Effects of root oxidation ability and P on As mobility and bioavailability in rice

The effects of root oxidization ability and P fertilization on As mobility in soils, and subsequently As uptake, translocation and speciation in rice plants were investigated. Results show that root oxidation significantly influences As mobility in rhizoshphere. Genotype TD71 with higher radial oxygen loss (ROL) induces more Fe plaque formation and sequesters more As and P in iron plaque and rhizoshphere soil, leading to the reduction of As accumulation in rice plants. Additionally, P addition mobilizes As in soil solution, and increases As accumulation in rice plants. Arsenic speciation results show that the majority of As species in husks detected is inorganic As, accounting for 82%–93% of the total As, while in grains the majority of As is inorganic As and dimethyl arsenic (DMA), with DMA accounting for 33%–64% of the total As. The fraction of inorganic As decreases while fraction of DMA increases, with increasing As and P concentrations. The study further elucidates the mechanisms involved in effects of ROL on As tolerance and accumulation in rice.