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Integrated Control of Basal Stem Rot and Stem Rot of Taiwan Anoectochilus
Chang, Sue Fen
|關鍵字:||金線連;Taiwan Anoectochilus;基腐病菌;病害防治;莖腐病菌;菌根菌;Pythium myriotylum;Pythium aphanidermatum;Pythium splendens;Fusarium oxysporum;mycorrhizaes;disease control;Rhizoctonia spp.||出版社:||植物病理學系||摘要:||
由南投縣魚池鄉及中興大學採得金線連莖基部軟腐病株，經分離及柯霍氏法則之測定後，鑑定病菌為Pythium myriotylum(Drechsler)、P. aphanidermatum(Edson)、P. splendens(＋)(Braun)。基腐病菌主要危害剛由組織培養瓶移出栽培的金線連苗，植株受害初期莖基部成水浸狀，而後軟腐，植株倒伏，病勢進展快速，相對濕度高時，會產生白色菌絲。金線連基腐病主要發生於夏季高溫多濕的季節。病害防治方面，由金線連根圈基質所分離得之14株拮抗真菌，與基腐病菌在PDA平板進行對峙培養時，皆可將三種病原菌拮抗致死。Trichoderma spp.菌株AHS-03、AHS-09、AHS-11及AHS-12及Gliocladium spp.菌株ADS-01、AHS-07、AHS-08分生孢子懸浮液(108 spores/ml)澆灌植株與栽培基質可有效防治P. myriotylum引起之基腐病害；Gliocladium spp.菌株AHS-01、AHS-02、AHS-08及AHS-10與Trichoderma sp.菌株AHS-13處理時可使種植在含P. aphanidermatum基質中植株，存活率達90％以上，而未處理者為50％；但所有拮抗菌菌株皆無法抑制P. splendens所引起之基腐病。澆灌亞磷酸1000倍(pH 6.0)，可防治上述三種腐霉病菌引起之金線連基腐病，防治效果達90％以上。由Fusarium oxysporum(Schl.)引起的金線連莖腐病，普遍發生於各栽培場，不論株齡多大皆會遭受為害，為金線連生產栽培之主要限制因子。本研究係探討利用拮抗菌及金線連菌根菌評估對莖腐病菌防治之可行性。以栽培基質蛇木加稻殼、泥炭土及燕麥粉培養拮抗真菌AHS-06，再與泥炭土混合後種植金線連，可有效抑制莖腐病之發生，防治至7個月時，存活率達88％，而對照組只有22％。由人工栽培及野生金線連根部所分離得到之菌根菌，經初步鑑定結果R-01為雙核絲核菌菌株，RC-1、RC-2、R-1m、R-5m及R-ro則為多核絲核菌，其中RC-1為AG-6菌絲融合群融合。金線連菌根菌最適生長溫度範圍為20-28℃，R-5m菌株酸鹼值為pH 6，其餘菌株皆為pH 7-9。接種於5-6個月大之金線連組織培養苗根部，48小時便可侵入根內，28天於根部形成菌根。金線連根部接種菌根菌R-01、R-1m菌株14天或RC-1菌株21天後種植，栽培至84天，可降低莖腐病之發病率。接種R-01菌株並施用Streptomyces saraceticus strain 31液劑100倍與接種R-ro菌株施用AHS-06可降低病害。金線連種植於帶菌根菌栽培基質，經84天後，只有雙核R-01菌株可減少莖腐病之發生。
Taiwan Anoectochilus plants with the basal stem rot symptoms were collected from Yiechu, Nantou and campus of NCHU. Three distinguished isolates of Pythium spp. were isolated. After satisfaction of Kocks postulates, the causal organisms were identified as Pythium myriotylum (Drechsler), P. aphanidermatum(Edson) and P. splendens(＋) (Braun). These pathogens primarily infected the seedlings soon after transplanted from flasks. The main symptoms of the basal stem rot were water-soaked, soft rot and damping-off. Under favorable disease development conditions high temperature and relation humilities, disease progressive rapidly and cottony aerial mycelial of the pathogen covered the infected plants. A total of 14 antagonistic fungi were isolated from the rhizosphere of Taiwan Anoectochilus. These isolates were dual culture against three basal stem rot fungi Pythium spp., respectively on PDA and all 14 isolates had lethal to all three Pythium spp. By spraying conidial suspension on seedling and in cultivating substrate, isolates of Trichoderma spp., AHS-03, AHS-09, AHS-11, AHS-12, and isolates Gliocladium spp., AHS-01, AHS-07, AHS-08 were able to control the disease caused by P. myriotylum. Four isolates, AHS-01, AHS-02, AHS-08, AHS-10, of Gliocladium spp. and isolate AHS-13 of Trichoderma spp., were also effective control P. aphanidermatum and increased the plant stand rate up to 90% as compared with control, plant stand rate 50%. None of the 14 isolates of antagonists could suppress the basal stem rot incited by P. splendens. The efficacy of treatment with phosphorous acid at 1000X(pH 6.0) to control pathogens of basal stem rot was reached up to 90%. Stem rot caused by Fusarium oxysporum occurs in many cultivations and is the major limiting factor for the growth of Taiwan Anoectochilus (Anoectochilus formosanus Hay.). The objective of this study is to evaluate potential antagonists and mycorrhizaes for their effectiveness to control stem rot of Taiwan Anoectochilus. Antagonistic fungus, AHS-06, was propagated in a mixed substrates including tree-fern aerial root fragments, rice hulls, peat moss and oat meal. Prior to planting Taiwan Anoectochilus, former mixed substrates were blended with peat moss again. As a result, it was significantly effective to suppress the diseases of the stem rot. The plant stand rate was 88% after 7 months planting compared with the check, plant stand rate 22%. Mycorrhizae isolated from both cultivated and wild Taiwan Anoectochilus were identified as member of the genera Rhizoctonia spp. R-01 was binucleate isolate, and RC-1, RC-2, R-1m, R-5m, and R-ro were multinuleate isolates. RC-1 belongs to anastomosis groupAG-6. The optimal temperature and pH value for mycorrhizal fungi varied from 20 to 28℃ and pH 7 to 9, except for RC-1(pH 6.0).The mycorrhizaes could penetrate into the roots 48 hours after inoculation on 5-6 months old seedlings and consequently formed mycorrhizaes on roots in 28 days. The inoculation with R-01 and R-1m for 14 days, or with RC-1 for 21 days was capable of reducing the disease incidence of the stem rot 84 days after planting. The inoculation with both isolate R-01 mixed with Streptomyces saraceticus strain 31 and R-ro mixed with AHS-06 reduced the disease severity. Inoculation of binucleate R-01 isolate in the substrate could slow down the occurrence of the stem rot of Taiwan Anoectochilus 84 days after planting.
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