烟草种质资源苗期黑胫病抗性鉴定研究

对50份烟草种质资源进行苗期黑胫病抗性鉴定，研究发现共有抗病品种13份，中抗品种25份，中感品种10份，感病品种10份。三次病指差值小于10的品种有24份，占参试品种的48％，其中抗病品种13份，中抗品种8份，中感品种2份，感病品种1份。三次病指差值大于10的有9份，占参试品种的18％，均为中抗（6份）、中感（3份）品种。结果表明，接种病菌5d内抗病和感病品种均可充分表现出抗性或染病性状，从而作出鉴定，而中抗品种和中感品种在接种后5～10d的病情发展变化比较快。

Studies on Identification of Resistance to Black Shank Disease of |Tobacco Germplasm Resources in Seedling Stage

Resistance of 50 tobacco varieties to black shank in seedling stage was evaluated in this study. Among these varieties, 13 were resistant, 25 were moderate resistant, 10 were medium susceptible and 10 were susceptible. There were 24 varieties （48% of the total screened varieties） with less than 10 differences in value of three times resistance index. Among them, 13 were resistant, 8 were moderate resistant, 2 were moderately susceptible, and 1 was susceptible. There were 9 varieties with over 10 differences in value of three times resistance index which accounted for 18% of the total screened varieties. All of them had moderate resistance （6 varieties） or moderate susceptible （3 varieties） to black shank. These results showed that the resisttant or susceptible varieties were sensitive and could be identified within 5d of inoculation, and the disease occurred on seedlings of moderate resistance and moderate sensitive varieties could progress very quickly after 5d to 10d of inoculation.