd single treatments, and the most deleterious effects were observed in the combination of 90 mu mol/L Al+5 mu mol/L Cd.