Influence of iron plaque and cultivars on antimony uptake by and translocation in rice (Oryza sativa L.) seedlings exposed to Sb(III) or Sb(V)

Background and Aims: Characteristically baseline levels of Sb in the environment are low, but problematic local elevation trends arise from anthropogenic activities such as mining and incineration. Arsenic (analog of Sb) accumulation by rice can be reduced by iron (Fe) plaque. A hydroponic experiment was conducted to investigate whether Fe plaque could reduce the uptake and translocation of different Sb species in different rice cultivars. Methods: After Fe plaque on rice roots was induced in solution containing 0, 0.2, 0.4, 0.7, 1.2, 2.0 mM Fe ²⁺ for 24 h, seedlings were transferred into nutrient solution with 20 μM Sb(V) or Sb(III) for 3 d. Results: About 60-80% (Sb(III) treatment) and 40-60% (Sb(V) treatment) of the total Sb accumulated in Fe plaque. There was a significant correlation between the concentrations of Sb and Fe on the root surface. A similar relationship was observed in roots and shoots. Cultivar (Jiahua 1) formed the most Fe plaque, had the highest Fe associated Sb sequestration but the lowest Sb concentration in the root interior. Conclusions: Fe plaque may act as a 'buffer' for Sb(V) and Sb(III) in the rhizosphere, and cultivars played an important role in the different species Sb uptake and translocation.