Study On The Control Effect Of Seedling Substrate Mixing Bacteria On Tobacco Growth And Bacterial Wilt

Tobacco bacterial wilt caused by Ralstonia solanacearum is a devastating disease on tobacco,and has the characteristics of wide harm and refractory prevention.At present,green and sustainable biological control technology is tobacco hotspots of bacterial wilt control.Studies have shown that building a strong biological barrier at the plant seedling stage can significantly reduce the occurrence of plant diseases in the future.Butthe following problems still exist in the application of biological control in agriculture:the lack of good strains for different targets,the poor adaptability of single biocontrol bacteria to the environment,the instability of biocontrol effect and the optimal application method of biocontrol agent.therefore,finding an excellent strain or combination of strains with good control effect against tobacco bacterial wilt and its optimal application method are of great significance for controlling bacterial wilt.In this paper,by evaluatingthe optimal initial inoculation amount of the substrate mixed bacteria and the in hibitory effect of four kinds of rhizosphere promoting bacteria on Ralstonia solanacearum,the optimal initial inoculation volume of 10~7 cfu/g and the strains that inhibited the bacterial colony proliferation of cyanobacteria were screened.Then,under green house and field conditions,the seedling-growing substrate mixing method was used to evaluate the control effects of four biocontrol bacteria on tobacco growth and bacterial wilt,and the single biobacteria-resistant strain with the best effect on tobacco growth and bacterial wilt control was identified.On this basis,the effect of the method of mixing biological control bacteria in the substrate on tobacco growth and bacterial wilt control was further evaluated,and the biological control bacterial combination that promoted tobacco growth and had the best control effect on bacterial wilt was selected,and Finally,a technical system for preventing and controlling tobacco bacterial wilt caused by mixing bacteria in seedling substrates is formed.the main findings are as follows:1 It is clarified that the optimal initial inoculum of mixed bacteria for seedling substrate is 10~7 cfu/gUsing Bacillus subtilis(04179)and Paenibacillus polymyxa(03434)as the test strains,the method of mixed culture of seedling substrate was used to evaluate the growth of bacterial seedlings and bacterial wilt control effect by different initial inoculation amount of mixed germicide of the seedling substrate in the green house through pot experiment,the different initial inoculation amount of mixed germicide in the seedling substrate has no significant effect on the control effect of tobacco bacterial wilt.the initial inoculation amount of mixed germicide in the seedling substrate is10~7cfu/g can significantly promote tobacco seedling growth.To sum up:the optimal initial inoculation amount of the substrate-mixed bacteria inthe seedling substrate is 10~7cfu/g.2.Clarified the bacteriostatic effect of 4 rhizobacteriaThrough the plate confrontation test,it was found that Bacillus subtilis,Bacillus amyloliquefaciens(pre-laboratory preservation)and Paenibacillus polymyxa can significantly in hibit the growth of Ralstonia solanacearum.Pseudomonas fluorescens(10040)has no in hibitory effect on the growth of Ralstonia solanacearum.3 Usingthe method of mixing bacteria in the seedling substrate,the effects of 4rhizosphere growth-promoting bacteria and 2 biocontrol combinations on the growth and development of tobacco seedlings are clarifiedunder green house conditions,the seedling-growing substrate mixing method was used to evaluatethe effects of four rhizosphere growth-promoting bacteria and two biocontrol combinations on the growth and development of tobacco seedlings.(the initial inoculation amount of biobacteria-resistant combination was 10~7 cfu/g,and the ratio was 1:1)the results showed that the mixed growth of Bacillus subtilis in the seedling substrate had the best effect on tobacco growth,followed by the biocontrol bacteria Bacillus subtilis+Paenibacillus polymyxa(Pp+Bs).4 Evaluated the control effect of single and combined bacterial agents on tobacco bacterial wilt in seedling stage and field stageIn green house and field conditions,the method of mixing substrates with seedlings was used to determine the effect of single and combined bacterial agents on the occurrence of bacterial wilt.the results showed that the combined bacterial agents were significantly more effective in controlling tobacco bacterial wilt than single bacterial agents.under green house conditions,the single fungus with Bacillus subtilis hasthe best disease prevention effect,andthe combined fungus with Bacillus subtilis+Paenibacillus polymyxa(Bs+Pp)combination has the best control effect on tobacco bacterial wilt good,the final control effect is 31.94%;under field conditions,the single fungus is the best with Paenibacillus polymyxa,the final combination of Bacillus subtilis+Paenibacillus polymyxa(Bs+Pp)fungus on tobacco bacterial wilt the prevention effect is 51.40%.5 Integrated seedling substrate mixing technology,the field demonstration application effect is obviouscombined measures such as seedling-growing substrate mixing technology and streng Thening field management were used to systematically evaluatethe control effect of the microbial inoculumin the seedling-growing substrate on tobacco growth and bacterial wilt.the results showed that the seedling-growing substrate mixing technology could promote the early growth and rapid growth of tobacco,and reduce with the occurrence of tobacco bacterial wilt,The relative control effect was 41.33%in the peak period compared with the non-demonstration area.the output value of tobacco increased by 6424.95 yuan/ha,and achieved good application and demonstration effects.