Effect of Exogenous Selenium on Activities of Antioxidant Enzymes, Cadmium Accumulation and Chemical Forms of Cadmium in Tomatoes

Pot experiment was conducted to investigated the effect of Na2SeO3 treatment at concentrations of 0, 0.5 and 1.0 mg.L-1 on biomass, and activities of antioxidant enzymes and chemical forms and accumulation of Cd in two tomato varieties (variety 4641 (V4641) with high Cd enriched variety and Yu powder 109 (YP109) with low Cd enriched variety) when exposed to cadmium (Cd) in soil at the concentration of 20 mg.kg(-1). The results showed that foliar spray of selenium (Se) (<= 1.0 mg.L-1) increased the dry weights of roots, fruits, and leaves in the two varieties by 1.7%-48.8%, 13.1%-37.5% and 5.4%-47.2%, respectively. The foliar spray of Se significantly increased SOD activity, and reduce CAT and POD activities in both tomato varieties. The Cd proportion of extractable form (F-NaCl), residual Cd (F-R) and HCl extractable Cd (F-HCl) with low activity accounted for 65.5% of total extractable Cd. The application of Se decreased the contents of total extractable Cd and concentrations of different chemical forms Cd in fruits of both tomato varieties. The foliar spray of Na2SeO3 reduced Cd concentrations in leaves, stems, roots and fruits in both tomato varieties by 7.3-41.9%, 9.8-30.9%, 24.5-48.5% and 14.4-37.1%. The concentration of Cd and the accumulation of Cd in fruits of V4641 were higher than in fruits of YP 109 in the present of Na2SeO3 when exposed to Cd in soil at the concentration of 20 mg.kg(-1). Fruits of YP109 are relatively safer for human body than those of V4641 in Cd-contaminated soil. (C) 2017 Friends Science Publishers