Effect of Elevated Atmospheric Ozone Concentration on the Bioavailability of Cu in Soil and Oxidative Stress of Cu in Wheat(Triticum aestivum L. cv. Yangmai14)

Using a Free Air Concentration Enrichment (FACE)system, we studied the effects of elevated O3 concentrations on bioaccumu- lation of Cu in wheat plant and its oxidative stress to wheat plant in pot. At elevated O3 concentration, both concentration of available Cu in soil and uptake of Cu by wheat shoots increased. The malondialdehyde(MDA)contents of wheat plants grown in Cu-contaminated soil at ele- vated O3 concentrations were significantly higher than the control. At the wheat mid-tillering growth stage, we observed an increased activity of superoxide dismutase(SOD, EC 1.12.1.1)and phenol peroxidase(POD, EC 1.11.1.7)in the Cu and elevated O3 treatments. However, activi- ties of these antioxidant enzymes were induced by Cu and elevated O3 treatments at the wheat panicle initiation growth stage, and inhibited over the exposure time. It can be concluded that elevated O3 concentration can enhance Cu bioavailability and toxicity to wheat, which results in increased oxidative stresses and damage to the self-protection mechanisms of wheat plant.