| Inhibiting activities of six introduced Trichoderma strains and their inhibiting substances on Sphaeropsis sapinea, Cylospora chrysosperma, Alternaria alternate, Fusarium sporotrichoides, Rhizoctonia solani, Fusarium oxysporum, Pythium debaryanum and Cenangium ferruginosum were researched by means of forest pathology, fungal science, molecular biology and biochemistry. Biological characteristics of strain T-43, which was high-effective and broad-spectrum, was studied. The taxonomic status of strain T-43was verified by the method of molecular biology. Preliminary study of the antifungal mechanism of the ethyl acetate extract, extracted from strain T43, on pathogenic fungi was done from the perspective of the impacts of the extract on three kinds of protective enzyme activities. Spore suspension and ethyl acetate extract of strain T-43were used in field application. The results show as follows:(1) Six Trichoderma strains all have higher antagonistic effect on pathogens of seedling damping-off. Ethyl acetate extracts of different strains also have inhibiting effects on pathogens of seedling damping-off, especially on Rhizoctonia solani. Strain T-43is the most effective and broad-spectrum among the six strains.(2) Strain T-43is Trichoderma virens, which ITS sequence length is589bp, GenBank accession number is HM046564. To strain T-43, the optimum carbon source is glucose, the optimum nitrogen sources is ammonium tartrate, pH5, and the optimum growth temperature is25℃(3) Ethyl acetate extract of T-43can reduce the activities of three kinds of protective enzyme of8pathogens. SOD activity decreased significantly.(4) Strain T43can significantly control the damping-off of Larch and Korean pine, at the same time, can obviously improve the growth of seedlings, increased soil microbial populations and soil enzyme activities significantly. Liquid agents (ethyl acetate extract) is suitable for larch seedlings and spore suspensions for Korean pine seedlings. |
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