Interactive effects of selenium and antimony on the uptake of selenium, antimony and essential elements in paddy-rice

Selenium (Se) can be used to detoxify antimony (Sb); however, the associated mechanisms are not fully understood, in particular, the responses of essential elements to co-exposure to Se and Sb. To resolve the above question, two nested hydroponic experiments based on a two-factor, five-level central composite design, were performed using a conventional indica rice (Fengmeizhan). The results showed that when the Se concentration was fixed at 0.8 mg L-1, the addition of Sb, even at concentrations as low as 2.171 mg L-1, could produce damages to this plant and significantly reduce both the aboveground and root biomasses, suggesting a high toxicity of Sb to this plant. However, when the Sb concentration was fixed at 5 mg L-1, Se eliminated the negative effects of Sb on the aboveground growth of paddy-rice but did not noticeably affect the root biomass, suggesting a beneficial role of Se in conferring resistance to Sb toxicity in paddy-rice. Interestingly, when the Se concentration was fixed at 0.8 mg L-1, the addition of Sb caused a consistent decrease in the Se concentration in the roots but a slight increase in the Se concentration in the aboveground, suggesting a dual effect of Sb on Se uptake. Furthermore, the addition of Sb could counterbalance the negative effects of 0.8 mg L-1 Se on the uptake of most of the tested essential elements, significantly increased their concentrations in the different tissues of this plant. The Se-mediated alleviation of Sb toxicity could be closely connected with (1) the direct inhibition of Sb uptake; and (2) the uptake regulation of some essential elements, such as calcium (Ca), magnesium (Mg) and potassium (K). This study contributes to the understanding of both the the interactions between Se and Sb and their effects on the uptake of essential elements in paddy-rice