【作者】 阎合；

【导师】 徐秉良；

【作者基本信息】 甘肃农业大学 ， 作物保护， 2009， 硕士

【摘要】 本文针对发生于甘肃省渭源地区的甘草叶斑病的发生情况进行了系统的调查与研究,鉴定其致病菌为豆链格孢Alternaria azukiae.对其发病规律,发病条件等进行了归纳总结。同时研究了病菌的生物学特性,在室内进行了防治甘草叶斑病的化学药剂筛选。1.本文报道了由豆链格孢(Alternaria azukiae)引起的甘草叶斑病在甘肃省渭源地区的发生。描述了该病的症状:茎,叶上形成圆形,椭圆形或不规则形的深褐色病斑,病斑表面具明显的同心轮纹,大小为2~4mm,最大可达6.0mm。发病严重时病斑连片,造成叶片干枯,茎部坏死。从甘草病株上分离得致病菌株,菌丝透明有隔膜,分生孢子梗直立或膝状,分枝或不分枝,分生孢子有的无喙,有的具柱状假喙,形状变化极大,卵形、椭圆形、倒棍棒形,表面有缢缩,淡褐色或深褐色,有横隔膜1～6个,纵隔膜0～4个。孢子大小为(18～42)um×6～15um。病叶上分生孢子梗由叶两面生,单生或簇生,分生孢子大小较PDA培养基平板上略大。与Alternaria属相关的文献资料对照,将其鉴定为Alternaria azukiae(豆链格孢)。该病原菌除可侵染甘草之外,人工接种还可侵染独活,羌活,曼陀罗以及藤三七等药用植物。2.本研究对甘草叶斑病病原菌豆链格孢(Alternaria azukiae)进行了生物学特性研究,结果表明:温度、pH对其生长和产孢都有一定的影响。该病原菌菌丝生长、产孢的最适温度为30℃,pH为8时菌丝生长最快,最易产孢。光照对病原菌菌丝生长影响不大,对产孢有一定影响。连续光照培养产孢最多,连续黑暗培养产孢最少。碳、氮源对菌丝生长和产孢量有一定的影响,甘露醇为碳源时菌丝生长最快,葡萄糖为碳源时产孢量最高。硝酸钾为氮源时最适宜菌丝生长和产孢。豆链格孢在PDA上生长较快。3.对甘草叶斑病在甘肃省渭源地区的发生规律进行了系统调查。结果表明:在田间病残体上病原菌可越冬成为田间初侵染来源,且是主要的侵染源,种子带菌次之。病害发生流行与温湿度关系密切,在温度适宜的情况下,湿度越大越有利于发病,湿度是病害发生和流行的主导因素。种植地选在高燥地区较平坦或低洼地区发病情况要轻,病情指数可降低近20。轮作可有效降低发病,间隔两年轮作相比连作甘草病情指数低近40。4.本文研究了6种杀菌剂及深绿木霉对甘草叶斑病病原菌豆链格孢的抑菌作用。结果表明所选6种杀菌剂对病原菌的生长均有抑制作用,但不同药剂之间有差异。68.75%杜邦易保水分散型颗粒具有最好的抑菌效果(EC50=8.290 ug/ml),是较为理想的杀菌剂。50%多菌灵可湿性粉剂抑菌效果不理想,几乎不能抑制病原菌豆链格孢的生长(EC50=7.14×10~3 ug/ml)。综合各种杀菌剂对豆链格孢抑菌效果来看,比克、68.75%杜邦易保水分散型颗粒、58%甲霜灵—锰锌可湿性粉剂等3种药剂都可以应用于甘草豆链格孢叶斑病的防治。深绿木霉对病菌有显著抑制作用(抑菌率73.9%),且抑菌率与木霉孢子浓度变化关系不大。更多还原

【Abstract】 It is the first report about the largely occurrence of liquorice leaf spot caused by Alternaria azukiae in the Weiyuan region of Gansu Province in China.1.The major symptoms of the disease were described in detail. It initinally appears as circular,oblong, puce lesions with concentric lines in center on leaves,the biggest lesions can reach 6.0mm. Severely these lesions gradually turn black,connect each other and eventually lead to death of very diseased sites.The pathogenetic strain was isolated from diseased leaves of liquorice. Conidiophores are straight or curved,ramification or not ramification. Conidia have a layer similar to a beak,or no beak ,they are Lacking definite form,clavate,ovate or shuttle,brown or fuscous~brown,with 1～6 transverse and 0～4 longitudinal septa. In view of the morphological characteristic,the morphology is consistence, so it is confirmed the same species. The pathogen is identified as Alternaria azukiae.Alternaria azukiae not only infect liquorice,but also infect stramonium, duhuo,tengsanqi,and other Chinese traditional medicine.2. The results of the biological characteristics of the pathogen of liquorice leaf spot showed that temperature and pH affected the mycelium growth and sporulation of the fungus. The optimum growth and sporulation temperature was 30℃.The suitable pH was 8.The light time does not affected the mucelinm growth, but affected sporulation. light condition is good to sporulate. Both carbon sources and nitrogen source had an effect on the mycelium growth and sporulation. The growth of mycelia was the quickest with mannitol , and the number of sporulation was the largest with dextrose .So did the nitrogen sources. nitre was the most suitable for the growth of mycelia and sporulation. Alternaria azukiae grew faster on PDA.3. It is the first systematic research about the ocuurence of liquorice leaf spot. The result indicated that the primary infection sources mainly come from liquorice refuse in soil, secondly from infected seeds. The occurrence of the disease is closely correlated with weather conditions, site condition and the crop rotation.4. The more effective fungicides were chosed, such as 70%thiophanate methyl,mepiquat chloride,68.75%du bang yi bao. And the 68.75%du bang yi bao has the best bacteriostatic effect in them.The bottle green Trichoderma has the more bacteriostatic effect to Alternaria azukiae, and the effect is not reduce when the spore concentration changed.更多还原