| Microorganisms widely exist in the natural environment,and their activities affect the transformation of soil materials and plant growth,and play an important role in the sustainable development of agriculture.Tobacco is an important pillar industry in China's economic development.In order to avoid the destruction and utilization of traditional soil and pollute the environment by chemical fertilizer,it is very important to develop "white agriculture" with microbial agriculture as the core.In this experiment,the endophytic and rhizosphere bacteria of tobacco in Yanbian area were identified by 16SrDNA,and the microbial diversity between varieties and regions was studied.The growth promoting strains with the ability of producing IAA were screened by Salkowski colorimetric method,and the liquid medium was optimized to study the effect of interaction between bacteria on the germination and growth of tobacco seeds,so as to master the development of the available growth promoting bacteria and compound bacterial fertilizer in Yanbian area.To improve the soil environment and cultivate better quality tobacco to lay the foundation.The main conclusions of the study are as follows:1.A total of 29 genera and 72 species of endophytic and rhizospheric bacteria were isolated from Wangqing,Helong and Yanji areas.Among them,Corynebacterium.,Acineiobacier,Serratia,Rothiaaeria,Flavobacterium,Enterobacterare found only in Wangqing area.Sporosarcina,Paenarthrobacterand Brevundimonas are found only in the Helong area.And Cellulosimicrobiuma,Sphingopyxis,Paenibacillus,Shinellafusca,Kocuria and Enterobacter are found only in YanJi area.Bacillus and Pseudomonas were found in tobacco and rhizosphere soil in these areas,so they were dominant bacteria and spores.The number of Bacillus is the largest,and it is the most dominant genus.2.Among the bacteria isolated from the endophytic and rhizosphere soil of tobacco in Yanbian area,28 strains had the ability to produce IAA,accounting for 38.89%of the total bacteria.And Bacillus was the dominant genus.The unit yield of strains m10,m53 and m60,IAA was divided into 24.73mg L-1,26.8mg·L-1,22.11mg·L-1.3.The IAA yields of strains m10,m53 and m60 reached the maximum value at 72h,24h and 48h.There was a significant difference in the content of IAA produced by the strain with tryptophan added compared with the contrast.The optimum pH of strains ml0,m53 and m60 were 8,6 and 6.The optimum carbon source for all there strains was starch,and the optimum concentrations were 10g·L-1,20g·L-1 and 10g·L-1.The optimum nitrogen source is peptone and yeast powder,and the concentrations are 15g·L-1,20g·L-1 and 20g·L-1.The concentration of magnesium sulfate is lOg·L-1,15g·L-1 and 10g·L-1.4.Response surface method was used to optimize the liquid fermentation medium of strain ml0,m53,m60.The optimum medium conditions for IAA production were as follows:carbon source concentration 19.95g·L-1,nitrogen source concentration 20.97g·L-1,MgS04 concentration 15.37g·L-1,pH value 6.16,The content of IAA produced by strain M53 was 47.16 mg·L-1.The optimum conditions are verified,and there was no significant difference between the actual and theoretical results.5.Compared with the control group without growth-promoting bacteria,The germination power,germination percentage,germination index and vigor index increased by 30.61%,8.36%,31.13%and 36.9%,respectively,and the seedling length and root length increased by 11.37%and 57.11%,respectively.The mixed application of strain m53 and m60 had the most significant effect on tobacco seeds and seedlings under T6 treatment. |
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