Resistance to Cadmium Stress of Rice Seedling Enhanced by Exogenous Salicylic Acid

To investigate whether tolerance to cadmium(Cd) stress of rice seedlings could be enhanced or not by exogenous salicylic acid(SA),rice seedlings were grown in half concentration of Kimura Solution B,CdCl2 500 μmol/L and 300 μmol/L SA(SA1),or 500 μmol/L SA(SA2) was added to the solution,and the free Salicylic acid as control(CK).Under Cd stress condition,the activities of superoxide dismutase(SOD),catalase(CAT),peroxidase(POD),chlorophyll content and the photosynthesis rate of rice leaves were greatly decreased,and content of MDA in rice leaves were greatly increased.But after SA was added to the nutrition solution with Cd,the activities of SOD,CAT and POD in rice leaves were greater than that with Cd stress,and the rate of reactive oxygen production,the content of H2O2 and MDA was decreased,the content of chlorophyll greatly decreased.All these results indicated that the tolerance to cadmium stress of rice seedlings could be increased by exogenous SA through its effects on the activities of antioxidant enzyme.