Effect of Silicon on Arsenic Concentration and Speciation in Different Rice Tissues

Rice is a major source of inorganic arsenic (As) exposure for billions of people worldwide. Therefore, strategies to reduce As accumulation in rice should be adopted. Silicon (Si) application can effectively mitigate As accumulation in rice. In this study, a pot experiment was performed to investigate the effect of Si on As speciation and distribution in different rice tissues. The results showed that Si addition significantly increased As and Si concentrations in soil solution and Si concentration in iron plaque formed around rice root surface, whereas As in the iron plaque was significantly decreased. Total As concentrations in the stem, leaf, husk, and brown rice were remarkably decreased by 51.9%, 31.9%, 33.8%, and 24.1%, respectively, after Si addition, and inorganic As concentrations were reduced by 52.3%, 35.5%, 50.1%, and 20.1%, respectively. Moreover, both dimethylarsinic acid concentration and percentage in rice grain were significantly elevated by Si application. Therefore, Si application is promising as a way to mitigate inorganic As accumulation in rice and to reduce consumer health risk.