Antimony accumulation and iron plaque formation at different growth stages of rice (Oryza sativa L.)

To better understand the Sb phytoavailability in rice, we studied Sb accumulation in rice (Zhongjiazao-17, widely cultivated in Hunan province) at different growth stages based on adding Sb^III and Sb^V to waterlogged soils in 10, 50 and 100 mg kg^-1 treatment levels. Proportional exogenous Sb^III and Sb^V remained in the soil solution after equilibration. In Sb^III treatments, the iron plaque (IP) amounts and Sb in rice roots sharply increased from tillering to jointing stages and then reduced at the following stages. However, in Sb^V treatments, they increased continuously from tillering to maturing stages. The accumulation trends of Sb in straws, ears and grains were consistent in Sb^III and Sb^V treatments, rising from tillering to jointing stages followed with reducing from jointing to flowering stages slightly, and rising again significantly from flowering to maturing stages. The Tfsoil-grain values in all the Sb treatments were low (0.77 × 10^-3-5.1 × 10^-3), However, when Sb in waterlogged soils were higher than 50 mg kg^-1, it could pose human health risk for residents.