为了初步明确长枝木霉菌(Trichoderma longibrachiatum)对植物病原菌的抑菌谱和抑菌作用机理, 采用对峙培养和显微观察相结合的方法测定了长枝木霉菌对12种植物病原菌生长的抑制作用, 并通过显微观察的方法研究了长枝木霉菌对12种病原菌的抑菌机理。对峙培养结果表明, 长枝木霉菌对苹果树腐烂病菌(Valsa ceratosperma)和棉花立枯病菌(Rhizoctonia solani)的生长抑制作用最强, 生长抑制率分别为86.4%和72.5%, 且培养3 d后长枝木霉菌的菌落可覆盖苹果树腐烂病菌整个菌落和棉花立枯病菌菌落边缘, 并在苹果树腐烂病菌菌落表面和棉花立枯病菌菌落边缘产生大量孢子, 拮抗等级分别为Ⅰ和Ⅱ级; 对小麦叶斑病菌(Bipolaris triticicola)的生长抑制作用最弱, 生长抑制率仅为27.5%, 拮抗等级为Ⅲ级。抑菌作用机理试验结果表明, 长枝木霉菌与12种病原菌相互作用后可通过产生抑菌圈、营养和空间竞争作用、重寄生作用, 覆盖或深入病原菌菌落内部生长, 占领病原菌的生长空间, 以及菌丝与病原菌菌丝相互缠绕和交错, 且缠绕的部位出现明显缢缩, 最终使部分病原菌菌丝细胞原生质浓缩和菌丝断裂。因此, 长枝木霉菌对供试的12种植物病原菌生长均具有一定抑制作用, 并且明确了其抑菌作用机理。
To clarify the antifungal spectrum of Trichoderma longibrachiatum and the probable mechanism of T. longibrachiatum against plant pathogens, confrontational incubation and microscopic observation were used to determine the antifungal spectrum, and to explore the probable mechanism of T. longibrachiatum against twelve kinds of plant pathogens in vitro. The results of confrontational incubation experiment showed that T. longibrachiatum had the greatest magnitude of inhibition against the plant pathogens of Valsa ceratosperma and Rhizoctonia solani in vitro. The inhibitory rates of T. longibrachiatum against the plant pathogens of V. ceratosperma and R. solani were 86.4% and 72.5% respectively. It was further noted that T. longibrachiatum colony covered the whole colony of V. ceratosperma and the edge of R. solani colony, produced large numbers of spores on in whole colony of V. ceratosperma and the edge of R. solani colony 3 d after inoculation. Also the antagonism coefficient of T. longibrachiatum against V. ceratosperma and R. solani plant pathogens were ranked as Ⅰ and Ⅱ, respectively. However, the inhibitory effect of T. longibrachiatum on Bipolaris triticicola plant pathogens was weak, and the inhibitory rate was 27.5%. Meanwhile the antagonism coefficient of T. longibrachiatum against B. triticicola was grade Ⅲ. Analysis of antifungal mechanism of T. longibrachiatum showed that T. longibrachiatum produced inhibition zone, competed for nutrition and spaced with plant pathogens, and showed mycoparasitic behavior against plant pathogens when in contact with each other. Then, T. longibrachiatum mycelia covered the colonies of plant pathogens, grew on the surface and occupied the space of plant pathogens after contact with twelve pathogens. Plant pathogens mycelia appeared twisted after contact with T. longibrachiatum, and twisted part were so obviously constricted that protoplast of pathogen hyphae cell and mycelia eventually spilt and ruptured. T. longibrachiatum strains had different inhibitory effect on the growth of twelve kinds of plant pathogens which determined the probable mechanism of T. longibrachiatum against plant pathogens.