Eco-Physiological Responses of Rice (Oryza sativa L.) Roots to Zinc, Chromium Stress

The plant could adapt to heavy metal conditions in soil to some extent. To study the adaptation process of rice plants under zinc, chromium stress, the effects of zinc, chromium in the soil on metabolism of rice ( Oryza sativa L.) roots were investigated by soil pot experiments at tillering, booting and filling stages of rice plants. In the experiment, with the augment of zinc or chromium concentrations, superoxide dismutase activity increased at both tillering and booting stages, and decreased at the filling stage, peroxidase activity increased at tillering stage, and decreased at booting and filling stages, and catalase activity decreased at the three growth stages. The increase of concentration of zinc or chromium augmented the content of soluble carbohydrate and the soluble protein content while reduced the content of soluble protein in rice roots at three growth stages. The growth of rice plants decreased with the increase of chromium and zinc concentration in soil, and the roots and shoot biomass and the rice grain weight reduced, but the root/shoot ratio (w/w) tended to increase with the augment of zinc or chromium concentration, which indicating that rice can improve its ecological adaptability under zinc or chromium stress.