Effects Of Water Management And Spraying Leaf Retardant On Cadmium Uptake By Rice

With the development of industrial and mining enterprises and the discharge of "three wastes" and sewage irrigation in the production process,the overall situation of heavy metal pollution in the cultivated land nationwide is not optimistic,especially the problem of soil cadmium pollution.Cadmium(Cd),a heavy metal with strong biological toxicity,high chemical activity and refractory degradation,can be enriched in the human body through the food chain,and long-term accumulation can seriously damage human health.Rice has a strong ability to enrich soil Cd and transfer it to rice.Therefore,Cd has become the main inorganic pollutant that threatens food security production.In this paper,five different Cd-contaminated cultivated lands in Kunming and Chuxiong in Yunnan,Xinyu in Jiangxi,Nanping and Sanming in Fujian were selected to carry out field experiments on rice water management,and to explore different water management modes in the process of rice planting(flooding management during the whole growth period,flooding management during critical periods)and conventional water management)on soil Cd availability and rice Cd content;a field experiment of rice spraying foliar inhibitor and control agent was carried out in Cdcontaminated farmland in Kunming,Yunnan,and two kinds of rice,Honggu and Chujing 28,and four kinds of foliar surface were selected.The effects of different foliar inhibitors on Cd migration and accumulation in rice plants were investigated.To explore the regulation effects of water management and foliar inhibitor on Cd-contaminated soil,the test results can provide basic data for the safe use of Cd-contaminated farmland and the production of rice up to the standard,which has important practical significance.The main research conclusions are as follows:(1)Effects of different water management(flooding management in the whole growth period,flooding management in critical period and conventional water management)on soil p H and soil nutrients.The results showed that different water management had significant effects on soil p H,alkali-hydrolyzed nitrogen,available phosphorus,available potassium and organic matter content.In five field experiments,the p H value of the soil under flooding management during the whole growth period was increased by 3.42% to 10.67% compared with the soil p H value of conventional water management,and the p H value of the soil flooded during the critical period was higher than that of the soil under conventional water management.Compared with the increase of 0.68% to6.37%.As far as soil nutrients are concerned,water management measures will vary in the impact of soil available nutrients on the geographical location of the experimental sites and soil types.Among them,the content of alkaline-hydrolyzed nitrogen in the soil managed by flooding in the critical period of the Chuxiong test site in Yunnan decreased the most significantly,which was16.89%.The content of available phosphorus in the soil under flooding management during the whole growth period of Xinyu experimental site in Jiangxi increased most significantly,which was22.27%.The content of available potassium in the soil managed by flooding in the critical period of Xinyu experimental site in Jiangxi Province increased most significantly,which was 27.53%.The organic matter content in the soil under flood management during the critical period of the Sanming test site in Fujian increased most significantly,which was 14.64%.(2)The effects of different water management on the safe production of rice in Cdcontaminated farmland.The results show that both the flooding management during the whole growth period and the flooding management during the critical period can effectively reduce the soil available Cd content and rice Cd content.The performance rules of the two in different water management are as follows: flooding management in the whole growth period < flooding management in critical period < conventional water management.Through correlation analysis and regression analysis,a basic prediction equation was established,and the Cd content of rice under the water management model could be predicted through soil p H and soil Cd available content,and it was judged whether the rice Cd content could be reduced through water management in this area.The effect of different water management on rice yield.The results show that the rice yield of flooded management in the whole growth period decreases by more than 20%,and the promotion in field production should be minimized.Proper promotion.In conclusion,flooding management during critical period is the best water management mode to reduce Cd content in rice and maintain rice yield.(3)Four kinds of foliar inhibitor products were selected for rice field experiments,and the effects of different foliar inhibitors on reducing the transport of Cd from roots and straws to rice were discussed.The results showed that spraying the four foliar inhibitors could significantly increase the Cd content in rice plants(roots and stems),while reducing the Cd enrichment in rice leaves and rice.In the red valley rice experiment,the Cd content in the roots of the rice treated with GD increased the most,which was 6.13%,compared with the spray of clear water,and the Cd content of the stems of the rice treated with GD increased the most.,was 25.69%;the Cd content in the leaves of the rice sprayed with NGK had the most significant reduction effect,which was30.40%;the Cd content of the rice sprayed with the GWY treatment had the most significant reduction effect,which was 48.21%.In the rice experiment of Chujing 28,the Cd content in the stem of the rice sprayed with GWY increased the most,reaching 36.44%;the Cd content in the leaves of the rice sprayed with GD had the most significant reduction effect,which was 99.47%;The reduction effect of Cd content is the most significant,which is 61.69%.Spraying foliar inhibitor can inhibit the migration and accumulation of Cd in rice plants,and greatly reduce the enrichment of Cd in rice.Among them,the grain enrichment coefficient in the GWY treatment is the smallest,which is reduced by 48.21%.The foliar inhibitor can provide nutrients for the growth and development of rice while reducing the impact of Cd on rice,and increase rice yield.Among them,GWY treatment had the most significant increase in yield compared with CK treatment,which were21.86% and 41.66%,respectively.In conclusion,GWY foliar blocker is the best choice for reducing Cd enrichment in rice and increasing rice yield.