Disease ecology of Fusarium wilt of loofah and its grafting control

中文摘要 本篇論文的目的是在研究源自圓筒型白絲瓜（「水蛙窟白」、「旗山白」和「赤崁頂白」）和綠絲瓜（「東光」和「農試181號」）的萎凋病菌（Fusarium oxysporum f. sp. luffae, Fol）在發生生態上的不同，溫度對絲瓜萎凋病的影響及其嫁接防治。源自白絲瓜的絲瓜萎凋病菌（Fol-114為代表），在馬鈴薯葡萄糖培養基上一致產生淡黃色素；而源自綠絲瓜的菌株（Fol-168為代表）則主要產生紫黑色素，少數產生淡黃色素（田間分離率約為7：1）。以剪根接種法測定其病原性，發現Fol-114對「赤崁頂白」和「東光」分別造成45和63% 的發病度；Fol-168對「東光」造成56%，對「赤崁頂白」卻僅有7%。以混菌土種植供試絲瓜，結果指出供試的不同淡黃色素菌株對「赤崁頂白」和「東光」造成44-88% 的發病度；紫黑色素菌株則對「東光」造成38-76% 的發病度，對「赤崁頂白」則低於8%。將供試絲瓜種植在人工（含有Fol-114和Fol-168）和天然的混菌土（水蛙窟、大坪頂和魚池地區罹病絲瓜田的田土），從發病的「赤崁頂白」之地上莖部只得到淡黃色素菌株；從「東光」則僅能分離得到紫黑色素菌株。雖然Fol-114和Fol-168在田間主要的寄主不同，但其病原性檢定的結果說明它們並不是兩個生理小種。早植（12-2月）的白絲瓜在田間感染絲瓜萎凋病菌後會發生苗枯現象，在3-4月補植者則否，卻在5月以後陸續發生成株萎凋的病徵。於溫室和生長箱中進行剪根接種試驗，在低溫（均溫低於24℃以下）的環境下，圓筒型絲瓜容易發生苗枯病徵，高溫下則否（均溫高於28℃）。在冬天的溫室氣溫（均溫23℃）下，病原菌（Fol-114）在2週內即從芽栓（peg）侵入，分離率為50%；在春天的氣溫（均溫27℃）下，病原菌的分離率降低，在第2週僅達9%，到第5週才上升至45%。1999年在水蛙窟的田間嫁接防治試驗顯示以圓筒型絲瓜（「L-39」）為根砧的嫁接苗和未嫁接的赤崁頂白實生苗發生萎凋病，其發病率介於15-61%；以稜角絲瓜為根砧的嫁接苗雖然有13-24%的發病率，卻皆因接穗（「赤崁頂白」）長出氣根接觸土壤所致。2000年在魚池地區再進行田間防治試驗，結果以稜角絲瓜美菱為根砧的防治效果及絲瓜果實的品質最優。ABSTRACT The purpose of this study was to investigate the disease ecology of Fusarium oxysporum f. sp. luffae (Fol) isolated from white (cv./line ‘White loofah-SWK', ‘White loofah-CS' and ‘White loofah-CKD') and green loofahs (cv./line ‘Cylinder' and ‘TARI No.181'), the influence of temperature on disease development and its control by resistant rootstock. Isolates Fol (represented by Fol-114) from white loofah produced light orange pigment (LO) on potato dextrose agar medium, and isolates (represented by Fol-168) from green loofah mainly produced dark purple (DP) plus a few light orange (DP/LO≒7/1). The pathogenicity tests by root-pruning method revealed that Fol-114 caused disease severity of 45% and 63% on, respectively, cvs. ‘White loofah-CKD' and ‘Cylinder', and Fol-168 caused 56% on ‘Cylinder', but only 7% on ‘White loofah-CKD'. The inoculation experiments in the pathogen-infested soil indicated that many LO-pigmented isolates caused 44-88% of disease severity on both ‘White loofah-CKD' and ‘Cylinder' loofahs, whereas the DP-pigmented isolates caused 38-76% on ‘Cylinder', but less than 8% on ‘White loofah-CKD'. Moreover, the ability of these two different pigmented isolates to colonize tested loofahs was also assayed in artificial and natural soils infested with both LO- and DP-pigmented isolates. It resulted that only LO- and DP-pigmented isolates were isolated from diseased stem of ‘White loofah-CKD' and ‘Cylinder', respectively. These two isolates (Fol-114 and Fol-168) favored different hosts in field, but according to their pathogenicity, they were not different physiological races. Seedlings of white loofah that transplanted to field around late December to February showed damping-off symptom after infected by Fol. In contrast, seedlings transplanted around March to April failed to show this phenomenon. Otherwise, the survival adult loofah plants showed wilt symptom after May. The temperature experiments with root-pruning inoculation method indicated that the wilt of cylindrical loofahs was more serious at the temperature below 24℃, but not at 28℃or above. Isolated Fol was first detected in peg two weeks after seeding in pathogen-infested soil in winter (avg. temp. =23℃) and the pathogen isolation rate was 50%. However, in spring (avg. temp. = 27℃), the isolation rate was only 9% two weeks after seeding, and it could not reach 45% after 5 weeks. Field control experiment conducted in 1999 showed that grafted ‘White loofah-CKD' by using cylindrical loofah (‘L-39') as rootstock and non-grafted ones had Fusarium wilt of 15-61%. Grafts with angled loofah as rootstock were infected by wilt pathogen through air roots of ‘White loofah-CKD' scion. In 2000, the field plots were conducted at Yuchih area, and the results revealed that grafts with angled loofah ‘Miriam' as rootstock had the best control value and fruit quality.