Effect of silica and selenite foliar sprays on the uptake and transport of cadmium by rice under water management

The aim of the present study was to investigate the combined effect of foliar applications and water management on the uptake and transport of cadmium by rice. Field experiments were conducted to test the interactive effects of four foliar treatments and two water treatments, foliar treatments included deionized water (W1CK), a silica solution (W1Si), a sodium selenite solution (W1Se), and a 1:1 mixture of the silicon and selenium solutions (W1SS), two water treatments included conventional water management and continuous flooding during the late booting stage. Neither foliar spraying nor flooding had a significant effect on the growth or yield of brown rice. However, under conventional water management, the W1Si and W1Se treatments reduced the cadmium content of the brown rice by 71.7% and 61.9% (P< 0.01), respectively, when compared to the control treatment (W1CK), and the root-to-stem transfer coefficient decreased by 27.4% and 34.5%, respectively, whereas the stem-to-leaf transfer coefficient increased by 46.5% and 55.3%, respectively. Under continuous flooding during the late booting stage, the W2CK treatment reduced the cadmium content of the brown rice by 57.5% (P<0.01), when compared to W1CK treatment, whereas the W2Si, W2Se, and W2SS treatments had no significant effect (P>0.05). Even though the foliar Si and Se sprays and continuous flooding during the booting stage could both be used to prevent the migration of cadmium in rice plants and to reduce the accumulation of cadmium in brown rice, the combination of foliar treatment and water management failed to exhibit a synergistic effect on the cadmium content of brown rice.