台灣立枯絲核菌抑菌土壤之篩選

Study on the soil suppressive to Rhizoctonia solani in Taiwan

"由台灣14個縣市採集331個耕作田土壤，經測試後，只有10個土壤樣品為Rhizoctonia solani AG-4之抑菌土，僅佔3%，其中3樣品採自雲林的虎尾與斗南，2個採自屏東九如，2個採自花蓮鶴岡，3個採自台東市附近。而供試的10個森林土壤，則有3個為抑菌土，佔30%。將6個不同抑菌性土壤作接種試驗，其中2個抑菌土與2個半抑菌土均能降低蘿蔔幼苗立枯病。選取抑菌性不同的62個土壤樣品，測定pH值、有機質含量及土壤質地，經統計分析後，發現這些土壤理化性質與抑菌性無關。抑菌土對不同菌絲融合群AG-1、AG-2、AG-3及AG-4菌絲生長的抑制能力亦不一致。抑菌土對其他5種真菌與1種卵菌（包括Alternaria alternata, Curvularia lunata, Fusarium oxysporum f. sp. cubense, Bipolaris maydis, Phytophthora capsici及Sclerotium rolfsii）的抑制能力亦不同。"

"Among 331 cultivated soils collected from 14 countries of Taiwan, only 10 soil samples were defined as being suppressive to Rhizoctonia solani AG4 when the germination of monilioid cells was less than 50%. Three of these suppressive soils were collected from central part of Taiwan, two from southern Taiwan, and the other five from eastern Taiwan. Among 10 forest soils tested, three soil samples were suppressive to the pathogen. When six soils with different germination rate were selected to mix with 0.5% chopped potato-soil inoculum as infested soils, two pathogen-suppressive soils and 2 out of 3 semi-suppressive soil were also suppressive to the damping-off of radish seedlings caused by the pathogen AG-4. Based on the data of soil analysis among 62 soil samples, soil pH, organic matter content and soil texture were not correlated to the germination of monilioid cells statistically. Mycelial growth of different anamtomosis groups (AG-1, AG-2, AG-3 and AG-4) varied in different suppressive soils. In the spore germination test of six species of fungi and oomycetes on the tested soil, including Alternaria alternata, Curvularia lunata, Fusarium oxysporum f. sp. cubense, Bipolaris maydis, Phytophthora capsici and Sclerotium rolfsii, the inhibitory spectrums of suppressive soils were also different."