Isolation And Identification Of Biocontrol Bacteria And Control Effect Study For Potato Common Scab In Inner Mongolia

The potato has a long history of cultivation,and it has been planted all over the world.It is the fourth most important crop in the world after wheat,rice and corn.It has been used in multiple industries for its strong resistance,short growth cycle,wide adaptability and high nutritional value.With the implementation of the country staple grain strategy,the demand for the potato industry has gradually increased.Potato industry is rapidly developing.Potato common scab is a soil-borne disease caused by actinomycetes belonging to the Streptomyces genus,which brings serious economic losses to all countries in the world.It is showing a trend of increasing year by year.At present,there are no very effective measures to prevent and control this disease.China is a big country in the potato industry,and the incidence of common scab in the main planting areas is also very serious.Many methods are used to prevent and control the production,but the effect is not very satisfactory.All traditional methods have certain drawbacks in some aspects.In contrast,the use of microbial strains for biological control is a better approach.In this study,Bacillus spp.was isolated from twenty-six soil samples from ten regions of Inner Mongolia.Antagonistic bacterias were screened through two steps.Pot experiments were conducted to further verify the biocontrol effect of antagonistic bacterias,and antagonistic bacterias were systematically identification by morphology,physiology,biochemistry and molecular.The main results are as follows:(1)201 strains of Bacillus spp.were isolated from some soil samples by diluting the coating with a water bath at 80?.(2)Using the paper dish method for the first screening,92 strains of antagonistic bacteria were screened;the Oxford cup method was used for the second screening to determine the inhibitory effect of the antagonistic bacterias on the pathogenic bacteria.Comprehensive the first screening and the second screening results selected No.3 and No.14 antagonistic bacterias for the further testing.(3)The two antagonistic bacterias were potted in spring.The results show that the twoantagonistic bacterias can significantly reduce the incidence,pathogenesis grade,desease index of potato common scab.The biocontrol efficiency respectively reached 69.89% and70.57%.(4)The two antagonistic bacterias were also potted in autumn.The autumn pot test increased the application of single antagonistic bacteria in a single application.The experimental data showed that single and double application of antagonistic fermentation broth can significantly reduce the incidence,pathogenesis grade and disease index of potato common scab.The biocontrol efficiency of single application of antagonistic bacteria No.3and double application of antagonistic bacteria No.3 was 60.88% and 72.96%,respectively.The biocontrol efficiency of the single application of antagonistic bacteria No.14 and the double application of antagonistic bacteria No.14 was 59.88% and 76.40%,respectively.(5)The results of two pot experiments showed that antagonistic bacteria No.3 and No.14 have good biocontrol effects of potato common scab,can significantly reduce the incidence and disease index.(6)The antagonistic bacterias No.3 and No.14 were systematically identified by morphology,physiology,biochemistry and molecular biology.The comprehensive results showed that antagonistic bacteria No.3 was Bacillus siamensis,and antagonistic bacteria No.14 was Bacillus velezensis.