Lead (Pb) accumulation in rice grains has been identified as a potential threat to human health. Our study investigated the effects of varied rates of selenite fertilization (0, 0.5 and 1.0 mg·kg-1) on the dynamics of Pb in soil solutions, and its uptake and translocation by rice under different water management scenarios (aerobic and flooded) in pot experiments. Plants were harvested at seedling stage and at maturity to determine the Pb contents, and soil solutions were extracted during the growing season to monitor the Pb dynamics. Results showed that flooding the soil significantly increased Pb concentrations in DCB extracts and rice roots both at seedling stage and maturity. Root Pb contents in flooded treatments were 4.2-8.5 and 1.4-1.5 times higher than those under aerobic conditions at rice seedling stage and maturity. Flooding also decreased the percentage of Pb in rice shoots. The Pb content in soil solutions, rice seedlings, rice roots and stems at maturity were significantly decreased by selenite additions. Relative to the control treatment, selenite additions decreased the rice root Pb contents by 5.4%-24.3% and 2.7%-61.7% under flooding and aerobic conditions at seedling stage, respectively; while decreased Pb in rice root by 56.1%-64.1% and 53.8%-63.2% respectively, at maturity. No significant differences existed in grain Pb levels among the treatments. Results demonstrated that water management regimes and selenite additions affected Pb uptake by rice roots significantly, but had no significant influence on Pb accumulation in rice grains.
Keywords: accumulation; lead; rice; selenite; uptake; water management.