影响木麻黄青枯病抗性测定的几项因素的研究

SEVERAL FACTORS AFFECTING THE DETERMINATION OF DISEASE RESISTANCE IN CASUARINA CLONES TO PSEUDOMONAS SOLANACEARUM

木麻黄无性系对青枯假单胞杆菌的抗病性测试受到植物材料、接种条件及病级测定三方面因素的影响。研究表明在无根苗与有根苗上病害的发生具有一致性特征，并且与高度相关，但无根苗更为感病。在三种龄期的无根苗中，以木质化的褐梗最为感病，绿梗次之，嫩枝较为抗病。青枯菌在连续培养１４天后接种致病力不减。病害的相对强度在直射光、散射光及灯光等三种光照条件下无明显区别。病害强度随着接种浓度的增加而增高，但当达到一定程度后便趋缓。研究认为在室内以中等浓度的青枯菌液接种木麻黄无根褐梗苗是快速测定其抗性的一个可靠方法，并就采用相对病害强度代替发病株率作为病级指标等问题进行了讨论。

The determination of disease resistance of Casuarina clones to Pseudomonas solanacearum is subject to the variations of plant and bacterial materials, inoculation condition as well as rating method of disease seventy. It was demonstrated in this study that the infected clonal ramets and excised twigs exhibited same wilting symptom and similar disease progressing pattern; their relative disease intensities were positively correlated under the same set of inoculum densities, but the ramets were more resistant. Among three types of excised twigs,the lignified brown had highest disease rating, followed by the partially lignified green, and the tender was least susceptible.The bacteria could be consistently cultured for at least 14 days without losing its virulence.While the disease seventy of clones under sunshine,fluorescence or in shade were not significantly different, it increased as the inoculum density increased. It was suggested that using the excised brown twigs with relatively low or moderate inoculum densities inside laboratory to detect the bacterial resistance of Casuarina clones would be an efficient and reliable approach.