Study On The Selection And Main Mechanisms Of Trichoderma Spp.on Rhizoctonia Solani

In this paper, 323 strains of Trichoderma spp. were separated from the soil samples of Shandong, Guangdong, Guangxi, Beijing, Gansu, Yunnan,Vietnam etc. through the flat panel dilution method. A good strain of Trichoderma spp. was gotten throught dual-culture, tolerance and control effect.The elementary biological character were mensured. The best culture medium was assured by orthogonal projection of L_g3⁴. The culture medium has malt sugar of 18 g, peptone of 6g, KH₂PO₄ of 1g, KNO3 of 1 g, VB₂ of 0.2g, agar of 20 g. When it grew in the best culture medium, the tempreture range of growth was 5～35℃, the tempreture range of hypha and spores was 15～30℃, the best was 25～30℃; the range of pH was 4～11, the best is 5,6; there was no correlation between illuminance and hypha, but illuminance was good to produce spores.T05-049 was identified as Trichoderma pseudokoningii through cultural characteristics of pycnidiophore, phialide, spore in MA culture medium.The control mechanisms of T05-049 on Cucumber seedling damping off were researched through pot incubation test. It had the ability of spatial, nutrition competing and hyperparasitism. Combinated with the separation result of fungi, it proved that T05-049 could establish rapidly in the rhizosphere of Cucumber seedling, while R15 was convers. It proved that T05-049 could inhibit R15 so as to control Cucumber seedling damping off.T05-049 could inhibit the growth of R15 through producing antibiotic substance of volatile or no- volatile antibiotic substance. No- volatile antibiotic substance was the main factor.T05-049 could increase POD, CAT, soluble protein, and reduce MDA. These could enhance the disease resistance of Cucumber seedling and lower the harmfulness induced by R15.T05-049 could lower the quantity of fungi, ray-fungi, dominant bacteria obviously. And most of them were pathogen. It proved that T05- 049 could inhibit pathogen strongly.