Effect of silicate on the growth and arsenate uptake by rice (Oryza sativa L.) seedlings in solution culture

A solution culture experiment was conducted to investigate the effect of silicate on the yield and arsenate uptake by rice. Rice seedlings (Oryia sativa L. cv. Weiyou 77) were cultured in modified Hoagland nutrient solution containing three arsenate levels (0, 0.5 and 1.0 mg L-1 As) and four silicate levels (0, 14, 28 and 56 mg U 1 Si). Addition of Si significantly increased shoot dry weight (P = 0.001) but had little effect on root dry weight (P = 0.43). Addition of As had no significant effect on shoot dry weight (P = 0.43) but significantly increased root dry weight (P = 0.01). Silicon concentrations in shoots and roots increased proportionally to increasing amounts of externally supplied Si (P < 0.001). The presence of As in the nutrient solution had little effect on shoot Si concentration (P = 0.16) but significantly decreased root Si concentration (P = 0.005). Increasing external Si concentration significantly decreased shoot and root As concentrations and total As uptake by rice seedlings (P < 0.001). In addition, Si significantly decreased shoot P concentration and shoot P uptake (P < 0.001). The data clearly demonstrate a beneficial effect of Si on the growth of rice seedlings. Addition of Si to the growth medium also inhibited the uptake of arsenate and phosphate by the rice seedlings.