【作者】 李卫华；

【导师】 李健强；

【作者基本信息】 中国农业大学 ， 植物病理学， 2005， 硕士

【摘要】 通过直接观察、解剖培养和显微观察、定量四唑染色（TTCH）、高效液相色谱（HPLC）、环境扫描电镜-X射线能谱分析方法（ESEM-EDAX）、隔离种植、毒力测定、种子处理效果检测等方法,研究了紫斑病菌在大豆种子上的寄藏部位、紫斑病对大豆种子的影响、大豆种子传病行为以及药剂对病菌的抑制作用及处理种子的防治效果等问题,获得以下几方面的结果: 1、紫斑病菌主要存在于大豆种子外表皮与中层之间,大豆胚中未能检测到病原菌的存在。 2、随着种子受害程度的增加,种子活力逐渐降低,有活力种子百分率和吸光值之间存在正相关关系,回归方程为Y=0.0101X+0.9812,相关系数为0.9294。HPLC方法在受害大豆表皮中检测到尾孢毒素,而在胚中未检测到该毒素的存在;受害种子表皮中毒素的含量随着受害级别的增加而迅速提高,3级和4级大豆紫斑粒表皮中毒素含量丰富,分别达到65和294μg/mg大豆表皮。通过ESEM-EDAX方法在供试大豆中共检测到10种元素,大豆种子受害后元素种类减少,在大豆种皮受害部位的化学元素为C、O、K、Ca,胚中受害部位为C、O、K、Mg,其他元素的质量百分含量降至检测水平以下;与健康种子相比,受害大豆中C、K元素含量降低,O元素含量增加。初步结论:大豆感染紫斑病后,种子活力和单位大豆表皮中的尾孢毒素含量随着种子受害程度的增加而分别降低和提高;种子受害后化学元素元素种类和含量改变。 3、田间跟踪观测大豆紫斑病通过种子传播的行为结果表明,按照1:4比例播种病、健种子混合样本,发芽势和出苗率分别为64.50%和91.25%,与健康种子对照无明显影响;病、健混合样本获得的植株子叶、幼根、茎、叶片、豆荚在发育过程中均能观察到典型的发病症状,在部分显症组织中检测到紫斑病菌的存在;病、健混合样本收获后的子粒中紫斑病粒率与播种时相比增加了169%,达到54.8%,明显高于健康种子样本收获的病粒率;收获发病植株后的土壤中监测到大豆紫斑病病原菌的存在,达到21.6%,明显高于健康对照样本。证实种子带菌是大豆紫斑病的初侵染来源,该病可以通过种子传播,造成土壤带菌。 4、从7种杀菌剂中筛选到4种可以应用于种子处理,它们是多菌灵、福美双、咪鲜胺、恶霉灵,其EC₅₀分别为0.0612、8.6284、11.4859、13.6347μg/ml;100kg大豆种子适宜的施用药剂量的范围分别是100-500、250-500、280-350、100-2000g有效成分。在此范围内,进行种子处理的消毒效果显著,对种子安全,并且对大豆的发芽出苗具有一定的促进作用。更多还原

【Abstract】 By means of dry detection, microscopy, TTCH, HPLC, ESEM-EDAX, segregated-planting and several agrochemical testing, this study researched the location of pathogen in soybean seed, the effect of the pathogen to soybean seed and the seed-transmitted action, and screened several fungicides to control the disease through seed treating.1. Cercospora kikuchii could be detected on and in the surface of soybean seed, especially between the epidermis and middle, but not in embryo.2. With the level of seed-infected increased, the vigor of soybean seed decreased obviously, and percentage of vigorous soybean seeds was positively correlated with the OD of TTCH in linear relationship of Y=0.010IX + 0.9812, and the corresponding coefficients of determination was 0.9294. Data of HPLC indicate that cercosporin was not extreated from embryo but coat of soybean seed, and with the level of seed-infected increased, cercosporin’s content also grew rapidily to 65 and 294μg in each each gram seed coat of soybean in level 3 and 4 respectivly. 10 kind of chemical elements were detected by ESEM-EDAX from tested seeds, but only C, O, K, Ca was found in the infected site on soybean surface, and C, O, K, Mg in that of embryo; the Wt% and At% of another chemical elements decreased below the zero line in test; the content of C, K in infected seed decreased, and O increased compared with healthy soybean seed. Conclued that with the level of seed-infected grow, the content of cercosopoin increased and seed vigor of infected soybean by pathogen decreased; and after infected, the content and variety of chemical elements of soybean seed changed.3. Results about the ransmittion conducut of cercospora kikuchii from seed to plant and new seed indicated that germination energy and germination rate of the combination seeds are 64.50% and 91.25%, respectively. During the grow life of combination soybean seeds, the typical affected symptom were observed on cotyledon, radicel, stem, leaf, pod and seed. And pathogen was tested in some affected tissues. The percentage of diseased seed after harvest is 54.8%, as 169% as control’s, and the pathogen in the soil was tested from where the diseased plant was harvested., moreover, percentage of pathogen tested in soil is 21.6%, higher obviously than control., concluded that the disease may be transmitted by seed.4. Carbendazim, prochloraz, bymexazol, and thiram were screened from 7 tested fungicides to be used in seed treating, their EC50 is 0.0612、8.6284、11.4859、13.6347μg/ml, When each 100kg soybean seed was treated, 100-500,250-500,280-350,100-2000g effected ingredient of the four fungicides respectively was needed, which made their control effect is good and safty to seedling germination and growing.更多还原