Study On Screening, Identification And Biocontrol Effects Of Antagonistic Bacterial Strains Against Soil-borne Disease

Plant soil-borne diseases is one of the most important plant diseases. They usually infect the roots of plants, causing root rot and even bring whole-plant vegetation to dead, cause major economic losses. In order to control the soil-borne plant diseases,two bacterial strains were isolated, the characteristic of occupancy in the soil, and the effect of biocontrol soil-borne plant diseases were also studed. The main results aer as follows:(1) Screening and identification of biocontrol bacteria in the soilFive high efficient chitinase producing strains were selected from the soil of Weihai and Nanjing.The antagonism experiment was taken place using five bacterial strains and the six soil-borne disease pathogens.Then two stains of biocontrol bacteria named sd07 and nl01 with high antagonistic effect had be gotten.The two strains of sd07 and nl01 are identified as Pseudomonas fluorescens and Pseudomonas kilonensis by traditional classification methods and sequencing of the application of 16s rRNA..(2) The characteristic of occupancy in the soilThe stains of sd07 and nl01 which are marked by Rifampicin can colonize in the soil for a long time. They can keep a high station after colonizing 50 days.The strain of sd07 and nl01 gets peak after colonizing 15 days.The strain of sd07 can live longer than the strain of nl01 in the sterilized soil and non-sterilized soil.(3) The effect of biocontrol soil-borne plant diseasesBiocontrol bacteria sd07 and nl01 have a certain inhibitory extent for damping-off of pine seedlings ,cotton fusarium wilt and cotton Verticillium wilt as well as having some growth-promoting role for cotton. The biocontrol effect of the strain sd07 is better than the nl01 compared these two strains.