[Effect of Three Foliar Inhibitors on Accumulation of Cd and As in Rice Grains].

Abstract

This study investigated the impact of single and combined applications of three foliar inhibitors on the accumulation of cadmium （Cd） and arsenic （As） in rice grains. Two rice varieties, Songyazao 1 （for early rice） and Wuxiang Youyue （for late rice）, were selected for this experiment. We established nine treatments using a pot experiment method, including a control （CK） treated with no foliar inhibitor and three individual foliar inhibitors： cysteine （L-Cys）, potassium sulfide （K₂S）, and dipotassium hydrogen phosphate （K₂HPO₄）. We then combined the applications of two foliar inhibitors： L-Cys with low/high concentrations of K₂S, L-Cys with low/high concentrations of K₂HPO₄, and K₂S with a low concentration of K₂HPO₄. The results showed that the single and combined applications of foliar inhibitors reduced Cd and As concentrations in rice grains. The Cd content in brown rice treated with L-Cys and K₂S/K₂HPO₄ was reduced below the standard limit for food safety of 0.20 mg·kg^-1. Compared to the CK, the content of inorganic arsenic （IAs） in early and late rice decreased by 4.68%-56.75% and 2.84%-16.91%, respectively. Foliar inhibitors applied individually or in combinations facilitated the transport of Cd and As from the stem to the leaf while inhibiting their transport from the leaf to the rice grain. This resulted in the sequestration of Cd and As within the leaf cell wall, ultimately reducing the content of these elements in rice grains. Among the combination treatments, the application of L-Cys and high-concentration K₂S achieved the best results. The Cd content in early and late rice decreased by 37.64% and 26.37%, respectively, falling below 0.20 mg·kg^-1. The IAs content in early and late rice was reduced to 0.10 mg·kg^-1 （below 0.20 mg·kg^-1） and 0.24 mg·kg^-1, respectively. This study provides a valuable theoretical foundation and empirical data to support the achievement of safe rice production practices.