【作者】 董伊丹；

【导师】 黄俊斌；

【作者基本信息】 华中农业大学 ， 植物病理学， 2008， 硕士

【摘要】 褐斑病是一种重要的草坪病害,常在草坪上造成大块褐色或黄色的病斑。严重影响草坪景观,破坏草坪质量。目前对该病的研究仍仅限于病害的调查和初步的化学防治,国内还未见有较系统的研究报道。本研究旨在确定引起高羊茅褐斑病的病原,了解病菌的寄主范围、生物学特性、病菌对高羊茅的侵入过程以及进行杀菌剂的盆栽药效试验。研究结果如下:从华中农业大学的高羊茅发病植株叶片上分离菌株Rhizoctonia sp.,用菌丝悬浮液接种高羊茅叶片进行致病性测定,证实Rhizoctonia sp.为致病菌。该菌在PDA培养基上培养2d后,菌落稀疏呈毡状,菌丝从白色到浅黄色、灰色,成熟时略呈褐色,直径4-13μm,具直角分枝,菌丝分隔处有缢缩。新生菌丝细胞为多核。菌核颜色从浅白到灰色、褐色或黑色;圆形或不规则形,单生或聚生,绒毛状。rDNA-ITS测序结果与GeneBank中的序列进行同源性比较发现菌株与Rhizoctoniasolani的同源性最高,达99%。根据形态学特征和分子鉴定结果,确定该病原菌为Rhizoctonia solani。寄主范围测定结果表明,该菌可侵染狗牙根、黑麦草、高羊茅、早熟禾、水稻、小麦、玉米、包菜、棉花、辣椒和白菜型油菜。来自于高羊茅、水稻、玉米、小麦上的4种丝核菌交互接种结果表明,除禾谷丝核菌在28℃对4种植物不能致病,其它3种丝核菌均可对4种植物进行交互侵染。病原菌生物学特性研究结果表明,该菌株在10-30℃的范围内均能生长,30℃为菌丝生长最适温度,36h后菌落直径达5.05cm。病菌在pH值为4-12的PDA培养基上菌丝均能生长,其中以pH=7生长最快,36h菌落直径为6.3cm。病菌能够有效利用多种碳源和氮源,但不同碳和氮源对病原菌菌丝生长有显著的影响。以淀粉为碳源和以酵母膏为氮源时菌丝生长最快,6d后菌丝干重分别为0.4151g和0.5276g。病原菌菌丝和菌核的致死温度分别为50℃和55℃,10min。用菌丝块对离体高羊茅叶片接种,对不同时间点样品进行组织透明、染色,观察病原菌对寄主植物的侵染过程。结果表明:接种3h后,R.solani菌丝在叶片上纵向生长,然后形成侵染垫或裂状附着胞,侵染垫由分枝菌丝聚合形成,裂状附着胞由顶端具有圆裂片的短的、肿胀分枝组成。通常病菌可以通过表皮和气孔两种途径侵入寄主,其中以穿透表皮直接侵入入主,接种6h后,在叶表皮细胞中发现有少量侵入菌丝;接种48h,叶片呈水浸状腐烂。PDA平板抑菌实验结果表明,供试五种药剂在设置的不同浓度下对病原菌的生长都有一定的抑制作用,其中30%爱苗乳油和40%福星乳油对菌丝生长有很好的抑制效果,而5%井冈霉素可溶性粉剂抑制效果最差。盆栽药效试验结果表明,在发病前施药的处理中,以5%井冈霉素和20.67%万兴乳油防病效果最好,防效分别为73.67%和70.2%;在发病后施药处理中,以30%爱苗乳油和40%福星乳油防病效果最好,防效分别为68.48%和61.57%。更多还原

【Abstract】 Brown patch,which caused symptoms of large brown or straw-coloured patches was a common serious disease on turfgrass in recent years.The outbreak of this disease led to the lack of delight,and quality of golfground.At present,there were a few reports about the investigation and chemical control of brown patch.The objective of this reseach was to indentify the causal agent of Festuca arundinacea brown patch, determine the host range,biological characteristics,the infection process of the pathogen on Festuca arundinacea leaves and screen the fungicides in pot experiment. The results showed as follow:Rhizoctonia sp.was isolated from diseased leaf of Festuca arundinacea in Huazhong Agricultural University.Pathogenicity was tested by inoculating the leaf with mycelial suspension of Rhizoctonia sp.,the result indicated that Rhizoctonia sp.was determined to be the pathogen of Festuca arundinacea brown patch.According to morphological observation,the colonies of pathogen turned to sparse felty texture after 2 days of incubated on PDA medium.Mycelium was variable in colour of white,yellow and grey,and usually maturing to some shade of brown and from sparsely aerial to mealy or felted.Branching of the main or runner hyphae was mostly right-angled,with constrictions where they originate and septate above the junction.The diameter of the runner hyphae was 4-13μm.Young hyphae were multinucleate.Comparion with sequence of ITS1-5.8SrDNA-ITS4 in Genbank showed 99%of identity with R.solani. According to the morphological characteristics and anaysis of rDNA-ITS,the pathogen was identified as R.solani.the pathogen could infected Cynodon dactylis,Lolium perenne,Festuca arundinacea,Poa pratensis,Oryzae sativa,Triticum aestivum,Zea mays,Brassica olerace,Gossypium hirsutum and Capsicum annuum.Test of cross inoculation showed that Rhizoctonia spp.were isolated from different plants,and three R.solani,isolates were are pathogenic to four tested plants at 28℃whereas R.cerealis was not pathogenic to them.The results of biological characteristics revealed that the mycelium of pathogen could grow in the range of the temperature from 10-30℃,the optimal temperature and pH value mycelial growth was 30℃and 7.The range of pH value for mycelia growth were 4-12.The pathogen could utilize various carbon and nitrogen sources,but effects of carbon and nitrogen sources for mycelial growth were significant different.Among the tested carbon and nitrogen sources in Czapek liquid medium,starch and yeast extract were best most favorable.The lethal temperature for mycelial growth and sclerotia germination were 50℃and 55℃for 10 min,respectively.Detached leaves of Festuca arundinacea were inoculated with mycelial suspension of R.solani and incubated at 28℃under high humidity.Samples were collected from inoculated leaves at different timing intervals,and then decolorated and stained.Finally,the infection process on leaves of Festuca arundinacea were observes with optical microscope.The result indicated that hyphae could grow longitudinally along leaves at 3h after inoculation.Some of branches turn to infection cushions or lobate appressoria.Infection cushions were formed via the aggregation of hyphal branches.Lobate appressoria were composed of many short and swollen branches with apical lobes.The mycelia could penetrate into leaves tissues directly or via stomata. The way of direct penetration into epidermis was frequent.Some hyphae in epidermis were found at 6h after inoculation.Inhibition of mycelia growth of R.solani by five fundicides was assayed on amended PDA medium.30%Armure EC had the highest inhibitory effect with the 50% effective concentration(EC₅₀) at 0.00613ug/ml whereas 5%jinggangmycin SP had the lowest mycelial inhibition with EC₅₀ values of 61.46369 ug/ml.Potted experiment for disease control indicated that the significant effect was observed with 5%jinggangmycin SP of 73.67%efficacy,and 20.67%Charisma EC of 70.2%in the treatment of spraying fungicide before inoculating.30%Armure EC and 40%Fiusilazole EC was 68.48%and 61.57%disease suppression in the treatement of spraying fungicide after inoculating,respectively.更多还原