烟草赤星病菌致病力测定方法的研究

STUDY ON METHODS FOR IDENTIFYING PATHOGENICITY OF TOBACCO BROWN SPOT PATHOGEN

用烟草赤星病菌(Alternaria alternata)和其它植物来源的分离物(Alternaria sp.)共39个菌株分别接种烟草品种G80和G140的幼苗,并用其中24个菌株接种此二品种的离体叶片。结果表明,不同菌株对离体叶片的穿透生长能力与致病力以及对幼苗的致病力(病叶率与病情指数),明显地表现为从低到高的组群关系。其中,烟草赤星病菌5个菌株,TBA6、TBA8、TBA12、TBA19和TBA28,为表现一致的高致病力,而TBA20和TBA27表现一致的低致病力。比较发现,病菌对离体叶片的致病力(等级)与其对幼苗的致病力,在烟草赤星病菌的24个菌株间以及在两个烟草品种间的趋势相一致,而病菌对离体叶的穿透生长能力与其对幼苗的致病力之间无一致趋势。讨论认为,离体叶片法用于测定病菌的致病力不失为一种准确快速而又易于控制的方法。

The pathogenicity of 33 strains of Alternaria alternata and 6 strains or isolates from other plants to seedlings and detached leaves was tested in 2 tobacco variveties, G80 and G 140. The results indicated that the strains tested could be categorized into different groups either dependent on their ability of penetrating detached leaves and growing on them or dependent on their pathogenicity to detached leaves and seedlings. The constantly strong pathogenicity to seedlings and detached leaves was given by strains TBA6, TBA8, TBA12, TBA19 and TBA28, and constantly weak by TBA20 and TBA27. By comparision, consistent trend of pathogenicity of 24 brown spot pathogenic strains was found between inoculating seedlings and detached leaves of varieties G80 and G140 but not between penetrating-growing ability to detached leaves and pathogenicity to seedlings and detached leaves. It was suggested that the method for identifying pathogenicity by inoculating detached leaves could be accurate fast and easv to be controlled.