Effects of Silicon Application on Uptake of Arsenic and Phosphorus and Formation of Iron Plaque in Rice Seedlings Grown in an Arsenic-Contaminated Soil

Silicon (Si) plays important roles in improving rice growth and mitigating rice arsenic (As) uptake. In the present study, a pot experiment was carried out to investigate effects of Si application on uptake of As and phosphorus (P) and formation of iron (Fe) plaque on root surface of two rice cultivars (Zhendao 10 and Nanjing 44) grown in a high As-contaminated soil. The results showed that dry weights of shoots and roots for both rice cultivars didn't significantly varied under low Si level, but significantly increased for Zhendao 10, while decreased for Nanjing 44 under high Si level (p<0.05). As concentrations in shoots and roots of Nanjing 44 significantly decreased for low Si level, while significantly increased for high Si level (p<0.05). Different from Nanjing 44, effect of Si application on As concentrations in the plants of Zhendao 10 wasn't significant (p>0.05). Si significantly increased concentrations of P in shoots and roots of both rice cultivars (p<0.05). However, Si didn't significantly affect formation of Fe plaque on root surface. These results suggest that the effects of Si application on rice growth and As uptake in As-contaminated soils may depend on type of rice cultivar and Si application level. Rice cultivar and Si application rate should be considered when Si application is used to mitigate As accumulation in rice.