烟草立枯病菌侵染特性研究

Infection characteristics of Rhizoctonia solani isolated from tabacco

对烟草立枯病菌的侵染方式及部位、侵染时期、侵染条件和交互致病性等方面进行测定,结果表明,伤口有利于烟草立枯病菌的侵染;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,烟草立枯病菌可侵染水稻和玉米,同时玉米纹枯病菌和水稻纹枯病菌也可引起烟草发病。

This paper studied the infection methods and parts,infection period,infection conditions and interactive pathogenicity of Rhizoctonia solani isolated from tabacco. The results showed that wound was beneficial for the infection of R.solani. The tobacco leaf,leaf vein,each part of stem and roots could be infected by the pathogen. Pathogeninfecting favorable stage of tobacco plant was seedling stage,and the disease rate under non-wound inoculation condition reduced significantly with the the growth of tobacco plant. At 25℃-30℃,the pathogen infection was strong,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 increase. The results of modified selective medium testing showed that the higher the amount of soil pathogens had,the severer the disease occured. 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 occurrence of tobacco damping-off.