The Effects Of Different Types Of Selenium Fertilizer And Strengthening Measures On Growth And Soil Characteristics Of Adzuki Bean

Adzuki bean（Vigna angularis）,rich in nutrients,protein and starch,and lower in fat,rich in dietary fiber,calcium,iron and other mineral elements,and also contains polyphenols,phytic acid,saponins,pigments and other bioactive substances,was recognized with high medicinal value,and can supplement the nutrients needed by the body and prevent and treat diseases.It is also considered as a functional grain crop and is deeply loved by people.Selenium is an essential trace element for the human body.Selenium-rich agricultural products can convert inorganic selenium that is not easily absorbed by the human body in the environment into organic selenium,and easily absorbed by the human body and beneficial to human health in crops or animal agricultural products,so as to achieve the purpose of efficient and safe supplementation of selenium through daily food intake.At present,there are few reports on the selenium-enriched characteristics of adzuki bean.In this study,the effects of different concentrations of selenium fertilizer on the selenium content and yield of adzuki bean were studied by pot and field experiments,and the optimal selenium-enriched concentration of adzuki bean was determined.The effects of different application methods,soil moisture conditions and nitrogen application levels on selenium enrichment characteristics of adzuki bean were discussed in order to establish high-efficiency selenium-enriched cultivation techniques of adzuki bean.The main results are as follows:（1）Exogenous selenium fertilizer application was significantly increased the selenium content of adzuki bean grains.When different concentrations of sodium selenate and sodium selenite were sprayed on the leaves of adzuki bean,the selenium content in grains increased with the increase of selenium fertilizer concentration,and the selenium content exceeded 0.3mg/kg（higher than the selenium enrichment standard of legumes≥0.1 mg/kg）,while the utilization rate of selenium in grains increased first and then decreased.When the selenium concentration was 13.8 g/hm²,the selenium utilization rate of the grain was the highest,and the selenium content of the grain was 14.49%higher than that when the selenium concentration was 13.8 g/hm².In terms of fertilization methods,foliar application of selenium fertilizer significantly increased grain selenium content compared with root application of selenium fertilizer,and the proportion of grain selenium content was larger.When sodium selenite was applied under different soil water conditions,the soil relative water content of40%-50%had a tendency to promote the transfer of selenium to the grain,thereby increasing the selenium content of the grain.Nitrogen fertilizer promoted the transfer of selenium to grains.When the nitrogen application rate was 200 mg/kg,the proportion of selenium content in leaves sprayed with sodium selenite was the highest,and the selenium content in grains was 6 times higher than that of CK.（2）Exogenous selenium fertilizer application was promoted the yield and quality of adzuki bean.With the increaseing of selenium fertilizer concentration,the yield of adzuki bean increased first and then decreased.When sodium selenite was applied,the yield was the highest when the selenium concentration was 13.8 g/hm²,which was 24.17%higher than that of CK.When selenium fertilizer was applied under different selenium fertilizer types and nitrogen levels,the yield of adzuki bean was higher than that of selenium fertilizer when selenium fertilizer was sprayed on the leaves.After the application of nitrogen fertilizer,the yield increased with the increase of nitrogen application rate.When the nitrogen application rate was 200 mg/kg,the yield of foliar spraying sodium selenite was the highest,and the agronomic traits such as plant height,stem diameter,leaf length,leaf width and 100-grain weight were also significantly higher than CK.The content of soluble sugar in grains increased after the application of selenium fertilizer,and the content of soluble sugar in grains was significantly higher than that of CK when sodium selenite was applied.The application of sodium selenate and sodium selenite can significantly increase the grain fat content without nitrogen application,while the application of selenium-rich treasure and the application of sodium selenite after nitrogen fertilizer,the fat content increased but not significantly compared with CK.The starch content decreased after the application of selenium fertilizer,but did not reach a significant level.（3）Selenium fertilizer application was beneficial to the growth of adzuki bean.Selenium fertilizer application were increased the contents of chlorophyll a,chlorophyll b,total chlorophyll and carotenoid,increased the activities of catalase（CAT）,peroxidase（POD）and superoxide dismutase（SOD）in the leaves of adzuki bean,and reduced the content of malondialdehyde（MDA）.Among them,foliar application of selenium fertilizer were increased the activities of catalase（CAT）and superoxide dismutase（SOD）in adzuki bean leaves significantly.Foliar application of selenium fertilizer were increased the values of Fm,F0,Fv/Fm and Fv/F0 of adzuki bean leaves significantly,and the root application of selenium fertilizer had little effect on chlorophyll fluorescence parameters.The transpiration rate,net photosynthetic rate and intercellular CO₂ concentration of adzuki bean leaves were increased after the application of selenium fertilizer.When the nitrogen application rate was 200 mg/kg,foliar spraying of sodium selenite could significantly increase its rate.（4）Selenium fertilizer application has a positive effect on soil enzyme activity and microorganisms.The activities of soil urease,alkaline phosphatase and sucrase were partially increased after the application of selenium fertilizer,and the soil enzyme activity of root application of selenium fertilizer was stronger than that of foliar application of selenium fertilizer.When sodium selenate was applied to the root,the soil urease and alkaline phosphatase activities were the highest,which were 23.21%and 33.07%higher than CK,respectively.With the increase of soil water content,soil urease activity gradually increased while alkaline phosphatase and invertase activity decreased.The activity of soil urease and sucrase decreased when selenium fertilizer was applied after increasing nitrogen fertilizer.The soil urease activity of sodium selenite was significantly lower than that of CK at different nitrogen application rates.Selenium application was beneficial to the enrichment of beneficial rhizosphere microorganisms in the rhizosphere soil of adzuki bean.Sodium selenite had the greatest effect on improving the richness and diversity of soil bacterial communities.Comprehensive studies have shown that when the nitrogen application rate is 200 mg/kg,foliar spraying selenium concentration of 13.8 g/hm² sodium selenite has a better selenium strengthening effect,and the highest utilization rate of grain selenium and grain selenium content is higher than the selenium-rich bean standard.It can also promote the synthesis of chlorophyll and photosynthesis of adzuki bean,which is conducive to the growth and development of adzuki bean,so as to achieve the purpose of increasing yield and improving quality.