Effects Of Selenium-Containing Organic Fertilizer On Selenium Accumulation In Highland Barley In Tibetan Area

Selenium is an essential micronutrient for the human body.Lack of selenium will cause Keshan disease and Kashin-beck disease,which will adversely affect the health of residents.Most areas in Tibet are selenium deficient.Therefore,kashin-beck disease（KBD）,an endemic disease caused by insufficient selenium intake,has a long history of prevalence,a wide range of disease areas and a serious disease in Tibet,ranking the first in China.It is urgent for residents to supplement selenium.Dietary selenium supplementation through biofortification is a relatively simple,safe and easy to popularize method compared with other methods.As the main self-produced staple crop in Tibet,how to improve the selenium content in highland barley through biological enrichment is of great significance for the residents of Tibet to supplement selenium.On the other hand,the deviation of farmland fertility and the low content of soil organic matter restrict the sustainable production of local agriculture.The application of organic fertilizer can improve soil texture and improve soil fertility.Based on this,this study applied selenium-rich organic fertilizer to promote the Tibetan highland barley grain selenium content and soil fertility as the goal,through cultivating experiment,pot experiment and field experiment combined with the research methods,explore the selenium-rich organic part instead of chemical fertilizer under the conditions of highland barley selenium absorption transport characteristics and grain selenium accumulation and impact on soil fertility have been the main results are as follows:（1）Effects of selenium-rich organic fertilizer application on soil fertility and selenium availability.Compared with no fertilization,the addition of organic fertilizer can significantly increase the content of organic matter,available nitrogen and available phosphorus in soils,and improve the level of soil nutrients.However,the content of available selenium and water-soluble selenium in selenium-rich organic fertilizer decreased during the cultivation period,and the content of available selenium and water-soluble selenium decreased by 26.27%and 40%,respectively.The ratio of available selenium to water-soluble selenium was relatively stable during the cultivation period.（2）Effects of exogenous Selenium supplementation on wheat seedling growth and selenium absorption,accumulation and transport.Soil selenium concentration of 5.35mg·kg^-1 could inhibit the growth of wheat,and the inhibition degree was strengthened with the increase of soil selenium concentration.Plant height of 23.85 mg·kg^-1decreased by 60.78%compared with the control.The enrichment ability of wheat organs to soil selenium was leaf>stem>root,and the bioenrichment coefficient（BCF）of each part of the plant decreased with the increase of selenium application.The transfer coefficient between different parts（TF）showed as TF aboveground part/underground part>TF leaf/root>TF stem/root.（3）Field experiments were conducted to explore the effects of different fertilization methods on soil fertility.The soil organic matter content decreased from the heading stage to the maturity stage regardless of fertilizer application alone or organic fertilizer replacement.Organic fertilizer replacement increased soil organic matter content at the heading stage and maturity stage,and organic matter content increased with the increase of organic fertilizer replacement ratio.When the replacement ratio of organic fertilizer was 60%,soil organic matter content increased by 3.09 g·kg^-1（28.53%）at the heading stage and 2.02 g·kg^-1（18.59%）at the maturity stage compared with the control.Field experiments were conducted to explore the effects of selenium-rich organic fertilizer application on barley growth,selenium absorption,transport and accumulation.From the heading stage to the maturity stage,the growth of barley plant height under organic fertilizer replacement was higher than that under chemical fertilizer alone,and the effect of organic fertilizer replacement was longer than that under chemical fertilizer alone.Exogenous selenium supplementation had significant effects on increasing grain thousand-grain weight and grain selenium content.The 1000-grain weight increased by 10.04 g compared with the control after applying exogenous selenium,but the effect of organic fertilizer replacement on 1000-grain weight was not significant.Organic fertilizer replacement reduced the plant BCF,and under different selenium application levels at the heading stage,the plant BCF showed high selenium application>medium selenium application>low selenium application.During the plant growth,the BCF of each treatment at the maturity stage decreased compared with the heading stage.The selenium transfer coefficient of the plant was as follows:TF leaf/stem>TF aboveground/underground part>TF leaf/root>TF stem/root.The transport coefficient of organs to grains decreased with the increase of the organic fertilizer replacement ratio.In conclusion,organic fertilizer replacement can improve soil physical and chemical properties,increase soil organic matter content and improve soil fertility.The application of selenium-rich organic fertilizer can improve the selenium content in highland barley grain under the premise of soil improvement,and achieve the goal of food production in Tibetan areas,guaranteeing the selenium intake of residents and improving the soil environmental quality by increasing the application of selenium-rich organic fertilizer.