【作者】 郑艳；

【导师】 叶华智；

【作者基本信息】 四川农业大学 ， 植物病理学， 2007， 硕士

【摘要】 白芷斑枯病是四川地道中药材白芷叶部最为严重的病害，该病由白芷壳针孢菌(Septoria dearnessii Ellis et Everhart)引起。本文首次较系统的研究了白芷斑枯病菌的生物学特性、侵染过程、侵染条件、侵染源及田间发生动态，以及室内药剂的筛选。研究结果如下：一．白芷壳针孢(S．dearnessii)的生物学特性菌丝生长和产孢的温度范围为10—35℃，最适温度为25℃；最适pH5—7；病菌在PDA培养基上能够很好的生长和产孢；对碳源的利用以双糖最佳，对氮源的利用以无机氨态氮最好；光照对病菌的生长和产孢无显著影响。分生孢子在无菌水中的萌发率极低，加入糖分或寄主汁液可以显著的提高孢子的萌发率；分生孢子萌发的温度范围为10—35℃，最适温度为25—28℃；相对湿度93％以上分生孢子才能萌发，在水中孢子萌发率最高，达93.67％；pH5—7最有利于孢子萌发。在最适条件下，病菌孢子8h开始萌发，24h萌发率达到90％以上。光照对分生孢子的萌发无显著影响。分生孢子的致死温度为50℃(10min)。二．白芷壳针孢(S．dearnessii)的侵染过程采用活体叶片接种、组织学染色技术和光镜观察方法研究了该菌侵染白芷的过程。结果表明：白芷壳针孢(S．dearnessii)的分生孢子在叶片表面萌发，形成分枝的菌丝，以菌丝作为侵染结构。病菌可以通过表皮和气孔两种途径侵入寄主，其中以直接穿透表皮侵入为主，菌丝在侵入细胞时，不形成附着孢。菌丝侵入叶肉组织后可继续穿过多个细胞向深层发展，不断的产生新的分枝。被侵染的细胞内先出现颗粒状，然后慢慢变空，最终细胞死亡，导致叶片的表面出现斑点。三．白芷壳针孢(S．dearnessii)的侵染条件白芷壳针孢侵染白芷的温度范围为10—30℃，最适发病温度为25—30℃，此时潜育期最短，为12d，病斑数量最多，病情发展最快；保湿时间范围在12—48h时，植株均能发病，最佳保湿时间为24—48h，其潜育期最短。白芷壳针孢在老叶上比在新叶上更容易侵入，老叶更利于其侵入，叶龄越大侵染率越高。四．白芷斑枯病侵染源及田间发生动态调查结果表明：在四川遂宁的环境条件下，田间病残体和留种株上的病菌不经过越冬，在当年直接侵染白芷秋播的幼苗，11月初已经可以在田间见到白芷斑枯病的发生，随着温度降低进入冬季后，病情发展缓慢，当来年气温升高，病情开始发展并不断加重。从当年11月到次年2月初，由于处于冬季，温度低，病害发展比较缓慢；2月到4月，随着温度的缓慢回升，病情发展逐渐加快，病情指数不断升高；4月到7月，温度不断的升高，病情发展迅速，并于7月初，病情指数达到最高，为52.68；7月以后，虽然温度仍然还在升高，但白芷进入了生育的后期，因而病情随着白芷生长发育的停止而停止发展。病菌遇雨水，分生孢子从分生孢子器中释放出来，随水滴飞溅而传播，分生孢子侵入发病后，病斑上形成新的分生孢子器和分生孢子，进行重复侵染，扩大蔓延为害。病害从下部叶片向上部叶片以及邻近植株不断扩展。五．室内药剂测定采用药皿法和玻片萌发法对多菌灵、甲基托布津、代森锰锌、百菌清、三唑酮五种杀菌剂进行了室内筛选，测定了它们对白芷壳针孢菌丝生长和孢子萌发的抑制作用。结果表明：多菌灵对白芷壳针孢菌丝生长的抑制作用最强，但它对孢子萌发的抑制效果比较差；甲基托布津、代森锰锌、百菌清这三种药剂对病菌菌丝生长和孢子萌发的抑制作用均较好；三唑酮对白芷壳针孢菌丝生长几乎无抑制作用，但对孢子萌发的抑制效果较好。更多还原

