Effects of Phosphate On the Formation of Iron Hydroxides On the Surface of Rice Root.

In rice paddy soil, the reductive dissolution of Fe(III) oxides results in the release of Fe(II) into soil solution. Because of the oxic condition on the surface of rice root, Fe(II) is oxidized to Fe(III) and the precipitation of Fe(III) subsequently occurs. In this study, the effects of phosphate on the formation of iron hydroxides on the surface of rice root were investigated. Rice plants were grown in hydroponic solutions with different phosphate concentrations and Fe²⁺/Fe³⁺ concentrations. The mineral compositions on the roots of rice plants grown under different conditions were determined using X-ray diffraction and X-ray absorption spectroscopy. The contents of P and Fe on the rice roots were analyzed. The results may provide information for understanding the roles of iron plaque on the uptakes of P and Fe by rice root.