Effects Of Different Valence Selenium And Its Applications On Wheat Yield And Selenium Content In The Typical Selenium Deficient Area Of The Loess Plateau

Wheat is the staple food crop in Loess Plateau China, and its grain selenium(Se) deficiency directly affects the Se nutritional status of residents in this area. Since the rational Se content range is very narrow between lack and poisoning for the human, it is of great significance to improve reasonably the grain Se content to guarantee human health. A 2 year study was conducted in typical Se deficient agricultural area during 2012-2014 to investigate the effect of different valence selenium and its application methods on winter wheat yield, the Se content in different parts of wheat and Se utilization with improving the wheat grain Se content to 100 μg/kg. Further, the residual effects of residual Se in soil and wheat straw on the subsequent crops, soil total and available Se were measured. The objective of the experiment is to supply theoretical and practical knowledge for the effective regulation of grain Se nutritional quality of winter wheat by rational use of Se fertilizer in this and other similar region. Obtained results are as follows:1 Different valence Se and applications showed no significant effect on winter wheat yield, biomass, but significantly increased the Se content of wheat grain, stem and glume. Grain Se content was ranged from 109 to 397 μg/kg in the first year, and reached the target of 100 μg/kg by all treatments except for the control. Grain Se use efficiency ranged from 0.11% to 8.76% in 2013, the total Se use efficiency was 0.25–10.16%. The average total use efficiency of foliar applied Se was 7.79%, which was significantly higher than that of soil applied Se. At harvest, the soil total and available Se content was respectively increased by 98% and 23% in 0–20 cm and 20–40 cm soil by selenite–Se in 2013, but it showed no effect on 40–100 cm soil. Selenium in other form showed no significant effect on the total and available Se in 0–100 cm soil.2 The residual Se in soil and wheat straw showed no effect on the yield of winter wheat, but increased the Se content of grain, bran and flour, with the average Se content respectively being 271, 338 and 248 μg/kg and having reached the biofertication target. Selenium content of bran was averagely 145% higher than that in the flour when Se was applied by foliar application. In the second year, Se content of bran and flour was 114 and 116 μg/kg, and 101 and 116 μg/kg and still higher than the target, under the soil applied selenite-Se in the first year and then straw returned in the second year. During the grain processing, the preserving efficiency was 72–79% in flour in the first year and 81–88% in the second year. The Se biofortication index was respectively to be 3.6, 16.77, 0.3, 7.12(μg/kg)/(g/ha) for the soil and foliar applied selenite- or selenate-Se. Foliar application of selenite-Se in the second year, the flour Se biofortication index reached 0.69–0.79 μg/g regardless of whether straw is returned or not. Flour Se use efficiency ranged from 0.27‰ to 8.76‰ in 2013, and the total Se use efficiency was 0.93–29.13‰ over the two years, also different valence Se and its application methods showed significant effect on flour Se use efficiency.