Effects of compound pollution of Zn and Cr on antioxidant enzyme activity of rice (Oryza sativa L.) roots

In order to study the adaptation processes of rice plants under compound pollution of heavy metals, two heavy metals (Zn and Cr) which are common pollution elements in Chengdu Plain were added in the soil, and planted rice plants in the pots in this experiment. The results showed that three antioxidant enzymes (superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT)) activities of rice roots were showen in different trends at different growth stages of rice plants with increasing concentration of Zn or Cr. At tillering stage of rice plants, SOD and POD activities of rice roots had a trend of reducing first and increasing afterwards with increasing concentration of Cr, and had an increasing trend with increasing concentration of Zn, and CAT activity of rice roots had a reducing trend with increasing concentrations of Zn and Cr. At booting stage of rice plants, SOD activity of rice roots had a trend of reducing first and increasing afterwards with increasing concentrations of Zn and Cr, but POD and CAT activities of rice roots had a reducing trend. At filling stage of rice plants, SOD, POD and CAT activities of rice roots had a trend of reducing with increasing concentrations of Zn and Cr. Grain yield of rice plants had a reducing trend with increasing concentrations of Zn and Cr. The concentrations of Zn and Cr had compound pollution effects on grain yield of rice plants, and had highly significant linear regression with it. These indicated that rice plants could adjust its physiological metabolism to improve the ecological adaptability to compound pollution of Zn and Cr, and it provides theoretical basis for cultivating rice varieties which can grow in heavy metal contaminated areas well.