Screening And Comprehensive Prevention Of An Antagonistic Bacterium Strain Of Sclerotinia Sclerotiorum Of Sunflower

Sunflower rot disease is a worldwide disease caused by Sclerotinia sclerotiorum (Sclerotinia sclerotiorum (Lib.) de Bary), hosts a wide range plant and causes serious harm. In this study,30rhizosphere soil samples from the region of Inner Mongolia, like Hohhot, Baotou City, Wulanchabu Bayannur League, Chifeng City, Tongliao City, Hebei Province, and other area cities and counties with plant tissues, sclerotinia sclerotiorum biocontrol strains isolated from the sample and its control effect were designed to study the theoretical basis and research basis for the biological control of Sclerotinia. Experimental results show that:30rhizosphere soil samples collected from various regions, after separation screening over1300strains of the bacterial strains, better antagonistic effect of a total of25bacterial strains of bacteria, accounting for1.916%. The strain of CF4-51antibacterial activity is the best and the inhibition zone up to3.2cm. Inhibitory activity of CF4-51strain in vitro leaves is85.33%, pot and field control effect are78.36%and64.58%respectively.The bacterial morphological observation and physiological and biochemical characteristics, combined with16S rDNA sequence analysis, the strain of CF4-51was identified as Bacillus cereus (B. cereus.). Strain of CF4-51in sunflower rhizosphere colonization of dynamic experiments, can be colonized in the sunflower rhizosphere and root surface succeed. In addition, biocontrol strains of CF4-51also good in the Sunflower body colonization, from the sunflower stem base of5cm can detect strains of CF4-51exist.Determined the biocontrol bacterial strains culture conditions, the optimum culture conditions strain of CF4-51was28℃, initial pH6, for48h up to a maximum amount of bacteria.Though determination of the antibacterial activity of the volatile substances produced in the strains of CF4-51, we found the inhibition effect of volatile gases produced in the strains of CF4-51on the mycelial growth and sclerotia formation of Sclerotinia, and the control effect in vitro leaves is83.64%. In this study, Bacillus cereus of CF4-51produced by volatile antimicrobial substance was isolated and purified, the results show that the antibacterial substance of the volatile substances include at least18kinds of volatile substances, these substances, including alcohols, amines, alkanesnitriles and acids. Several common volatile substances pure antibacterial activity was detected and found six common substances including1-Methyldodecylamine and Acetamide,2-cyano were able to inhibit the formation of sclerotia, and found that the content of the antibacterial substance1-Methyldodecylamine is the highest.This study exploreed the correlation the sclerotia burial time and depth of the sclerotium dry weight and germination vigor, experimental results showed that with the extension of the burial time and burial depth increase, the sclerotia by the deeper the degree of decaied, NW reduced and the germinationvitality gradually lost.The analog of irrigation experiment in winter on Hetao region field found that winter irrigation could contribute to the S. sclerotiorum degradation, reduce the incidence of S. sclerotiorum effectively.