Effect Of Selenium Application On Cadmium Accumulation And In Rice(Oryza Sativa)

Cadmium(Cadmium,Cd)is strong toxicity for organisms,which could could easily enter to the human body through food chain and resulting hazardsfor human health.As the main food crop in Asia,rice plays an important role in agricultural production.However,rice polluted by Cd has been becoming more and more serious.Therefore,reduce Cd accumulation in rice is an urgent task.Selenium(Se)is one of the essential nutrients in the human body.Se could affect the absorption and accumulation of heavy metals in crops.The effects of sodium selenite and nano-selenium on the absorption of cadmium and selenium in rice seedlings were studied by hydroponics experiment and pot experiment.The effects of soil application and foliar spraying sodium selenite and nano-selenium on the accumulation and distribution of Cd and Se in various organs and grains of rice were studied.The effects of Se on the distribution and accumulation of cadmium in rice were revealed,and the technical measures for Cd pollution and Cd pollution in the rice field were discussed,which provided a theoretical basis and technical support for solving the current problem of cadmium pollution in rice.The main results are as follows:1.A pot experiment was conducted to study the effects of different application of sodium selenite and nano-selenium on the growth,accumulation and distribution of Cd in rice grown cultured at Cd-contaminated soil.The results showed that the exogenous selenium could promote the growth and yield of rice under high Cd-contaminated soil.Under Cd-contaminated soil condition,compared with the control,foliar application of 0.5 mg/kg nano-selenium,foliar application of 1mmol/L nano-selenium and sodium selenite increased the yield of rice by 23.89%,26.30%and 24.24%,in which foliar application of 1mmol/L sodium selenite promoted highest the rice yield.The order of Cd content in various organs of rice was root>stem>leaf>brown rice grain>white rice grain.foliar application of sodium selenite and nano-selenium increased the distribution ratio of root Cd,significantly inhibited the transport of Cd fiom root to shoot,and reduced the accumulation of Cd in shoot.Under Cd-contaminated soil,the contents of sodium selenite and nano-selenium in different concentrations of leaf spraying and soil application could significantly reduce the Cd content of brown rice grain and white rice grain(p<0.05),and two kinds of exogenous selenium applied foliar spraying to reduce the content of Cd in grain is superior to soil nano-selenium application,and the effect of Cd content reduction by spraying 1mmol/L nanoselenium on leaf surface was the best.Under Cd-contaminated soil,the Cd concentration of white rice grain was reduced by 65.59%,respectively,compared to the control,when foliar spraying 1mmol/L nanoselenium on the leaves.By analyzing the form of Cd in soil,it was found that the application of selenium on the leaf surface had no significant effect on the form of cadmium in soil,but the use of Se in soil decreased the proportion of soluble Cd in the soil,and increased the proportion of the residual Cd.2.The hydroponic experiment was conducted to study Se and Cd interaction in seedling of rice,the results showed that the Vmax value increased,the Km value decreased.The nano-Se and sodium selenite promoted the absorption rate of Cd ions in 3h.At the same Cd concentration,the nano-Se and sodium selenite also promoted the absorption rate of the Cd ions in the root,but decreased the content of Cd in the upper part of the rice.The results of hydroponic test confirmed that the antagonistic effect of Se and Cd maybe not occur on the root surface,but on the transport of roots to the shoot of rice.