Effects of nano-selenium and sodium selenite application on cadmium accumulation in rice planting in cadmium contaminated soil

【Objective】The effects of exogenous nano-selenium and sodium selenite on cadmium absorption, transport and accumulation in rice in cadmium contaminated soil were studied to provide scientific reference for the regulation of cadmium contaminated farmland and the safe production of rice.【Method】In this paper, pot experiment was carried out, no exogenous selenium was added as control(CK), and four treatments were set up, 0.5 and 2.5 mg/kg of nano-selenium, 0.5 and 2.5 mg/kg of sodium selenite(in terms of selenium) were applied per kilogram of soil, respectively. The content of chlorophyll in rice leaves was measured at the grain filling stage, the photosynthetic index of rice was measured before harvest, and the biomass and yield of rice and rice root, stem and leaf were measured after harvest. The content of cadmium in brown rice and the form of cadmium in soil were measured. The distribution rate of cadmium in different parts of rice and the migration rate of cadmium in rice were calculated.【Result】Compared with CK, nano-selenium and sodium selenite treatments significantly increased SPAD value and photosynthetic rate of rice flag leaves at harvest stage(P<0.05, the same below);except 0.5 mg/kg nano-selenium treatment had no significant effect on rice yield(P>0.05), the other treatments significantly promoted the yield of rice. Both exogenous nano-selenium and sodium selenite treatments reduced the content of soluble exchangeable cadmium in soil, and the treatment of applying 0.5 mg/kg Se derived from nano-selenium of soil had the most significant effect, which reduced the content of soluble exchangeable cadmium by 16.0%. The treatments of exogenous nano-selenium and sodium selenite could reduce the absorption, transport and accumulation of cadmium in rice. Cadmium uptake in rice roots, cadmium content in rice grains, and the transfer rate of cadmium from root to stem and leaf treated with applying 2.5 mg/kg selenium derived from nano-selenium of soil decreased significantly by 26.8%, 32.7% and 42.7%, respectively.【Conclusion】The application of nano-selenium and sodium selenite in cadmium contaminated soil can effectively reduce the availability of cadmium in cadmium contaminated soil, and reduce the absorption, transportation and accumulation of cadmium in rice. The application of 2.5 mg/kg of nano-selenium per kilogram of soil has a better effect on preventing the accumulation of cadmium in rice, which can be used as a recommended technique for safe production of rice in cadmium contaminated areas.