【作者】 李悦；

【导师】 袁高庆；

【作者基本信息】 广西大学 ， 植物病理学， 2016， 硕士

【摘要】 据2010年至2013年的广西烟草有害生物普查发现,由立枯丝核菌(Rhizosonia solaani Kuhn)引起的烟草立枯病已成为广西各烟区大田期烟株上普遍发生的病害。本研究对广西烟草立枯病进行田间系统调查并初步建立病情指数与影响因子的回归模型;对烟草立枯病菌LC11-6(AG4HG-I)的侵染特性进行了探究;测定了 4种药剂对烟草立枯病的防治效果,研究结果如下:广西靖西县烟草立枯病田间系统调查的结果显示,该病在团棵期开始出现,盛发期为采收期,发病率为12.87%,病情指数为5.69;利用SAS软件对病害发生的严重度与气象因子和土壤菌量的关系进行逐步回归分析,从7个变量中筛选出对病情指数(y)影响效果最显著的两个变量X4(周平均相对湿度)和x7(周平均土壤菌源量),构建回归模型 y=0.02018x4+0.03945x7—1.0054,R2=0.994;通过残差分析和预测值与实测值对比可知所建模型合理,拟合情况良好。伤口有利于烟草立枯病菌LC11-6的侵染;病菌可侵染烟株的叶肉、叶脉、茎部(上中下)及根部等多个部位导致发病;烟株易被侵染的生育期为苗期,随着烟株的生长发育,无伤接种的发病率明显降低;25℃～30℃为病原菌侵染的适宜温度,15℃时病原菌不能侵染烟株;当土壤含水量在47.83%～76.41%范围内时,随着土壤含水量的降低,病情指数随之增高;利用改良的选择性培养基测定显示,土壤含菌量越高病情越重;交互致病性测定结果表明,LC11-6可侵染水稻和玉米,同时玉米纹枯病菌XD1406和水稻纹枯病菌XD0906也可引起烟草发病;14个烟草品种对立枯病的抗病性鉴定结果显示,云烟97、红花大金元和MS云烟87属于高抗品种,云烟203和安烟2号属于高感品种。嘧菌酯、苯醚甲环唑、井冈霉素和代森锰锌对烟草立枯病的盆栽药效试验结果显示,25%嘧菌酯悬浮剂有效成分为0.21g/L的防效最好,为79.36%;40%苯醚甲环唑悬浮剂有效成分为0.11g/L的防效最差,仅为46.44%。选用嘧菌酯对不同发病级别的病株进行防治,若病株发病级别是1级和3级,防治效果明显,当病株发病级别达到5级及以上,防治效果显著下降。更多还原

【Abstract】 According to the pest survey of tobacco from 2010 to 2013 in Guangxi,tabacco damping-off caused by Rhizoctonia solani Kuhn is a common disease at field growth stages of tobacco.In this dissertation,the field systematic investigate on tobacco damping-off was made,and the regression model was developed by analyzing the disease index and its impact factors,The infection characteristical of the pathogens(strain LC11-6,AG4 HG-I)and its pathogenicity to tobacco cultivars were also investigated.Meanwhile,the control efficacies of 4 fungicides on the disease were tested.The main results are as follows.According to the field systematic investigate of tabacco damping-off in Jingxi county,the disease began to appear at the resettling stage and the high incidence at the harvest stage,with incidence rate 12.87%.By using SAS software,the regression model of disease index and impact factors was established,which was y=0.02018 x4+ 0.03945 x 7—1.0054,R2=0.994.x4 is weekly average relative humidity and x7 is weekly average amount of soil pathogens.Wound was beneficial for the infection of R.solani LC11-6.The tobacco leaf,leaf vein,stem and root could be infected by the pathogen.Pathogen-infecting favorable stage of tobacco was at seedling stage,and the disease rate under non-wound inoculation condition reduced significantly with the growth of tobacco plant.The range of 25 ℃ to 30 ℃ was the optimum temperature for the pathogen infection,and the pathogen could not infect tobacco under 15 ℃.With the decrease of soil moisture in the range of 47.83%- 76.41%,the disease index would be increased.The results of modified selective medium testing showed that the higher the amount of soil pathogens had,the severer the disease occurred.Interactive pathogenicity test indicated that R.solani isolated from tabacco could infect rice and corn,and R.solani isolated from rice and corn also could cause the tobacco damping-off.The 14 tobacco cultivars had different resistance to R.solani LC11-6.Yunyan97,Honghuadajingyuan and Yunyan 87 belonged to resistant cultivars,but Yunyan 203 and Anyan No.2 belonged to susceptible ones.The control efficacies of azoxystrobin,difenoconazole,validamycin and mancozeb on tabacco damping-off in pot trials were 79.36%,46.66%,69.04%,68.34%respectively.When the disease rank was at 1 to 3,azoxystrobin could significantly control the disease,but not effectively if the disease developed to the rank of 5 and above.更多还原