Oxidative stress induced by copper in sunflower plants.

The toxic effect of copper was evaluated in sunflower plants by means of root elongation, lipid peroxidation and antioxidative enzyme activities. Plants were grown under controlled environmental conditions in hydroponic culture for two weeks and exposed to different copper concentrations for an additional week. Determinations were performed in both roots and leaves. From the results of the root elongation test, a copper concentration of 10 microM was found to be toxic for sunflower plants causing lipid peroxidation and, thus, oxidative stress. Antioxidative enzymes (peroxidase and superoxide dismutase) responded at lower, nontoxic copper concentrations.