茄青枯病菌发病烟株根际土壤营养状况分析

为探究烟株根际土壤营养状况与青枯病发生的关系，摸清影响烟草青枯病发生最关键的土壤养分因子，以从重庆市烟草青枯病发生十分典型的黔江植烟区采集的177份根际土壤样品为供试材料，测定并采用t检验、因子分析、判别分析等方法分析了土壤pH、有机质、碱解氮、速效磷、速效钾、交换性钙和镁、有效铁、有效锰、有效铜、有效锌、有效硼、有效钼13项指标。结果表明:土壤pH、有机质、速效钾、交换性钙、有效硼、有效钼含量偏低以及土壤碱解氮、交换性镁、有效锰含量偏高均有可能降低土壤的抑病效果，导致青枯病严重发生；烟草青枯病发病烟株根际土壤的钙镁比(4.04)明显低于健康烟株根际土壤的钙镁比(9.86)；因子分析结果显示，土壤中低水平的有效钼、交换性钙可能是导致青枯病发生流行最主要的因子；通过判别分析可知，烟株根际土壤中速效钾、交换性钙、有效钼、有机质、有效硼5个成分的含量情况可能是判别青枯病发病与否的关键因子，同时也构建了相应的判别函数。 

Nutritional status analysis of rhizosphere soil around bacterial wilt disease tobacco

In order to explore the relationship between the nutritional status of tobacco rhizosphere soil and bacterial wilt, and find out the crucial soil nutrition factors which are closely related to bacterial wilt, we regarded 177 soil samples as experimental materials, which came from Qianjiang in Chongqing. By the method of t-test, factor analysis and discriminant analysis, we got the following results. To begin with, when there were low levels of soil pH, organic matter, rapidly available potassium, convertible calcium, available boron and molybdenum, and high concentration of convertible magnesium and available manganese, tobacco bacterial wilt would result in serious losses to tobacco, and rapidly spread. Secondly, the Ca/Mg value (4.04) of rhizosphere soil around bacterial wilt disease tobacco was significantly lower than the heath’s (9.86). Additionally, by the factor analysis, we concluded that low level of available molybdenum and exchangeable calcium, in tobacco-growing soil, were the overriding factors of bacterial wilt’s occurrence and epidemic. Besides, by using discriminant analysis, we found that they, rapidly available potassium, convertible calcium, active molybdenum, organic matter and available boron in tobacco rhizosphere soil, might be the key factors for whether the tobacco-cropping soil was health or not. Furthermore, we also constructed two discriminant functions.