The Characteristics Of Se In Se-Enriched Soils In Main Tobacco-Groeing Areas Of Guangxi And Study On Chemical Methods To Activate Se In Siols

Selenium?Se?is an essential trace element of human beings,which as the active center of selenoenzymes and selenoproteins and plays an key role in biological functions in organisms.Therefore,the importance of selenium to human health has get more attention.A large area of selenium-rich soil was observed in Guangxi,where the availability of Se in soil was relatively low,consequently affecting agronomic biofortification of crops with Se.Thus,the current study aims to investigate?1?the influencing factors of the selenium availability in soil;?2?the feasibility of applying organic and inorganic materials as activators increasing Se availability in soil.The findings can be help for effectively utilizing Se-rich soil resources in Guangxi and promoting the production of natural Se-rich agricultural products.For this purpose,four soil activators,F,M,Z and G were selected to this study.The effects of different activators on the availability of selenium in soil and the uptake and accumulation of selenium by tobacco plants were studied by combining culture experiment with pot experiment and field experiment,that is on the basis of investigating the selenium characteristics of selenium-rich soils in tobacco-growing areas.The main research results were as follows:?1?The results of selenium investigation in the soils of the main tobacco growing areas in Guangxi showed that:The significant differences in the Se distribution in differentmain tobacco growing areas of Guangxi.We categorized abundance and deficiency thresholds based on the total Se concentration in soil.More than 98%of the soil selenium content in Hezhou tobacco-growing area has reached"sufficient"Selenium and"rich"selenium levels,while more than 85%of soil selenium content in Hezhou tobacco-growing area reached"sufficient"and"rich"selenium levels.In the tobacco growing areas of Hezhou,the contents of soil selenium in Fuchuan,Zhongshan and Zhaoping tobacco-growing area were 0.199mg/kg?0.802 mg/kg,0.179 mg/kg?0.678 mg/kg and 0.134 mg/kg?0.656 mg/kg,respectively.The average value of soil selenium content in tobacco growing area was:Fuchuan tobacco area?0.428 mg/kg?>Zhongshan tobacco area?0.318 mg/kg?>Zhaoping tobacco growing area?0.292 mg/kg?;In the tobacco growing areas of Hechi,the contents of soil selenium in Luocheng,Nandan and Tian,e tobacco-growing area were 0.08mg/kg?0.96mg/k,0.12mg/kg?0.97 mg/kgand 0.12?0.56 mg/kg,respectively.Relevant analysis results showed that there was a significant positive correlation between soil organic matter and soil alkali-hydrolyzed nitrogen content and soil total selenium content.Moreover,there was a significant positive correlation between soil p H value and Available selenium content.?2?The results of simulated soil culture experiment showed that the available selenium content and p H value of soil treated with four soil activators inculding F?TS2?,M?TS3?,G?TS4?and Z?TS5?were higher than control treatment,and the p H value of TS4 and TS3treatment was more higher,and the available selenium content of soil treated with TS2 and TS3 was the highest.Adding soil activators changed the forms of selenium in soil.The contents of Se⁴⁺water-soluble selenium,Se⁶⁺water-soluble selenium,exchangeable selenium and carbonate-bound selenium in soil treated with F?TS2?,M?TS3?,Z?TS4?and M?TS5?were higher than control treatment,while the contents of organic-bound selenium were lower than control treatment.?3?The results of soil pot experiment showed that the dry weight of tobacco plants treated with four kinds of soil activator and different activator all were higher than control treatment at 75 days after transplantation,and the effect of TS4 and TS5 treatment were more effective.Selenium content in organs of tobacco plants treated with four soil activators TS2,TS3,TS4 and TS5 increased 30 days or 75 days after transplantation.The soil p H value of TS5 and TS2 treatment was significantly higher than control treatment at 30 days after transplantation.The soil available Selenium content of TS3 and TS4 treatment was significantly higher than control treatment at 75 days after transplantation,which may be related to soil available Selenium at later stage.75 days after transplantation,the proportion of Se accumulation in stems and leaves of tobacco plants treated with four kinds of soil with different activators higher than control treatment.The increase of 6-valent water-soluble selenium,4-valent exchangeable selenium and the decrease of organic bound selenium in soil were positively correlated with selenium-rich selenium content in tobacco leaves.Adding different activators increased the soil p H value and the contents of soil organic matter,available sulfur,available phosphorus,available potassium and other effective nutrients,and promoted plant uptake of P,K,S and other elements.?4?The field test results show that:t,different dosage of activator increased the soil p H value and organic matter content,and promoted the absorption of nitrogen,phosphorus and potassium by tobacco plants.The agronomic traits and biomass of tobacco plants treated with Z80?80 kg/mu?were better than those treated with control.Z40?40 kg/mu?and Z80?80kg/mu?,two treatments could effectively increase selenium content in tobacco leaves.