Identification And Screening Of Biocontrol Strains Of Thichoderma Spp.

125 isolates of genus Trichoderma were isolated from mushrooms, plant nematodes and plant rhizosphere soil in Fujian province. Five species of Trichoderma were identified as T. harzianum, T. viride, T. koningii, T. pseudokoningii and T. longibrachiatum by morphology and culture feature. The predominant species were T. harzianum and T. viride in plant rhizosphere soil, T. koningii and T. pseudokoningii on the mushrooms, T. viride on plant nematodes.4 isolates of genus Trichoderma were screened out from 100 isolates by biomass test and antagonistic test against Colletotrichum musae, Fusarium oxysporum f. sp. niveum, Rhizoctonia solani and Botrytis cinerea on PSA medium.They were T. harzianum TGy040604, T. viride TGc050601, T. viride TGc050609 and T. viride TZxj050610. The biocontrol mechanisms of these strains were competitive inhibition, parasitism and antagonism to plant pathogens. The parasitism of Trichoderma was discovered to B. cinerea and R. solani but had no parasitism to C. musae and F. oxysporum in the research. The results showed that Trichoderma had parasitical specialization to plant pathogenic fungi.The study of active metabolites of Trichoderma showed that the parasitism of Trichoderma to Root-knot nematode eggs was positive relatively with the chitinase activity. Antagonistic protein (>10000Da) and small molecular substance (<10000Da) had antifungal activity were detected in fermentation broth. Antagonistic protein and water-soluble small molecular substance obviously inhibited the growth of germ tube and hypha of C. musae. Fat-soluble small molecular substance obviously inhibited spore germination of C. musae, and the strength of inhibition was related to the concentration of fat-soluble small molecular substance. The active metabolites in broth were stable in different pH, and antifungal activity could last more than 2 months at room temperature. The results showed that the formation of antifungal substance in fermentation broth was affected with the fermated time, the inhibition activity was the highest at the 9th day.The study of culture condition of TGy040604 showed that PSA was the optimum culture medium, 28℃and pH 6.0 were the optimum growth temperature and acidity, glucose and beef extract were the optimum carbon source and nitrogen source. A given concentration of vitamin, boron, magnesium and aluminum were beneficial to the mycelial growth and sporulation of strain TGy040604. Urea, manganese, copper and zinc could inhibit the mycelial growth and sporulation. Adding mycelial powder of C. musae to solid culture medium could increase the sporulation quantity of strain TGy040604. Adding F. oxysporum f. sp. niveum to liquid culture medium could increase the biomass and sporulation quantity of strain TGy040604.The strain TGy040604 could promote plant growth and control disease. Tamato seed soaked with 1:100 dilution of original fermentation broth of TGy040604 could increase germination rate and germination vigor, cucumber seed soaked with 1:200 dilution of original fermentation broth could promote the seed germination and plant growth. Fermentation broth of TGy040604 could control C. musae, the evident control effect to banana anthracnose was obtained by inoculating the spore suspension of C. musae after spraying fermentation broth of TGy040604 on banana fruit for 24 h.