Effects Of Selenium Fertilizer On Yield And Quality Of Vegetable Sweet Potato

Selenium is one of the essential trace elements for human body,selenium deficiency can easily induce a variety of diseases,can increase selenium intake through the consumption of selenium-rich vegetables to achieve the purpose of selenium supplementation.The combination of vegetable sweet potato,which are rich in nutrients and have health benefits,and the combination of the two greatly enhances the nutritional value of vegetable sweet potatoes.In this study,‘Guangcaishu 5’was used as the experimental material,used sodium selenite as the selenium source,and set 8 soil selenium application gradients of 0（CK）,1.0,1.5,2.0,2.5,3.0,3.5,4.0mg·kg^-1to study the effects of different selenium application concentrations on the plant growth,yield,nutritional quality,selenium accumulation and soil nutrients of vegetable sweet potato,and screened out the best selenium application concentration for vegetable sweet potato,and provided theoretical basis for the selenium-enriched cultivation of vegetable sweet potato.The main results are as follows:1、Appropriate amount of selenium can promote the growth and development of vegetable sweet potato and improve the yield.The plant height,stem diameter,number of branches per plant,leaf area and yield of vegetable sweet potatoes increased significantly after selenium application,and all of them showed a general trend of increasing and then decreasing with the increase of selenium application concentration,with the best effect at 2.0～2.5 mg·kg^-1selenium application treatment,in which the yield was significantly higher at 2.0 mg·kg^-1selenium application treatment than other treatments,and increased 37.26%compared with CK.Selenium application significantly increased the chlorophyll content of vegetable sweet potato by 10.34%～20.69%compared to CK,with the most significant increase under1.5～2.0 mg·kg^-1treatment2、Appropriate amount of selenium can improve the quality of vegetable sweet potato.The soluble protein,Vc,water content,soluble sugar,sucrose,anthocyanin,polyphenol and flavonoid content of the plant increased and nitrite and crude fiber content decreased after selenium application.The quality improvement showed concentration responsive changes with selenium application,the soluble protein content was highest at 2.0 mg·kg^-1;the Vc content was highest at 3.0 mg·kg^-1;the water content was highest at 1.5 mg·kg^-1;the contents of soluble sugar,anthocyanin and flavonoid were highest at 2.5 mg·kg^-1;the sucrose content was highest at2.0～3.0 mg·kg^-1;and the polyphenol content was the highest at 2.0～2.5 mg·kg^-1;the content nitrite was significantly lower than CK in the range of selenium application concentration≤2.0 mg·kg^-1,treatment with selenium application concentration≥1.5 mg·kg^-1could better reduce crude fiber content.3、Selenium application affected the uptake and accumulation of mineral nutrients in vegetable sweet potato,which varied according to the concentration and organs of selenium application.After appropriate amount of selenium,the contents of N,K and Mn in vegetable sweet potato decreased significantly,the contents of Ca,Mg and Fe in vegetable sweet potato increased significantly,and the contents of Cu,Zn and P in vegetable sweet potato varied according to organs.Overall,Ca and Mg contents were higher in the high concentration(≥3.0 mg·kg^-1)selenium application treatment and Mn content was higher in the 3.0 mg·kg^-1treatment,while N and Fe contents were higher in the low concentration(≤1.5 mg·kg^-1)treatment and P,K,Cu and Zn contents were higher in the 1.0 mg·kg^-1treatment.4、Selenium application treatment can increase the selenium content of soil and plant.Soil selenium content increased with the increase of selenium application concentration,and soil selenium content increased 37.93%～237.93%compared with CK,and showed a highly significant linear positive correlation with soil selenium application concentration.The selenium content of each organ of vegetable sweet potato showed an increasing trend with the increase of selenium application concentration,and within the set range of soil selenium application,the selenium content of leaves,stalks and stems reached the highest 15.32 mg·kg^-1,9.31 mg·kg^-1,and 11.32 mg·kg^-1,respectively,and the selenium content and selenium accumulation in each organs showed that leaves>stalks>stems,and the leaves were the easiest to accumulate selenium.5、Appropriate amount of selenium can improve soil p H,organic matter content and soil available nutrient contents.Soil p H and soil alkali-hydrolyzable nitrogen content were not significantly correlated,soil selenium,available phosphorus and organic matter content were highly significantly positively correlation with selenium concentration,and available potassium content was highly significantly negatively correlated with selenium application concentration.Compared with CK,selenium treatment significantly increased soil p H and organic matter content,the effect of different selenium concentration on soil p H was not obvious;and the effect of higher selenium concentration(≥2.0 mg·kg^-1)on soil organic matter content was better than that of lower concentration treatment.Appropriate amount of selenium can improve soil alkali-hydrolyzable nitrogen,available phosphorus and available potassium contents,but high concentration of selenium treatment can reduce soil available nutrient contents,the soil organic matter content and soil available nutrient contentswere higher when the selenium application concentration was 2.0 mg·kg^-1.In conclusion,the optimum selenium application concentration for improving soil fertility,promoting the growth of vegetable sweet potato,improveing quality and increasing yield is 2.0 mg·kg^-1.