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Control of Fusarium Wilt of Cucumber by Using Nonpathogenic Fusarium oxysporum from a Suppressive Soil
|關鍵字:||Cucumber;胡瓜;Nonpathogenic;Fusarium oxysporum;Fusarium wilt;Biocontrol;Suppressive Soil;萎凋病;無病原性尖鎌胞菌;抑病土;生物防治||出版社:||植物病理學系||摘要:||
本篇論文的主要目的是在研究採自花蓮胡瓜田的土壤對胡瓜萎凋病的抑病現象、抑病因子，並從中篩選無病原性尖鐮胞菌或其他拮抗細菌，發展有效的施用方式，以供生物防治之應用。胡瓜萎凋病為台灣胡瓜栽培的重要限制因子之一。本病害可對胡瓜任何生長時期發生危害，造成幼苗猝倒、維管束褐化、成株黃化萎凋死亡和瓜果無法成熟等病徵。花蓮土經過土壤混菌法測試，確定為胡瓜萎凋病之抑病土；再經高溫高壓處理後抑病性消失的結果，推斷其抑病機制為生物性因子。從花蓮抑病土中篩選出的無病原性尖鐮胞菌Fo-366菌株，利用栽培介質混菌法育苗二星期再移植至人工病土，可有效防止病害發至生長後期；如果再混合接種更多的無病原性尖鐮胞菌株，則保護效果更為顯著。實驗室所提供的PGPR（plant growth promoting rhizobacteria）菌株，以種子粉衣法施用於胡瓜種子上，對於萎凋病並無抑制的效果，但有促進植株生長的效果。無病原性及有病原性尖鐮胞菌，在2%半乳糖替換蛋白凍的修正五氯硝基苯（pentachloronitrobenzene, PCNB）培養基上有不同呈色，可加以辨識。應用此培養特性做進一步研究結果，顯示出無病原性尖鐮胞菌Fo-366與病原菌競爭感染點，為其防病機制之一。胡瓜植株的生理表現，對於萎凋病的病勢發展有所影響，植株的老化會加速病勢的發展。
This study was aimed at verifying the suppressiveness of soil collected from a cucumber cultivation field at Hualian, determining the suppressive factor(s), screening the beneficial nonpathogenic Fusarium oxysporum and bacterial antagonists, and their application on biological control the Fusarium wilt of cucumber caused by F. oxysporum f. sp. cucumerinum. Fusarium wilt is an important limiting factor of cucumber cultivation in Taiwan. Typical wilt symptoms in cucurbits, resulting in mortality are manifested in both young and mature plants and when infection occurs at the seedling stage. The Hualian soil was proved to be a suppressive soil to Fusarium wilt of cucumber with soil infestation method in greenhouse. The possible suppressive factor(s) in Hualian soil Fusarium wilt of cucumber might be biological agents. An isolate of nonpathogenic Fusarium oxysporum (Fo-366) was screened and used to protect cucumber plants from Fusarium wilt up to harvest time by using peat moss infestation method. Moreover, if several isolates of nonpathogenic Fusarium oxysporum were applied at the same test, the protection effect would be much better. Cucumber seeds coated with strains of plant growth promoting rhizobacteria (PGPR) supplied by (Soilborne Disease lab National Chung Hsing University.), the result showed fail to protect plants from Fusarium wilt, but they were effective on promoting plant growth. The pathogenic and nonpathogenic Fusarium oxysporum produced different pigmentations and could be distinguished from each other easily when grown on a modified PCNB medium (using 2% galactose instead of 1.5% peptone). This differential medium was very useful for studying the possible mechanisms involved in the cross protection of cucumber wilt by using nonpathogenic Fusarium oxysporum. Competition of infection site was proved to be one of the protection mechanisms. Ageing of cucumber plants showed more susceptible to Fusarium wilt; the physiological changes of cucumber plants might be one of factors for the disease development.
|Appears in Collections:||植物病理學系|
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