【作者】 杨学辉；

【导师】 肖崇刚；

【作者基本信息】 西南农业大学 ， 植物病理学， 2004， 硕士

【摘要】 由辣椒疫霉(Phytophthora capsici Leon．)侵染引起的辣椒疫病是世界上最具毁灭性的土传病害之一，除侵染辣椒外，还可侵染茄科和葫芦科的多种作物。随着辣椒商品化生产的迅速发展，栽培措施的强化以及不同椒型品种的推广，该病已在我国各地普遍发生，造成严重的经济损失，在贵州的辣椒产区也有逐年加重的趋势。为了更有效地防治辣椒疫病，本论文对辣椒疫病的田间为害症状、病原菌的分离培养和鉴定、辣椒主栽品种的抗病性以及病害的防治等方面进行了系统研究。主要研究结果如下： 1．辣椒疫病的田间症状 辣椒疫病可为害处于不同生长阶段的辣椒植株。苗期引起幼苗立枯、猝倒。成株期导致植株根腐，根茎部产生溃疡继而引起植株萎蔫、根茎腐烂和枯萎死亡。枝干上的溃疡发展后产生黑色坏死斑，部分或环绕枝干，引起病部以上枯死。叶片受害后产生圆形、灰褐色、水浸状的坏死斑。果实高度感病，受害后腐烂，在适宜的气候条件下病果覆盖一层白色的霉层，即病菌的孢子囊，这是辣椒疫病最典型的特征。 2．辣椒疫病菌的分离和鉴定 采用选择性培养基SCA直接分离病原菌，从菌落边缘挑取菌丝尖端于斜面培养基上进行纯化并保存。共获得有效分离物67个，回接辣椒其发病症状与田间表现完全一致。 选取不同来源的5个菌株进行形态、生理生化和生物学特性等研究。结果表明，这5个菌株在CA培养基和CMA培养基上生长量大而快，CA培养基上产生孢子囊最快，2～3天即可陆续产生。CA平板上菌落白色，浓密或稀疏绒毛状，菌丝直径1～2.5μm。孢子囊形态多样，多为圆形、近圆形、长椭圆性，孢子囊平均大小为43.5～52.7×33.3～38.8μm，长宽比1.0～2.3，乳突明显，一般单乳突，偶见双乳突。单株培养不产生卵孢子。病菌生长温度范围为12℃～35℃，对浓度为1：8×10~6的孔雀石绿不敏感，部分菌株可利用淀粉作碳源。根据这些特征将这5个菌株鉴定为Phytophthora capsici Leonian。 3．辣椒主栽品种的抗疫病性 采用灌根法对源于贵州的21个辣椒主栽品种进行苗期人工接种鉴定。结果表明，对辣椒疫病表现高抗的品种有毕节线椒、雷山朝天椒、遵义朝天椒，表现抗的品种有黔椒2号、绥椒1号、绥椒2号、乌当辣椒、遵义辣椒、湘辣1号、早杂二号等7个，表现中抗的品种有6个，感病品种5个，分别占鉴定总数的14.3％、33.3％、28.6％和23.8％。西南农业大学硕士学位论文摘要旦旦旦旦旦旦旦旦旦旦旦旦旦旦旦旦旦旦旦旦旦旦旦旦旦旦旦旦旦旦旦旦旦旦里里旦旦旦旦 对湘研3号、湘研5号、湘研13号、遵义朝大椒、绥阳辣椒、花溪大辣椒和黔椒l号等7个品种进行田间抗疫病自然鉴定，结果显示，当地普遍种植的湘研系列大辣椒品种高度感病，而几个地方品种的抗病性则较好，尤其是遵义朝天椒和绥阳辣椒等干椒品种。4.防治技术 利用菌落生长速率法对10%宝丽安可湿性粉剂、72%克露可湿性粉剂、47%加瑞农可湿性粉剂、75%好速净可湿性粉剂、72%霜消可湿性粉剂、80%新万生可湿性粉剂、58%甲霜灵·锰锌可湿性粉剂等7个药剂进行室内毒力测定，结果表明，58%甲霜灵·锰锌可湿性粉剂、72%克露可湿性粉剂、80%新万生可湿性粉剂的抑菌效果较好，抑制中浓度(E CS。)分别为8.8助留m!、8.6加g/ml与8.8如g/m!，10%宝丽安可湿性粉剂对辣椒疫霉菌无抑制作用。 将室内毒力测定筛选出的抑菌效果较好的72%克露可湿性粉剂、58%甲霜灵·锰锌可湿性粉剂、80%新万生可湿性粉剂二个药剂进行田间小区药效试验，结果表明，72%克露可湿性粉剂500倍和58%甲霜灵·锰锌可湿性粉剂500倍的防治效果较好，防效分别达到82.9%和80.2%。同时，以58%甲霜灵·锰锌可湿性粉剂500倍为试验药剂，就不同施药时间和施药次数等防治技术进行对比试验，结果显示，在辣椒疫病发病初期喷药3一4次较好，而在辣椒地完全无病株出现时施药，防效并不高于在发病初期施药.关键词:辣椒疫病病原鉴定抗病性防治更多还原

