Effect Of Compound Antagonistic Bacteria Fermentation Liquid On Banana Fusarium Wilt And Soil Microflora

Banana wilt disease, also kown as the Panama disease or yellow leaf disease is a kind of soil-borne disease caused by Fusarium oxysporum.f sp. Cubense FOC infecting the banana plant vascular tissue, leading to a devastating vascular necrosis rotten. It has been considered as a serious threat to banana industry. Due to lack of effective resistance varieties and chemicals, safe, effective and environmental friendly biological control becomes the most potential method. In this study, the preventive and control effect of application of fermentation fluid to banana growth were investigated by conducting a comprehensive research including screening andidentification of antagonistic bacteria, screening of fermentation substrate and carbon nitrogen ratio, induction of disease resistance and soil microflora.1.139strains of antagonistic bacteria and133strains of antagonistic actinomycetes were obtained from banana wilt diseased infected soil,healthy soil,different natural cake fertilizer matrix. Strain4-L-16was isolated from rapeseed cake fertilizer fermentation fluid and T3-G-59was isolated from healthy soil in MeiTai. The two strains both have strong inhibitory effects on mycelia growth and spore germination to nine kinds of plant pathogen including FOC4. By cultivating character and bacteria morphology observation> physiological and biochemical tes、16SrDNA sequencing,4-L-16strain was identified as Bacillus methylotrophicus, T3-G-59strain was identified as Streptomyces polychromogenes.2. The aboved two strains were marked by antibiotics and they exibit stable resistance. Potted inoculation test show that4-L-16and T3-G-59both can colonize in rhizosphere soil of banana seedlings, the colonization is10cfu/g. T3-G-59can colonize in banana plant and the colonization is103cfu/g, root system has the largest number of the colonization, bulb has less, pseudostems has the least.3. The compound antagonistic bacteria4-L-16and T3-G-59were added to six kinds of cake fertilizer substrates to fermentate respectively, taking bacteria cake fertilizer substrates fermentation fluid without antagonistic bacteria as control, the results show that six kinds of fermentation fluid have significant effects on the growth of banana seedlings, the treatments with antagonistic bacteria fermentation fluid are better than that of without antagonistic bacteria. The banana seedlings root systems treated by adding antagonistic bacteria are more prosperous the above-ground morphological structure more reasonable and the aboveground absorption of phosphorus, potassium, magnesium, are superior to the substrates treatments of bean cake, peanut cake, rapeseed without antagonistic bacteria.4. The control effects of the six kinds of cake fermentation fluid with compound stains of4-L-16and T3-G-59on banana wilt disease show that soybean, peanut, rapeseed cake have the best control effects, their control efficiency reached68.22%,54.21%and57.94%respectively. Four kinds of enzyme activity are higher than that of the other three substrates, those results are the same as control effect results, suggesting that induced resistance may be one resistance mechanism of antagonistic bacterium fermentation liquid on control of banana fusarium wilt disease. Six kinds of cake fertilizer fermentation fluid microbial diversity research results indicate that wheat bran and prickly ash cake have the highest amount of microbial total bacterium, but the number of4-L-16and T3-G-59are relatively small, bean cake, peanut cake and rapeseed fertilizer fermentation fluid have obvious advantages in the amount of antagonistic bacteria、growth-promoting bacteria and antagonistic bacteria variety, ratio. So bean cake, peanut cake and rapeseed were selected as fermentation substrates to fermentate compound strain of4-L-16and T3-G-59.5. The indoor potted experiment is carried out to study the effect of the rape seed cake, soybean cake and peanut cake of different carbon and nitrogen ratio fermentation liquid on banana wilt disease control. Biolog micro plate technology was taken to study the differences of soil microbial community diversity. The results show that, all kinds of cake fertilizer can reduce the number of soil fusarium oxysporum by one quantity level. Sixty days after transplanting, the control effect of rape seed cake treatment reachs59.60%～67.25%, higher than the same C/N of soybean cake and peanut cake treatments significantly; Biolog results show that rhizosphere soil microbial community AWCD are as follows:CK>15:1(C/N)>20:1(C/N)>25:1(C/N), Me Intosh index decreased with the increasing of C/N; PCA analysis indicate that the carbon source utilization ability among the soil microbial community are similar in three kinds of cake fertilizer treatments with C/N ratio as25:1and they are obviously different from water treatment. In addition, we found that there are some obvious difference among the domiant population treated with different fermentation substrate or same fermentation substrate with different carbon and nitrogen ratio and control. Bacteria with growth-promoting effect and antagonist bacteria of Bacillus, Rhodopseudomonas, and Streptomyces existed in all kinds of fermentation fluid treatment but no in CK treatment.6. Under field condition, the Biolog and T-RFLP method is used to study the effect of comprehensive measures of soil disinfection combined with antagonistic bacterium fermentation liquid and enough Organic fertilizer on control of banana fusarium wilt disease and its prevention mechanism, results show that both cake fertilizer fermentation fluid with antagonistic bacteria and soil disinfectant can reduce disease index of banana fusarium wilt disease significantly, the highest control efficiency can reach60.82%with the combined application of those two methods. The result of Biolog eco plate show that the application of cake fertilizer fermentation fluid with antagonistic bacteria can improve soil microbial AWCD and population uniformity, the use of soil disinfectant significantly reduces the soil microbial population’s abundance and uniformity. Principal component analysis show that the soil microbial population using carbon source exhibit an increasing trend throughout the banana growing season, the main carbon sources in the early stage are amino acids, carboxylic acids, amphiphilic compounds and carbohydrates, and the increased main carbon sources in the later stage are carboxylic acids and amphiphilic compounds. Soil bacterial diversity analysis by T-RFLP indicate that the treatments of cake fertilizer fermentation fluid with antagonistic bacteria has the highest bacterial TRFs fragments, resulted from the increase of Flavobacterium, Pseudomona and Lactobacillus population in the soil. We conclude that the application of cake fertilizer fermentation fluid with antagonistic bacteria combined soil disinfectant can increase antagonistic microorganisms species, enhance soil microbial bacteria diversity, improve soil microbial ecological structure on the basis of reducing pathogen in soil, and finally control the banana fusarium wilt effectively.