The Improvement Of Selenium Nutrition Status Of Residents In Low-selenium Areas Of Weibei Dryland By Agronomic Selenium Biofortified Wheat

Selenium（Se）is an essential nutrient for the human body.Low dietary Se can cause a series of health problems.Endemic Kaschin-Beck disease is found to be related to low Se in the environment.The Weibei area is located in China’s low soil Se belt.In the 1970s,it has the highest prevalence of Kaschin-Beck in China.For soil Se in the region is extremely low,crops are generally low in Se concentration.Present study carried out an questionnaire survey with randomized stratified clustered sampling method.Two counties with most serious prevalence of Kaschin-Beck disease were selected,Yongshou county and Linyou County.Yangling district,non-disease area in Guanzhong region of Shaanxi province was chosen as control.Two hundred and seventy permanent residents from three natural villages of each counties were randomly chosen for investigation of detail information of daily intake food.And a field experiment was carried out in Yongshou to study the effects of Se fertilizer form and application mode on wheat grain yield,Se content in various parts,and also the residual effect was also determined.With the results,the cost of applying agronomic Se fortified wheat to improve resident’s daily Se intake was evaluated with the cost-benefit method analysis with the purpose of providing scientific basis for increasing Se nutrient intake in low-Se areas through agronomic biofortification method.The results were as follows:1.Compared with the residents in Yangling District,the residents of Yongshou County and Linyou County have less diverse dietary sources,whose daily food are still dominated by crop grains.The daily Se intake of Yangling residents is 61.8·d-1,which is significantly higher than that of residents in Yongshou County and Linyou County,25.0 and 35.0μg·d^-1,respectively.Although the dietary Se intake of the two counties are higher than the minimum dietary requirement for human Se nutrition 22μg·d^-1,the intake is still far below the recommended requirement of human Se 50μg·d^-1.The difference is closely related to the low Se crop,dietary structure and economic income of the residents.2.Se fertilization in Weibei dryland can significantly increase the Se content of wheat grain and reach the target Se content of 100μg·kg^-1 with no significant effect on wheat.grain yield.Se fertilizers and Se application methods have different effects on Se content in wheat organs.The response of wheat to sodium selenate was more sensitive than sodium selenite.The Se biofortified index of wheat grains with soil applied and foliar sprayed selenate are 5,16(μg·kg^-1)/(g·ha^-1)and the Se biofortified index of wheat grain are 0.27,8(μg·kg^-1)/(g·ha^-1)with selenate soil application and forliar spray,respectively.Different Se fertilizers and Se application methods have different residual effects.After applying sodium selenite,the total soil Se and available Se content in 0-60 cm soil layer are significantly increased.Selenite has more durable residual effect than selenate.Foliar application of selenate has one more year’s residual effect and soil application of selenite has two more years’residual effect.3.Labor productivity loss per capita is$30.78,and the cost of Se nutrient supplements is$35.0-37.84,while the cost of fortified Se wheat is$1.11.The cost of Se biofortified wheat is 32-34 times less than cost of Se supplement.The cost-benefit ratio of the Se fortified wheat is 1:27.7,which has better economic benefits.