目錄 中文摘要------------------------------------------------------------------------ Ⅰ 英文摘要------------------------------------------------------------------------ Ⅱ 誌謝------------------------------------------------------------------------------ Ⅳ 目錄------------------------------------------------------------------------------ Ⅴ 附表目錄------------------------------------------------------------------------ Ⅷ 圖版目錄------------------------------------------------------------------------ Ⅹ 前言------------------------------------------------------------------------------ 1 前人研究------------------------------------------------------------------------ 4 材料與方法-------------------------------------------------------------------- 10 一、田間病害調查------------------------------------------------------------------------ 10 二、病原菌的分離、鑑定與保存------------------------------------------------------- 10 1. 病原菌的分離---------------------------------------------------------------------- 10 2. 接種方法---------------------------------------------------------------------------- 11 3. 鐮孢菌分離株的鑑定------------------------------------------------------------- 12 4. 病原菌的保存---------------------------------------------------------------------- 12 三、病原性與寄主範圍之測試--------------------------------------------------------- 13 1. 供試植物的來源與栽培---------------------------------------------------------- 13 2. 供試菌株的來源------------------------------------------------------------------- 13 3. 寄主範圍的測試------------------------------------------------------------------- 14 4. 接種源濃度對絲瓜萎凋病的影響---------------------------------------------- 14 5. 絲瓜不同品種/系抗病性之檢定------------------------------------------------ 14 6. 病原菌的再分離------------------------------------------------------------------- 15 四、溫度對絲瓜萎凋病的影響--------------------------------------------------------- 15 1. 溫度對病原菌菌絲生長的影響------------------------------------------------- 15 2. 溫度對絲瓜萎凋病病勢發展的影響------------------------------------------- 15 3. 絲瓜萎凋病菌起始感染點的偵測---------------------------------------------- 16 五、利用抗病根砧防治絲瓜萎凋病--------------------------------------------------- 16 1. 接穗與根砧幼苗的培育---------------------------------------------------------- 17 2. 1：1頂劈嫁接苗的製作方法------------------------------------------------------ 17 3. 嫁接苗的馴化---------------------------------------------------------------------- 17 4. 田間防治試驗---------------------------------------------------------------------- 17 結果----------------------------------------------------------------------------- 19 一、田間病害調查------------------------------------------------------------------------ 19 二、病原菌分離與鑑定------------------------------------------------------------------ 19 1. 病原菌的分離與鑑定------------------------------------------------------------- 19 2. 鐮孢菌分離株的寄主範圍------------------------------------------------------- 20 3. 接種源濃度對絲瓜萎凋病的影響---------------------------------------------- 20 三、不同品種/系絲瓜對萎凋病菌的抗病檢定-------------------------------------- 21 1. 剪根接種法------------------------------------------------------------------------- 21 2. 以混菌土接種法------------------------------------------------------------------- 21 3. 病原菌的再分離------------------------------------------------------------------- 22 四、溫度對絲瓜萎凋病侵入點與病勢發展的影響--------------------------------- 22 1. 溫度對菌絲生長的影響---------------------------------------------------------- 22 2. 溫度對絲瓜萎凋病的影響------------------------------------------------------- 22 3. 絲瓜萎凋病起始感染點的偵測------------------------------------------------- 22 五、田間防治試驗------------------------------------------------------------------------ 24 討論----------------------------------------------------------------------------- 25 參考文獻----------------------------------------------------------------------- 31 附錄----------------------------------------------------------------------------- 6