Effects Of Foliar Spraying Selenium Fertilizer On Physiological Characteristics And Quality Of Tartary Buckwheat

Selenium is an essential element for the human body and plays an important role in human health.China is a major selenium-deficient country.Too low selenium intake in the human body can cause many diseases.The research on selenium-enriched crops has attracted widespread attention from scholars at home and abroad.Tartary buckwheat is a food treasure with "dual use of medicine and food",and it is very popular.Its unique flavonoids include lowering blood pressure,lowering blood sugar,lowering blood lipids,preventing and treating cardiovascular diseases,promoting insulin secretion,and enhancing immunity.And so on,and tartary buckwheat itself contains selenium,but its content is not enough to meet the normal needs of the human body.In order to explore the effects of spraying selenium on the growth,physiological characteristics and quality of tartary buckwheat in different growth stages,and to provide a theoretical basis for the high-efficiency selenium-enriched cultivation of tartary buckwheat.In this study,"Weiheiqiao No.1" was used as the test material.Under the conditions of field production,spraying different concentrations of selenium(0mg/L,10mg/L,25mg/L,50mg/L)on the leaves during the early flowering,full blooming,filling,and mature periods.To study the effects of spraying different concentrations of selenium in different growth periods on the agronomic characteristics of tartary buckwheat,leaf photosynthetic pigments,osmotic adjustment substances,antioxidant system and flavonoids and selenium content in grains.The main findings are as follows:(1)Spraying selenium at different periods could increase the height of Tartary buckwheat and increase the number of main stem branches of Tartary buckwheat,but the change was not obvious.Under the Se25 treatment of early flowering,the plant height and branch number of Tartary buckwheat increased by 9.60%and 8.25% respectively.The yield per plant of tartary buckwheat reached the maximum under the treatment of Se25 in the filling stage,which was an increase of 202.20% compared with the control.(2)Spraying exogenous selenium in different growth periods had no obvious effect on chlorophyll a and carotenoids of tartary buckwheat leaves,but had a significant effect on chlorophyll b and total chlorophyll content.Chlorophyll a,chlorophyll b,and total chlorophyll content were the highest under Se10 treatment during the filling stage,which increased by 13.37%,19.94%,and 13.09% respectively compared with the control.However,selenium application inhibited the carotenoid content as a whole.Comprehensive analysis shows that spraying 10mg/L of selenium during the filling period is most beneficial to increase the photosynthetic pigment content of tartary buckwheat leaves.(3)Within the range of selenium concentration used in this study,in most cases,the SOD and POD content of tartary buckwheat leaves after spraying different concentrations of exogenous selenium in different growth periods were lower than the control.The SOD activity reached maximum under preflowering Se50 treatment,an increase of 3.03% over the control;The POD activity was the highest Se25 mature stage,20.17% more than the control;The content of MDA is the lowest Se10 treatment,which was23.36% lower than the control.Taken together,Spraying low concentration of selenium(≦25 mg/L)in the middle and late stage of Tartary buckwheat growth is more beneficial to delay the senescence of Tartary buckwheat leaves.(4)Different growth periods and different concentrations of exogenous selenium have different effects on osmotic adjustment substances in tartary buckwheat leaves.The content of proline was the highest Se25 treatment,33.2% higher than that of control,8.47% higher than that of control Se50 mature treatment and38.30% higher than that of control.Comprehensive analysis shows that spraying 25 mg/L of selenium during the reproductive and growth period of tartary buckwheat(filling period and maturity period)is most conducive to the accumulation of osmotic adjustment substances.(5)Spraying selenium in different growth stages can increase the total flavonoids and selenium content in tartary buckwheat grains,and increase with the increase of selenium concentration.The content reaches the maximum under the Se50 treatment at the mature stage.The content of total flavonoids increased by 16.49% compared with the control,and the selenium content of grains was 25 times that of the control group.The magnitude of the increment of total flavonoids content was at maturity period,filling period,pre-flowering period and full blooming period;the magnitude of the increment of selenium content was at mature period,full blooming period,filling period and pre-flowering period.In summary,when spraying exogenous selenium,the appropriate growth period and exogenous selenium concentration should be selected according to the research purpose.Spraying exogenous selenium with a concentration of 25 mg/L in the middle and late stages of tartary buckwheat growth can not only enhance its stress resistance,but also improve its yield and quality.