Screening Of Antagonistic Bacteria And Study Of Bio-organic Fertilizer Against Fusarium Oxysporum F.sp.Cubense

In this study, we selected four antagonistic strains from soils of different places in Hainan island. Pot experiments showed that the bio-organic fertilizers made from the four anti-strains can effectively reduce the disease incidence of banana wilt disease. Among them, we selected one strain with good antagonism ability to study the bio-organic fertilizer formula made of cow mature, rapeseed, cassava residue and eucalyptus slag. The result showed:1, Plate confrontation experiment showed the inhibition rate of WJA,WJ5,WJ22,WJ25 was 73.1%,73.3%,76.7%,77.8%respectively, These strains were all identified as B. amyloliquefaciens.. The fermentation broth of the four strains can effectively inhibit the growth of pathogen, and the inhibition ability of the four strains was WJA>WJ22>WJ5>WJ25. The fermentation broth of the strains significantly inhibited the germination rate of pathogen spore.2, 10, and 20 times fermentation broth dilutions of four anti-strains all possessed the inhibition activity, and inhibition rates were between 46.39%～83.88%, 34.44%～79.75%,18.29%～67.56%, respectively. Among them,2 times diluted fermentation broth of WJ22 showed the best inhibitory effect compared with other three strains. Volatile compounds of WJ5, WJ22 and WJ25 also showed a good inhibitory activity on pathogen growth, WJ22 showed the best inhibitory activity. Lipopeptide analysis showed strain WJ5 and WJ22 could secret iturin, surfactin and fengyin homologs, strain WJA could metabolize surfactin and fengyin, and strain WJ25 could secret bacillomycin, surfactin and fengyin during their growth stages.2, Greenhouse experiment showed that organic-fertilizers’second fermentation with antagonistic strains obtained from different banana field in Hainan island can significantly reduce the banana Fusarium wilt incidence compared with the control. Among them, the lowest incidence rate was detected in the BOF22 treatment, the control incidence was 70%. BOF22 not only suppressed Fusarium wilt but also significantly promoted banana growth, and better than other treatments.Plant height of the BIO22 treatment was 1.61 times greater than that of the OF treatment, and plant thick, leave area were 1.50,1.95 times greater in average. To test the number of bacteria, fungi and pathogen in the banana rhizosphere soils using spread plate method, results showed that numbers of bacteria was higher in the BOF treatments, and the number of fungi and pathogen was lower after 90 days. PCR-DGGE analysis of banana rhizosphere soil fungal diversity, the result showed the species Shannon-Wiener index, evenness index and Simpson’s diversity index were higher than control treatments.3, We seleced the best antagonistic strain WJ22 to study about the fomula fertilizer made of cow manure. The research showed cassava residue, repeseed and eucalyptus slag can effectively promote the fermentation of WJ22, and the best amount was 15% of the rapeseed,20% of the cassava residue,20% of the eucalyptus slag. Pot experiment using the fomula bio-organic fertilizer showed that conmbination of organic fertilizer with WJ22 can effectively promote the growth of banana.