【作者】 秦鹏；

【导师】 叶华智；

【作者基本信息】 四川农业大学 ， 植物病理学， 2009， 硕士

【摘要】 玄参作为一种重要的中药材其在中医上的应用相当广泛,四川大规模种植的川玄参是川产地道药材,而玄参斑枯病是危害玄参的首要病害,引起此病害的病原菌为玄参壳针孢(Septoria scrophulariae West.)。本文首次较系统地研究了玄参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和室内药剂筛选,研究结果如下:一.玄参壳针孢(S.scrophulariae)生物学特性玄参壳针孢菌丝生长和产孢的温度范围是10—30℃,最适温度范围为20—25℃;最适pH为6—7;最适培养基为10%汁液+PDA培养基;菌丝生长以可溶性淀粉和麦芽糖最好,病菌产孢量以蔗糖和麦芽糖最大;对氮源的利用以有机氨态氮最好;光照条件对病菌生长和产孢无明显影响。病菌孢子萌发的温度范围为10—35℃,最适温度为20—25℃;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,病菌孢子在20%汁液中萌发率最高;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:pH5—7适合分生孢子萌发;光照条件对分生孢子萌发无显著影响。分生孢子致死温度为55℃(10min)。二.玄参壳针孢(S.scrophulariae)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玄参的过程。结果表明:玄参壳针孢(S.scrophulariae)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.玄参壳针孢(S.scrophulariae)侵染条件在10—30℃的温度条件下玄参壳针孢能成功侵染玄参,最适发病温度为25℃,此时潜育期最短,为9d,病斑数量最多,病情发展最快;保湿时间范围在12—72h时,植株均能发病,最佳保湿时间为24—72h,其潜育期最短,保湿72h发病最严重;玄参老叶比新叶更容易感病。四.玄参斑枯病侵染源及田间动态病菌以分生孢子器的形式在土壤和病残体中越冬,次年春季遇雨水分生孢子器释放出分生孢子引起初侵染。3月上、中旬在个别植株下部叶片有极零星病斑的出现,此时病株率和病叶率很低,分别为5%和6.06%;3—5月病害从下部叶片向上部叶片以及邻近植株发展,随气温上升和雨水增多,病株率、病叶率和病情指数明显升高,分别为38%、32.29%和26.11;7—10月玄参地上部分生长速度变慢新增叶片数少,高温、高湿的气候条件使病情发展得很快,病株率、病叶率和病情指数迅速上升,分别为100%、79.89%和62.07。五.室内药剂测定室内药剂测定采用药皿法和玻片萌发法,测定了甲基托布津、多菌灵、代森锰锌、百菌清和三唑酮这5种药剂对病菌菌丝生长和孢子萌发的抑制作用。试验结果表明:甲基托布津、多菌灵、代森锰锌、百菌清4种药剂对菌丝生长和孢子萌发抑制作用均较好,三唑酮对菌丝生长和孢子萌发抑制效果较差。更多还原

【Abstract】 Scrophulariae grayana as an important traditional herbal, its has a wide range of applications in traditional Chinese medicine, the current production has a large-scale cultivation. Septoria scrophulariae West, the causal agent of Figwort leaf spot is the most destructive foliar disease of Figwort Root. The biological characteristics of the pathogen was studied first and systematically. The results are as follows:1. The biological characteristics of the Septoria scrophulariaeThe temperature rage for mycelium growth and sporulation was 10 to 30℃, the optimum temperature was 20 to 25℃, the most suitable pH value was 6 to 7, the pathogen could grow and sporulate well on 10% of the host juice + PDA, soluble starch and maltose are the most favorable to mycelial growth, sucrose and maltose are the most conducive to sporulation, organic nitrogen is more conducive than the inorganic nitrogen to mycelium growth and sporulation. The light treatment hadn’t remarkable effect on the mycelium growth and sprulation. Conidia germinated at 10 to 35℃,with optimum temperature was 20 to 25℃. Conidia were able to germinate in sterile deionized water but at a low percentage, sugar and host juice stimulated conidial germination of the pathogen. The maximum rate of spore germination was in 20 % of the host juice. The lowest relative humidity of germination was 93 % ,and the maximum rate of spore germination was in water. The optimum pH value for sporulation was 5-7. The light hadn’t substantial effect on spore germination. The lethal temperature of conidia was 55℃(10min).2. The infection process of Septoria scrophulariaeInfection process to Scrophulariae grayana by Septoria scrophulariae was studied. Results showed that conidia germinated at the leaves surface after inoculating for six hours, conidia germ tube from the one side, on two sides or the middle, tube extended,then formed the non-branched hypha, hypha was the infection structure of S. scrophulariae. The pathogen was able to penetrate host through two paths such as stomata and epidermis after inoculation.3. The infection conditions of Septoria scrophulariaeThe infection of Scrophulariae grayana by Septoria scrophulariae could be occured at 10 to30℃, the incubation period was the shortest(9d) and the optimum temperature of infection was 25℃. The wetness period rage for infecting leaf of Scrophulariae grayana by Septoria scrophulariae was 12-72 hour, the optimum wetness period was 24-72 hour. The Septoria scrophulariae 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 Scrophulariae leaf spot in fieldThe infection sources of Scrophulariae leaf spot were the mycelium and conidia in pycnidia, the pathogen overwinter on the disease leaves and in the field in form of the mycelium. The following year in spring, the pathogen encountered rain, the conidia were released, then caused primary infection. The diseased began to appear in early March, the strain rate and the diseased leaves rate were 5 % and 6.06 %. From March to May the expansion of the disease from the lower leaves to the upper leaves and nearby plants. Because of the temperature riseing fast and rainwater is more, the strain rate, the diseased leaves rate and the index of disease increased significantly. The strain rate, the diseased leaves rate and the index of disease were 38%,32.29% and 26.11. From July to October, the Scrophulariae ground part growth is slowing, the new leaves is less, the disease developed rapidly because of the hot and humid weather conditions, so the strain rate, the diseased leaves rate and the index of disease reached to 100%、79.89% and 62.07.5. 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 Thiophanate-methyl, carbendazim, mancozeb and chlorothalonil were good fungicides on the inhibition of the mycelial growth and the germination of conidia. Triadimefon were bad fungicides on the inhibition of the mycelial growth and the germination of conidia.更多还原