烟草赤星病菌株毒力与繁殖代数的关系

为明确烟草赤星病菌的毒力与其繁殖代数的关系,在室内采用离体、室外采用活体两种接种鉴定方法分别测定了烟草不同生长阶段分离到的6个赤星病菌株的毒力,并采用聚类分析方法比较了各菌株的毒力差异。结果表明,赤星病菌在田间繁殖代数与其毒力大小有关,生长后期分离的菌株(4、5和6号)比生长前期分离的菌株(1、2和3号)毒力强,即赤星病菌在田间繁殖代数越高,毒力越强。毒力分析聚类树状图也显示了菌株间的毒力差异,根据供试菌株在3个烟草品种上的毒力反应,可将其分为2个组,生长前期分离的菌株为一组,生长后期分离的菌株为一组。

Relationship between Isolate Virulence and Reproductive Order of Generation of Alternaria alternata Keissler

In order to study the relationship between the isolate virulence and reproductive order of generation of(Alternaria alternata) Keissler,the outdoor inoculation tests in vivo and indoor tests in vitro were conducted to determine the virulence of six isolates of A.alternata from different growing stages of tobacco plants,and the virulence differences were compared with cluster analysis.The results showed that the virulence differences of the isolates were significant,the virulences of isolates No.4,5 and 6 from late growing stage were stronger than those of isolates No.1,2,and 3 from early stage,namely,the virulence of the virus becomes stronger generation after generation.The cluster dendrogram of virulence analysis gave the same results.The isolates could be divided into two groups based on their virulence reactions on three tobacco cultivars: one was isolated from early growing stage and another was from late stage.