Effects of selenium( Se) on the physiological characteristics,element contents,uptake and transportation of Cd in spinach under Cd stress

Pot experiments were performed to investigate the physiological mechanisms of selenium( Se) mitigation of Cadmium( Cd) toxicity in spinach. The effects of different concentration selenium( Se)( 0,0. 5,2. 0 and 4. 0 mg·L- 1) on the physiological characteristics,element contents and uptake and transportation of Cd in spinach under different concentrations of Cd( 0. 5 and 2. 0 mg·kg- 1) stress were studied. The results showed that different concentrations of Se dramatically depressed malondialdehyde( MDA) accumulation. With the optimal Se concentration,the contents of MDA were 53. 93% and 41. 79% of those under single stress of Cd in two concentrations. Different concentrations of Se alleviated the inhibitory effects of Cd on the shoots and roots of spinach,and the fresh weight and dry mass of hoots and roots were 1. 13,1. 29,1. 31,1. 37 and 1. 78,2. 09,3. 03,4. 36 times those under single stress of Cd in two concentrations,respectively,with the optimal Se concentrations. Exogenous Se markedly increased the chlorophyll content,the content of chlorophyll was 1. 51 and 1. 35 times that under single stress of Cd in two concentrations,respectively,when the exogenous Se concentration were optimal. The superoxide dismutase( SOD) activities increased about 36. 0% and 42. 8%,respectively,compared with the single stress of Cd in two concentrations. Exogenous Se increased K,Na,Ca and Mg contents in the shoots and roots by different degrees. Under the application of Se,the uptake,bioaccumulation and translocation of Cd were effectively inhibited,and the Cd concentration in shoots and roots significantly decreased to 65. 77%,75. 92% and 46. 11%,70. 01% of those under single stress of Cd in two concentrations. Results indicated that Se application could effectively alleviate Cd- induced toxicity in spinach. The optimal Se concentration was 2. 0 mg·L- 1and 4. 0 mg·L- 1.