【Abstract】 Phytophthora blight of pepper, caused by Phytophthora capsici Leonian, is one of most destructive soil-borne disease in the world. P. capsici is also pathogenic on several solanaceous and cucubit hosts except for pepper. The incidence of Phytophthora blight on pepper occurs popularly in China due to the rapid commercial development of pepper production, improvement of cultivated measures and the extension of different cultivars. Meanwhile, this disease on severity has increased yearly and caused significant economic loss in Guizhou province. In order to control the disease effectively, some researches including field symptom, isolation, purification and identification of isolates, resistance of pepper cultivars currently available have been evaluated in this article. The major results are listed as follows.1. Symptoms of pepper phytophthora blight in fieldThe pathogen can infect pepper at different growth stages beginning with damping-off of seedlings in seed beds. Symptoms in adult plant include root decay; stem cankers on the main stem near the soil-stem interface cause blight, collar rot and wilt; cankers on branches cause partial or entire black spots of the plant and wilt of branches above the spots; leave spots are circular, grayish brown, and water-soaked, and fruit rot are typically covered with white sporangia of pathogen. Fruits are highly susceptible and, in certain environment, fruit rot implicates the most important sign of the disease.2. Isolation and identification of pathogenThe pathogen was isolated using selective medium RCA. Total 67 effective isolates were obtained and purified through cutting the top of mycelium of colony into slope media. The isolates were preserved in paraffin oil or sterile water. Inoculation in green house with pepper seedlings indicated that the isolate were able to infect pepper and cause similar symptom with plants in field.Morphology, physiology and biochemistry, and biological characters were tested on five isolates from different places. The results showed that the pathogen had better growth rate on CA and CMA. CA was best for producing sporangia in 2~3 days. Colony on CA was white and dense or sparsefluff-like. The diameter of hyphae was l~2.5m. Sporangia morphologies were different. The mean size of sporangia was 43.5~52.7 33.3~38.8m, and the ratio of length and breadth was 1.0~2.3. Sporangia have conspicuous papilla, usually single, sometimes double. Oospores were not produced when single cultured. All isolates could grow from 12, and showed little sensitivity to malachite green (1:8 106) .The capability of utilizing starch varied in different isolates. According to the characteristics of Phytophthora sp., these isolates were identified as Phytophthora capsici Leonian.3. Resistance of pepper varietiesPouring sporangia in soil was used to screen resistance to phytophthora blight among 21 pepper cultivars, which come from Guizhou province. The results showed that Bijiexianjiao, Leishanzhaotianjiao, Zunyichaotianjiao were highly resistant. Qianjiao-2, Suijiao-1, Suijiao-2, Wudang pepper, Zunyi pepper, Xiangla-1, Zaoza-2 were resistant varieties. 6 varieties were middle-resistance and 5 varieties were susceptible. The ratio was 14.3%, 33.3%, 28.6%, 23.8%, respectively.The results of 7 peppers on screening resistance to pepper phytophthora blight in field showed that serial varieties of Xiangyan were highly susceptible, and local varieties such as Zunyichaotianjiao, Xiangla-1 and Suiyanglajiao had better resistance, especially dried pepper varieties.4. Control techniquesGrowth rate method was used to test virulence to P. capsici of fungicides in vitro, such as Cymoxanil, Mancozeb, Kasumn-Bordeaux, Polyoxin A, Metalaxyl, Cymoxanil, Metalaxyl and Mancozeb had better inhibiting effect, the EC50 were 8.80 g/ml, 8.67g/ml and 8.84g/ml, respectively. Polyoxin A was ineffective to P. capsici.Plot test of three fungicides selected in vitro was carried out.The results showed that 58% Metalaxyl WP500X and 72% Cymoxanil WP500X could control disease effectively, and control effic更多还原