【Abstract】 Septoria dearnessii Ellis et Everhart, the causal agent of Angelica leaf spot is the most destructive foliar disease of Radix Angelica Dahurica. The biological characteristics of the pathogen was studied first and systematically. The results are as follows:1. The biological characteristics of the Septoria dearnessiiThe temperature rage for mycelium growth and sporulation was 10 to 35℃, the optimum temperature at 25℃, the most suitable pH value was 5-7, the pathogen could grow and sporulate well on PDA, the optimum carbon sources was sucrose and the most suitable nitrogen sources was ammonium nitrogen. The light treatment hadn’t remarkable effect on the mycelium growth and sprulation. Conidia were able to germinate in sterile deionized water but at a low percentage, sugar and host juice stimulated conidial germination of the pathogen. Conidia germinated at. 10 to 35℃, with optimum temperature between 25 and 28℃. The lowestl relative humidity of germination was 93%, and the maximum rate of spore germination was in water. The optimum pH value for sporulation was pH5-7. In suitable condition, germination of conidia started within 8 hours and the percentage of germination reached above 90% at 24 hour. The light hadn’t substantial effect on spore germination. The lethal temperature of conidia was 50℃(10min).2. The infection process of Septoria dearnessiiInfection process to Angelica dahurica by Septoria dearnessii was studied. Results showed that conidia germinated at the leaves surface, then formed the branched hypha, hypha was the infection structure of S. dearnessii. The pathogen was able to penetrate host through two paths such as stomata and epidermis after inoculation. The direct penetration into epidermis was considered as a major way. The appressorium was not formed before the penetration of the pathogen. After the mycelium penetrated leaf cells, they could continue through the various cells. The cells that were infected by the pathogen could became empty, ultimately lead to the cells death.3. The infection conditions of Septoria dearnessiiThe infection of Angelica dahurica by Septoria dearnessii could be occured at 10 to 30℃, the incubation period was the shortest(12d) and the optimum temperature of infection was 25 to 30℃. The wetness period rage for infecting leaf of Angelica dahurica by Septoria dearnessii was 12-48 hour, the optimum wetness period was 24-48 hour. The Septoria dearnessii infected the basal leaves firstly, the spreaded to the upper leaves. Old leaves had more conducive to the infection.4. The infection sources and diesease dynamics of Angelica leaf spot in fieldUnder Suining in Sichuan ecological conditions, the infection sources of Angelica leaf spot were the mycelium and conidia in pycnidia, the pathogen which on the seed plants and the disease leaves in the field infected Angelica dahurica seedlings directly without overwinter. The primary diseased plants could be observed in November, and the disease began to develop with warming. From November to February the following year, the disease developed slowly because of the temperature was low. From February to April, the development of the disease accelerated gradually with the temperature rise. The diseased blossom from April to July, and the index of disease up to the highest. The disease degree began to slow down after July, with the cessation of Angelica dahurica growth and the development of the disease stopped. While the pathogen encountered rain, the conidia were released, then transmitted with rain. The conidia of the pathogen continued to develop diseased leaves and as reinfection sources. The expansion of the disease from the lower leaves to the upper leaves and nearby plants.5. The fungicides screening in laboratoryThe five fungicides were tested in laboratory to determine the effect on the mycelical growth and germination of conidia. The results showed that carbendazim inhibited the mycelial growth, but did not inhibit the germination of conidia. Thiophanate-methyl, mancozeb and chlorothalonil were good fungicides on the inhibition of the mycelial growth and the germination of conidia. Triadimefon almost had no inhibition on the mycelial growth, while it was good to inhibit the germination of conidia.更多还原