Control Effect Of Biochar On Tobacco Bacterial Wilt And Regulation Of Soil Microecology

Biochar is a soil improver that can improve soil physical and chemical properties and promote plant growth.It has characteristics such as large specific surface area,well-developed pore structure,strong stability,good adsorption performance,and has great application prospects in soil microecological improvement,prevention and control of soil-borne diseases.In this paper,biochar is used as the research material,and tobacco bacterial wilt is used as the research object.In combination with laboratory experiments,potted plans,and field tests,the physical and chemical properties of biochar,the dynamics of growth and decline in the soil environment,the effects on the growth of tobacco,the physical and chemical properties of the soil,and the diversity of soil microbial communities were studied to explore the effects and mechanisms of biochar on rhizosphere soil microecological improvement and tobacco bacterial wilt prevention.The main findings are as follows:（1）Characterization results of biochar show that biochar is alkaline,and has a larger specific surface area and a developed pore structure.The difference between the two types of biochar is that the pH,N,P,K,ash content and pore size of pine biochar are lower than those of straw biochar,and specific surface area,pore volume,C,H,S content are higher than those of straw biochar.It shows that the source of biochar is an important factor affecting the physical and chemical properties.（2）Biochar has an inhibitory effect on Ralstonia solanacearum.The application of more than1.5%biochar in soil can significantly inhibit the growth of R.solanacearum,and this inhibition effect is concentration-dependent and persistent;1.5%,3%,and 5%doses of biochar have significant adsorption ability of R.solanacearum;more than 0.5%dose of biochar can significantly inhibit the movement of R.solanacearum.Indicating that biochar can reduce the density and pathogenicity of bacterial wilt in soil,and has the potential to prevent and control tobacco bacterial wilt.（3）Biochar can increase the yield and quality of tobacco,and has significant control effects on tobacco bacterial wilt.The pot experiment showed that the best effect was achieved by adding 5%biochar,and the control effect of bacterial wilt reached 81.38%.Biochar above 1.5%can significantly reduce the number of bacterial wilt in tobacco rhizosphere and non-rhizosphere soil.Field tests showed that biochar could promote tobacco growth,the yield value of tobacco leaves and the proportion of upper and middle tobaccos,coordinate chemical components,and improve the internal quality of tobacco leaves.The effect of 15000 kg·hm^-22 was most obvious.The results of the disease investigation found that 60 and 90 days after transplantation,the application of 15000 kg·hm^-22 biochar had the lowest incidence and disease index,and had the best control effect on bacterial wilt.（4）Biochar can improve soil physical and chemical properties.Biochar increased the pH,available phosphorus,and available potassium content of soil in pot,and reduced the content of soil nitrate and ammonium nitrogen,which was significant in treatment PBC3 and PBC5.Environmental factors and bacterial wilt have extremely significant or significant correlations.Among them,nitrate nitrogen and ammonium nitrogen content are positively correlated with disease index and incidence,and pH,organic matter,available phosphorus and available potassium content are negatively correlated.In the field test,the use of biochar increased soil pH and nutrient content,and the enhancement effect increased with the increase of the amount of biochar.Among them,the application of 15000 kg·hm^-2biochar treatment and the application of 22500 kg·hm^-22 were better.Statistical analysis of the data found that p H is a highly negatively correlated factor with the disease index and incidence of bacterial wilt,indicating that the main reason of biochar preventing tobacco bacterial is the improvement of soil physical and chemical properties and adjusting the pH.（5）Biochar can improve soil microecology.The results of diversity index analysis and PCoA analysis showed that biochar increased the alpha and beta diversity of microbial communities in rhizosphere soil,with the most significant difference being 5%;Species composition analysis showed that biochar treatment increased the relative abundance of Streptomyces related to disease effects;RDA analysis showed that biochar had an improved effect on soil physical and chemical properties,and there was a certain correlation between bacterial groups and soil physical and chemical properties.