| Summary: | 碩士 === 國立屏東科技大學 === 植物保護系所 === 98 === The purpose of this research was focused on ultilization of Trichoderma antagonists alone or amended in pangolagrass compost to test the control efficiency of cabbage seedling damping-off. A total of 29 isolates of Trichoderma spp. were isolated from soils and dead materials of plant at different areas in Pingtung. With cellophane antagonism test and dual culture, the antagonistic activity of these Trichoderma isolates was tested, and 3 isolates of Trichoderma spp. were selected based on the inhibitory effect on mycelial growth of Rhizoctonia solani AG-4, pathogen of cabbage seedling damping-off. These three antagonistic Trichoderma isolates, designated TML, TSR and TCL, could also inhibit mycelial growth of Lasiodiplodia theobomae, Pestalotiopsis euginae. Cylindrocladium sp., Colletotrichum gloeosporioides, Phytophthora capsici and Sclerotium rolfsii. Dual culture on slide between Trichoderma sp. and R. solani AG-4 showed that TML, TSR and TCL isolates could degrade the mycelium of R. solani; in addition, the hypha of Trichoderma isolate TCL could penetrate into hypha of R. solani. All of three isolates were identified as species of Hypocera koningii (anamorph: Trichoderma koningii) by comparation of the sequence of ribosomal DNA. In composting process of pangolagrass, through monitory changes of the temperature, pH value, electronic conductivity, population dynamic of microognisms, microbial activity and seed germination test in extract of compost, a mature compost could be made after 35 days fermentation. On the agar medium plates made of extract of pangolagrass compost amended with various nutrients, the mycelial growth of the T. koningii isolates was increased when rice bran or wheat bran was amended; and the sporulation was also increased when rice bran, whole wheat flour, or soybean flour was amended. The spores produced from culture of compost extract had spore germination rate of 92% or more. Isolates TML, TCL and TSR could grow well on pangolagrass compost amended with wheat bran, rice bran or wheat flour, but not with chitin amendment. When 9% wheat grain which had been grown T. koningii TML isolate was amended to diseased soil that was infested with 5% R. solani culture materials, T. koningii TML could control 100% damping-off, while 5% T. koningii TSR could control damping-off completely. When R. solani infested soil was added with 10% pangolagrass compost which had been grown T. koningii TML or TSR isolate, the control efficiency of seedling damping-off was at 21 or 33% respectively, whereas with 20% compost amendment, 73 and 82% of control efficiency, respectively.
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