Uptake and Accumulation Characteristics of Arsenic and Iron Plaque in Rice at Different Growth Stages

Abstract

Arsenic (As) uptake by rice plants and its toxicity to human beings have caused worldwide concerns. Investigating the characteristics of As accumulation in rice in relation to root surface iron plaque during the whole growth of rice would provide important information for devising measures to mitigate rice As uptake in As-polluted areas. Uptake and accumulation characteristics of As in rice at different growth stages as well as iron plaque on rice root surfaces were investigated in a pot culture experiment in a greenhouse. The results showed that As concentrations in roots, stems, and leaves increased with rice growth, while As concentration in spikelets decreased with grain development: 53.63% of As content in leaves, 61.51% in spikelets, and 82.09% in stems were found at both the jointing and booting stages, which suggested that the two stages were the key stages of As uptake. Root surface iron plaque at different growth stages was extracted by DCB (dithionite-citrate-bicarbonate). DCB-extractable iron (Fe) and DCB-extractable As were significantly increased with rice growth (P < 0.001), and there was a significant positive correlation between DCB-extractable Fe and As (P < 0.001), indicating that iron plaque was very important to sequester As on rice root surfaces.