| Summary: | 碩士 === 國立中興大學 === 植物病理學系 === 91 === 柒、英文摘要
In this study, Gliocladium sp. isolate SG22 was chosen as the tested fungus, which had stronger antagonistic ability to Rhizoctonia solani AG4 and potential to produce amount of chlamydospores. Using SM medium as basic medium plus 3% grinded oat and 0.3% yeast powder was proven the best culture condition for the mass-producing chlamydospores. After 6 days the matured and similar-sized chlamydospores would be produced as 8-10X107 cfu/ml and 8-11.5 m spores. The application of using SG22 fermentation liquid affected the plant growth. Based on the soaking method, the primed seeds of cabbage and cucumber was treated with SG22 fermentation liquid. This treatment could promote plants growth significantly: drenching cabbage seedlings with high concentration of fermentation liquid will inhibit plants growth; however, drenching 2000x dilution rate of fermentation liquid will not inhibit but promote plant growth significantly. In the biocontrol aspect, the drenching and soaking methods was adopted to control cabbage damping-off caused by R. solani AG4, but there was no significant effect. However, it had a significant effect to control Rhizoctonia damping-off by mixing SG22 fermentation liquid in the AG4-infested peat moss with 5000X (w/v) dilution rate in three days. However, using soaking method to control Pythium damping-off on cucumber brought in a significant effect. When SG22 dual-cultured with R. solani AG1, AG4 and Pythium aphanidermatum, the expression of exochitinase and endochitinase could be detected. When culturing SG22 with the death cell wall of AG4, we could be detect one 122kDa exochitinase, one endochitinase and one 40kDa chitosanase. According to the result, we concluded that when SG22 antagonize to plant disease fungi, in addition to antibiotics, the chitinases might play an important role in biocontrol.
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