Effect Of Exogenous Selenium On Photosynthetic,Yield Formation And Selenium Absorption In Foxtail Millet

With the development of functional agriculture and the improvement of National Diet structure,the development of selenium-rich products of coarse cereals has become a hot research topic.In order to study the effect of exogenous selenium on the growth and element accumulation of millet and provide scientific basis for planting selenium-rich millet,In this experiment,Zhangza 10,Jingu 21,Jingu 28 and Jingu 29 were used as materials to spray 3 concentrations of selenium fertilizer on the leaves at booting stage and filling stage respectively.To explore the the effects of spraying period and concentration of selenium fertilizer on photosynthetic,yield composition and element accumulation of millet,and determine the best period and concentration of selenium spraying on the millet leaves.The experiment was conducted in2018-2019 and the results are as follows:(1)Foliar selenium fertilizer could significantly improve chlorophyll content,photosynthetic fluorescence parameters,above-ground dry matter mass and total dry matter mass of millet,but had no effect on underground dry matter mass.Spraying 30 g/hm2 foliar selenium fertilizer is more conducive to the improvement of photosynthetic fluorescence parameters and dry matter quality of millet.Spraying 45g/hm2 foliar selenium fertilizer has an inhibitory effect.Spraying 30 g/hm2 foliar selenium fertilizer at booting stage could enhance photosynthesis and promote organic matter accumulation of millet,in which the above-ground dry matter and total dry matter could be increased by 14% ~ 27% and 13% ~ 25%respectively.(2)Spraying Selenium on the leaf could significantly improve the plant height,ear diameter,ear weight,yard number,ear grain weight,1000 grain weight and yield of millet,but has no effect on ear number and ear length.According to the analysis of membership function,the response of yield forming factors to different selenium concentration was prior to different spraying periods.The effect of selenium concentration on millet yield was as follows: 30 g/hm2 > 15 g/hm2 > 45 g/hm2,and the effect was better when spraying at booting stage.The results showed that spraying 30 g/hm2 foliar selenium fertilizer at booting stage was more beneficial to the yield formation of millet,the yield could be increased to 4500kg/hm2 ~ 5500 kg/hm2,with an increase of 7% ~ 9%.(3)Spraying selenium on the leaf had no effect on the Se content in the roots of millet,but significantly increased the Se content in the stems,leaves and grains,which was positively correlated with the selenium fertilizer concentration.Spraying selenium on the leaf could significantly reduce the contents of Hg,As and Cd in millet grain,which was negatively correlated with the concentration of selenium application.When spraying 45 g/hm2 foliar selenium fertilizer,the sequence of Se content in different parts of millet was: leaf > grain > stem > root.The Se content in grain of millet was the highest when 45 g/hm2 foliar selenium fertilizer was applied at booting stage,which could be increased to 0.23 mg/kg ~ 0.53mg/kg.The order of Se utilization rate of different varieties of millet was: Jingu 28 > Jingu 29 > Jingu 21 >Zhangza 10.The results showed that spraying 45 g/hm2 foliar selenium fertilizer at booting stage was beneficial to the accumulation of selenium in edible parts of millet,with an increase of 115% ~ 275%.Spraying 45 g/hm2 foliar selenium fertilizer at filling stage was more beneficial to reduce of Hg,As and Cd content in grains,with the reduction range of 49% ~ 67%,52% ~ 62% and 60% ~ 75%,respectively.