| Banana wilt disease, caused by Fusarium oxysporum f.sp cubense,was a devastating disease.Currently, 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 with various mechanisms against them. By using an improved Mading Shi Bengal medium,a number of 344 Trichoderma was isolated from 206 soil samples. All of the 344 Trichoderma strains were dually cultured with Fusarium oxysporum FOC4-B2 which is a pathogen to banana,and 96 strains were shown to inhibit Fusarium oxysporum f.sp cubense,10 strains were finally screened by antagonistic test against other Fusarium oxysporum.one of them was more compathible to banana rhizosphere.Measured the population dynamics of Trichoderma T-C2 and the pathogen FOC4-B2 in sterile soil, I identify Trichoderma T-C2 has a relatively strong rhizosphere colonization ability and has a better antagonistic effect against FOC4-B2 in sterile soil; the reduction of banana disease incidence was 90%.Trichoderma, T-C2,T-H3,T-H6,T-H8,T-H11,T-H12,T-R2 and T-W11 have a more than 60% disease control index.Of these, trichoderma T-C2 has a disease prevention index of above 90%; Trichoderma has a disease control rate of up to 30% in field trials.The carbon, nitrogen, carbon and nitrogen ratio, pH, incubation time, temperature and water content of solid culture medium on Trichoderma T-C2 were tested.The result showed that Glucose and sucrose are suitable external C sources, beef extract is an ideal N source, sporulation capacity was 4.0×109cfu/ml, carbon and nitrogen ratio between 15:1 and 20:1,spore reach 4.8×109cfu/ml. Trichoderma could spore well under pH=6,6.5 and 7.0, spore reach 2.5×109cfu/ml, spore were changing with the pH value changes; temperature 15℃,20℃is too low for Trichoderma growth,25℃,28℃is more suitable for the growth of Trichoderma, with sporulation capacity of 5×109cfu/ml,30℃or 35℃was higher incubation temperature, mycelia of Trichoderma cultured under 35℃was a bit yellow. When ferment Trichoderma, the green spores began to appear at the third day, spores were more green at the sixth day, growth and reproduction of Trichoderma began to fall at the eighth day, growth rate decreased at the tenth day, indicating medium nutrients have been depleted, therefore suitable fermentation period was eight day.Under optimal conditions, the spores of liquid seed culture medium reach 109cfu/ml, with 15 to 20 percent on average spore inoculum, solid medium could reach 6.0-8.0× Under optimal conditions, the spores of liquid seed culture medium reach 109cfu/ml, with 15 to 20 percent on average spore inoculum, solid medium could reach 6.0-8.0×109cfu/ml; when with 15% inoculum,40% moisture for inoculation, sporulation was the largest, up to 8.0×109cfu/ml.The test of antibiosis of Trichoderma showed that competitive inhibition, parasitic and antibiotic effects were the main mechanism against Fusarium oxysporum f.sp cubense. Trichoderma has a strong parasitic and spatial competition effects against Fusarium oxysporum f.sp cubense.active substance in Trichoderma fermentation liquid could store at room temperature, after 15 days,they were still antagonistic against Fusarium oxysporum f.sp cubense, the active substance of Trichoderma metabolites could not be broken at room temperature, but damaged by heating; FOC4-B2 fermentation products had a slight inhibition on Trichoderma, Trichoderma could grow well on FOC4-B2 fermentation product,while FOC4-B2 could not grow well under Trichoderma fermentation product. volatile substances of Trichoderma strains have some inhibitory effect on pathogens, but all Trichoderma strains showed inhibition rate less than 50%,lower than non-volatile substances of Trichoderma.
|
PDF Full Text Request