烟草品种对赤星病的抗性因素分析

选取国内外赤星病（Ａｌｔｅｒｎａｒｉａａｌｔｅｒｎａｔａ）抗感程度不同的７个烟草品种，分别在苗期和成株期对病情及抗侵入和抗扩展两个水平抗性因素进行观察。结果表明，无论在离体接种或田间发病条件下，品种间病斑数量和病斑大小都存在显著差异（Ｐ＝０．０１）。病斑数量和田间病情指数呈正相关，但病斑大小与品种抗病性无明显相关性，而它们二者的乘积和田间病情指数之间存在高度正相关，相关系数高于病历数量与病情指数的相关系数。据此可推测，各品种对赤星病的抗性机制存在不同的类型。

Analysis of Varietal Resistance-Factors to Brown spot of Tobacco

Seven tobacco varieties with various resistant or susceptible level to Alternaria alternata were chosen to investigate disease seventy and two horozontal resistance -factors, invading resistance and spreading resistance. The investigations were done on both seedlings and grown plants. The results indicated that significant variation (P=0. 01)exists among both lesion-number and lesion-size of the seven varieties under the condition of field infection as well as pluced-leaf-inoculation. Direct interrelation was found between lesion-numbers and field disease indexes while no evident interrelation exists between lesion-sizes and field disease indexes. But products of the two factors have a high level direct interrelation with field disease indexes. The interrelation coefficient r is higher than that between lesion-numbers and disease indexes. This can lead to a conclusion that different sorts of brown spot resistant mechanism may exist among the seven varieties.