Effect Of Silicon And Selenium Fertilizer Leaf Surface Regulation On Reducing Cadmium And Lead Absorption In Rice

Reducing the heavy metal content in rice by applying silicon selenium is a scientific,efficient and operable method for farmland restoration.In order to explore the frequency,period of silicon selenium leaf regulation and the effect of joint application with soil on reducing the absorption of cadmium(Cd)and lead(Pb)in rice.In this study,two years of experimental research were carried out,and the leaf regulation of silicon selenium and soil fertilization of silicon selenium and combined application with leaf were set up in different periods.Its effects on rice yield of Cd and Pb cultivation,Cd and Pb content of rice,absorption transport of Cd and Pb,silicon,selenium,nitrogen,phosphorus,potassium and pH and effective content of soil were studied.The study results are as follows:(1)Leaf regulation of silicon selenium in different periods can increase rice yield.In the heading period and filling period of rice growth,the injection of silicon increases by 4.49%compared with CK,which is significantly higher than that of single injection in a growth period;the injection of selenium can increase by 3.21%～5.08% compared with CK.Both silicon selenium-based application and combined leaf application increased the rice yield by 3.94% to 14.56%,among which the most effective treatment was the combined application of the two.In general,selenium is more effective in increasing rice production than silicon production.(2)The regulation of the silicon selenium and the Cd and Pb content of brown rice.Among them,spraying silicon(33.64%)or selenium(34.67%)during the heading and filling periods of rice growth was significantly more effective on reducing Cd and Pb than a single spraying in a certain growth period.According to the National Standard for Food Safety(GB 2762-2022),the spraying of silicon or selenium twice or more times can make the Cd content of brown rice up to the standard,and the spraying once can make the Pb content of brown rice up to the standard.Cd and Pb content in brown rice decreased with increasing spraying times.Both silica and leaf application can reduce Cd and Pb content in brown rice.All treatments except the Cd and Pb contents below the limit specified in GB2762-2022.(3)The leaf regulation of silicon selenium and leaf application can reduce the enrichment ability of Cd and Pb in brown rice,and inhibit the transfer of Cd and Pb to brown rice by reducing the transport coefficient of Cd and Pb between straw-brown rice.Among them,selenium is better than silicon to inhibit the transport of Cd and Pb to shoots.(4)The content of silicon and selenium in brown rice can be significantly increased compared with the content of silicon or selenium fertilizer in different growth periods.The application of selenium fertilizer base and the combination application with leaf could improve the selenium content of all parts of rice,with the best effect on the selenium content of all parts of rice.(5)The effect of silica selenium leaf regulation on the effective state of soil pH and heavy metals was not significant.The combination of silicon selenium and the amount of Cd and Pb in the soil pH and reduced the reduction of Cd and Pb by 25.53% and 22.37%,respectively,with the best effect.According to the comprehensive analysis,the application of silicon and selenium to soil or leaf can effectively reduce the content of cadmium and lead in rice.Multiple application can reduce the content of cadmium and lead in brown rice below the national standard limit,and improve the content of silicon,selenium,nitrogen,phosphorus and potassium in brown rice,and have strong operability and generalization.