Effects of Silicon and Iron Application on Arsenic Absorption and Physiological Characteristics of Rice ( Oryza sativa L.)

This study investigated the effects of silicon and iron on arsenic absorption, as well as the changes in the physiological indices of rice under arsenic stress and how these indices respond to silicon and iron. We found that application of silicon and iron reduces arsenic absorption in rice; co-application of silicon and iron reduced arsenic content by 25.6%–27.4%. The antioxidant enzyme activities of rice treated with silicon and iron were significantly lower than those of untreated rice, with the biggest decreases observed under co-application treatments. Iron significantly increased osmoregulatory substances, while silicon increased soluble sugar; Si1Fe1 treatment (containing 1 mM silicon, 0.1 mM iron) had the highest content of osmoregulatory substances except CK. Membership function analysis suggested that applying silicon and iron alone alleviates the stress condition in rice, with the lowest stresses observed under Si1Fe1 treatment. These results show that silicon and iron co-application significantly inhibits arsenic uptake in rice, decreases the antioxidant enzymes activity, while non-enzymatic substances in rice can be regulated to further alleviate arsenic stress.