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Identification and Biocontrol of Lily Scale Bulblet Root Rot Caused by Pythium spp.
|關鍵字:||Lily scale bulblet|
|摘要:||本論文之目的在於鑑定百合鱗片球根腐病之病原，和篩選拮抗細菌作為生物防治。從田間百合罹病株上分離得到之腐霉菌（Pythium spp.），計有Pythium aphanidermatum，P. ultimum，P. spinosum 和 P. splendens等四種。經完成柯霍氏法則證實上述腐霉菌主要對百合鱗片球植株具有強致病力，但對公斤球與開花球植株僅造成根尖壞疽、植株生長矮化等潛隱性病徵（subclinical symptoms）。此外從人工接種可知 P. ultimum 和 P. spinosum 最適發病溫度為16- 20 ℃ 而 P. aphanidermatum 則為 28 ℃，但這三種腐霉菌於田間百合罹病株分離率並不高。然而 P. splendens 在供試溫度16-28 ℃ 下皆對鱗片球植株具有強致病力且田間分離率高，故為百合鱗片球根腐病之主要病原。將百合罹病根部、其根圈土壤、綠力有機肥及蚯蚓排遺物等材料，加入1 % 蔗糖或1000 ppm水楊酸溶液作為處理，能夠獲得較高比率之拮抗細菌。在溫室將百合鱗片球粉衣處理拮抗細菌，並種於含腐霉菌的萬興自然病土中，以分離自百合罹病株根部代號為ADR-s-16之菌株能夠達到保護效果，但在萬興及大坪頂農場的田間試驗中並無特別顯著差異。其原因可能為台糖公司提供之鱗片球遭受污染帶有苗枯病菌（Fusarium moniliforme），或者鱗片球低溫儲藏時間不足，尚未完全打破休眠而導致田間發芽率偏低。|
The purpose of this study was to determine the cause of root rot of lily plants from scale bulblets, and screening the antagonistic bacteria for biological control. Based on completion of Koch's Postulate, the four species of Pythium including P. aphanidermatum, P. utlimum, P. spinosum and P. splendens isolated from diseased lily plants collected from fields were proved to be highly pathogenic mainly on lily plants from scale bulblets, but only produced subclinical symptoms such as root tip necrosis and stunting on lily plants from yearling and commercial bulbs. Inoculation tests also revealed that the optimum infection temperatures were 16-20 ℃ for P. ultimum and P. spinosum, and 28 ℃ for P. aphanidermatum. These three Pythium spp. were not found frequently on lily plants in fields. However, P. splendens were quite pathogenic to lily plants from scale bulblets among the tested temperatures from 16-28 ℃. Its isolation rate from field specimens was high and thus, it was identified as the major pathogen of this disease. The better isolations of antagonistic bacteria were obtained from lily diseased root and their rhizosphere soil, green-power organic fertilizer and earthworm's casting amended with 1% sucrose or 1000 ppm salicylate solution. One of the antagonistic bacterium designated ADR-s-16 isolated from diseased lily plant when coated on lily scale bulblets before planting could protect the plants against Pythium spp. naturally infested in Wan-Hsin soil in greenhouse tests. However, the results in two field trails carried out in Wan-Hsin and Da-Ping-Ding experimental farms in 1998-1999 and 1999-2000, were not significant difference. One of the reasons for no significance might be due to that the scale bulblets supplied by Taiwan Sugar Company were infested with Fusarium moniliforme or still in dormancy (the incubation period in low temperature might be not long enough to break the bulb dormancy completely) and thus, the germination rate was too low in fields.
|Appears in Collections:||植物病理學系|
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