The Study Of Trichoderma Strains Against Banana Fusarium Wilt

Hainan province, there is the biggest plantation of banana in China and is habituated to grow re-season banana plant. Banana wilt disease,caused by Fusarium oxysporum f.sp cubense, was a devastating disease. The planting area of banana was being reduced15-20%year by year in Hainan, but we are not able to utilize effective methods to control this disease. Trichoderma, widely distributed in nature, is an important organism to control plant disease. It has wide adaptability to a variety of important plant pathogens. All Trichoderma strains were isolated from banana soils from several cities of Hainan province. In order to find the good antagonistic effect strains, it has been screened by Dual Culture Test, Antagonistic Test by volatile or non-volatile substance, Potted Seedings Test and the Compathible of Banana Rhizosphere Test, the result of reasearch as follow.A number of247Trichoderma was isolated from147soil samples. Most of stains were identified as Trichoderma longibrachiatum, Trichoderma asperellum, Trichoderma koningiopsis, Trichoderma aureoviride, Trichoderma viride, the Trichoderma asperellum and Trichoderma koningiopsis were the mainly Trichoderma species. All of strains were dually cultured with Fusarium oxysporum FOC4-R2which is a pathogen to banana, and75strains were shown to inhibit Fusarium oxysporum f.sp cubense,10strains were finaly screened by antagonistic test against Fusarium oxysporum FOC4-R2, and the T2024strain was found that it has been compathible to banana rhizosphere.The result of physiology and biochemical test indicated,5strains of Trichoderma species all showed that, Catalase positive; Gelatin liquefaction positive; Amylolsis positive; Fibrinolysis positive; Pectolysis positive. There was proofed that Trichoderma species would yield a series of Hydroysis enzyme during their growth. The Chitinase test showed that10strains presented high activity of Chitinase that of the peak emerged in72hour or120hour, and the relative optimum activity temperature was45-55℃, as well as PH was6.0-7.0.The research of antibiotics test indicated that Trichoderma has a strong parasitic and spatial competition effects against Fusarium oxysporum f.sp cubense. External antagonistic test showed that the active substance of Trichoderma metabolites could well antagonistic against pathogen FOC4-R2, most of strains’inhibiton rate was up to50%, however, it was found that the average rate of inhibitory by Trichoderma’s volatile substance was better than the non-volatile substance ones. Futhermore, the strain T2024fermentation products could strongly inhibit the germinated of the pathogen FOC4-R2, when the concentration of fermentantion filtrate come to100%or50%, the inbitition rate reached above90%, and also leading the pathogen spores’shape to shrink, distortion and inflation. At last, the active substance of Trichoderma metabolites could easy to be broken by vilbration condition or at common temperature.The optimum of Trichoderma fermentation conditions were tested, the result showed that Glucose and sucrose were suitable external C sources, Yeast Extract is an ideal N source, sporulation capacity was4.7×109cfu/ml, carbon and nitrogen ratio between10:1and15:1, Adding mineral salt and shining would be good for Trichoderma sporulating, the relative optimum growth temperature was28℃, the relative optimum growth PH was6.5-7.5, the peak of sporulation were appeared to the sixth day. Moreover, on the solid culture medium of Trichoderma was found that wheat powder and race shell ratio by1:4was the optimum solid culture medium for Trichoderma when with6%inoculum25%moisture for inoculation, sporulation was the largest, up to2.8X109cfu/g.Potted seedings test showed that Trichoderma T2002, TN3, TN7, LJi, T2026, LB3, BB2, BB5, LB13and T2024have a more than70%disease control index, and Of these, Trichoderma T2024was reach to80%. Defence Enzyme test indiated that, POD, PPO, PAL activity in the plants were reach the peak in the3th to6th day after inoculated with fermentation filteredfluid of antagonistic Trichoderma and pathogen FOC4-R2. During the all test, the defence enzyme activity of treat group were obviously higher than those of control group. At last, it was confirmed that Trichoderma T2024had a strong capacity for colonization on the rhizosphere soil.