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Characteristics for Inhibition of Cucumber Damping-off Pathogen by Spent Forest Mushroom Compost
|關鍵字:||Agriculture wastes;胡瓜猝倒病菌;cucumber damping-off;culture medium;spent forest mushroom compost;suppressive medium;water-soluble filtrate;農業廢棄物;香菇太空包堆肥;栽培介質;抑病介質;水溶性浸出液||出版社:||植物病理學系||摘要:||
利用四種香菇生長基質資材與香菇太空包不同腐熟程度之堆肥栽培胡瓜幼苗，發現完熟的香菇太空包堆肥（Spent forest mushroom compost；SFMC）最適於胡瓜幼苗的生長，故本試驗選SFMC作為栽培胡瓜幼苗的介質。將胡瓜猝倒病菌Pythium aphanidermatum Pa104和Pa105菌株以四種方法接種於SFMC與荷蘭泥炭苔（Bas Van Burren No.4 peat moss；BVB ）兩介質中，結果發現游走子接種法可以穩定測出SFMC抑制胡瓜猝倒病發生的效果比BVB優異。將SFMC與BVB按不同比例混合後，接種P. aphanidermatum Pa104 和 Pa105菌株，結果發現介質中含有SFMC比例愈高，胡瓜發生猝倒病的百分率愈少。將本菌Pa104 和 Pa105兩菌株接種在SFMC中，14天後，菌體的存活率降至10%以下，直到第28天時，便無法測得P. aphanidermatum 兩菌株的存活，證明本菌不易在SFMC中存活 。熱蒸汽（100℃，20min）與高溫高壓（121℃，15lb，20min）處理無法有效破壞SFMC抑制胡瓜猝倒病的功效。探討SFMC與BVB兩介質之水溶性浸出液對本菌兩菌株產生游走孢子囊、游走孢子、藏精器、及藏卵器的影響，結果發現SFMC水溶性浸出液較BVB浸出液更具有顯著抑制本菌產生游走子、藏精器及藏卵器的效果；然而，兩介質的水溶性浸出液對本菌產生游走孢子囊的數量間卻無顯著差異。本菌兩菌株游走子的釋放量隨SFMC之電導度（EC）下降而增加。在SFMC與BVB的EC值相近時，兩菌株的游走子釋放量亦隨之趨於相近。pH值不會影響兩介質浸出液的電導度；惟pH值介於7至9間，SFMC浸出液對本菌兩菌株之發芽管的抑制效果最為顯著。高溫高壓處理兩介質後抽取水溶性浸出液或由介質抽取浸出液經高溫高壓處理，皆可部份紓解兩者水溶性浸出液抑制病原菌發芽管的生長，惟介質先經熱處理再抽取浸出液者，其抑制病原菌靜止子之發芽管生長的效果較為顯著。本菌在熱處理過之SFMC中，亦比在BVB介質中不易存活。利用SFMC培育之胡瓜根、莖及子葉較BVB所培育者更具有抵抗P. aphanidermatum纏據的效果；惟兩者所培植之胡瓜根系經蒸餾水漂洗後的抗菌效果，即會隨之下降，致使本菌纏據植體的比率因而提高。SFMC所培育之植株的根與莖比BVB所培育者含有較高量的過氧化酵素活性，惟由SFMC所培育之胡瓜子葉卻比BVB培植者含有較低的過氧化酵素活性。此外，由SFMC培育之胡瓜子葉含有K、Ca、Mg、NO2--N和NO3--N的量均顯著較BVB所培植者高。綜合上述研究成果證明香菇太空包堆肥抑制胡瓜猝倒病菌的原理主要歸因於非生物因子扮演著重要的角色。
Of the four agriculture wastes tested, spent forest mushroom compost (SFMC) was more suitable as substrates for growth of cucumber seedlings than raw growth medium for cultivation of forest mushroom (RGM), raw spent forest mushroom growth medium (RFM), and raw spent forest mushroom growth medium contaminated with other microorganisms [ RFM (C) ]. Inoculation method of zoospore suspension provided a stable and accurate means of assessing the effect of SFMC and Bas Van Burren No.4 peat moss (BVB) on damping-off incidence of cucumber seedlings. SFMC was more effective in suppressing damping-off of cucumber seedlings caused by Pythium aphanidermatum isolate Pa104 and Pa105 as compared with BVB. Five SFMC-BVB medium combinations were prepared by mixing SFMC with BVB at rates of 4:0, 3:1, 2:2, 1:3, and 0:4 (v/v) and inoculated with zoospore suspension of the pathogen. The more concentration of SFMC the medium was amended, the less incidence of damping-off the cucumber seedlings were grown in the medium for 12days. SFMC was not suitable for survival of P. aphanidermatum isolates Pa104 and Pa105 because the fungi could not be detected by Corn meal-pimaricin-rose bengal-streptomycin-benomyl agar 28 days after their perlite inoculum were added into SFMC medium. The suppressive effect of SFMC medium on infection of cucumber seedlings by P. aphanidermatum isolates Pa104 & Pa105 was not reduced after it was steamed at 100℃ hot air for 20 min. or autoclaved at 121℃, 15lb, for 20 min. The water-soluble filtrate extracted from SFMC could markedly inhibit formation of oOgonia and antheridia of P. aphanidermatum isolates Pa104 & Pa105 and reduce production of zoospores as compared with BVB's water-soluble filtrate. However, filtrates from SFMC and BVB were not significantly different in affecting the formation of zoosporangia. The electrical conductivity values of SFMC filtrate were highly correlated with production of zoospores by the pathogen. The inhibitory effect of filtrate from SFMC medium were partially nullified after it was steamed and autoclaved. However, the steamed and autoclaved SFMC medium still showed adverse effect on survival of the pathogen. Cucumber seedlings grown in SFMC medium were more effective in inhibiting colonization of root, stem, and cotylendon by the pathogen than ones in BVB medium. The peroxidase activity, nutrient elements such as K, Ca, Mg, NO3--N and NH4+-N in root and stem from cucumber seedlings grown in SFMC medium were significantly higher than those in BVB medium. The results suggest that abiotic factors may play an important role on reduction of damping-off incidence of cucumber seedlings in SFMC medium.
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