稻紋枯病病原菌菌核之病原性

Abstract

本試驗係檢討稻紋枯病菌菌核切開小塊時之病原性是否有差異及該菌核之侵害持續時間，其結果如下︰ 稻紋枯病菌菌核曾切開成為 ， ， 及 後其病原性和無切開菌核之差異不大，均維持強度的病原性。但其病斑大小愈切開呈小塊其病斑愈小。供試抽穗期的水稻，接種各葉鞘時，自上向下第2葉鞘的感病程度（病斑數，病斑長）最高，其次為劍葉，再其次為第3葉鞘。 同一菌核接種於孕穗期的稻葉鞘，經過4天形成病斑後，將該菌核取下再接種於另支葉鞘，如此連續接種者每次都可減低侵害能力，至第5次就全部失卻病原性。另如每次取下菌核並經陰乾後再接種時，其侵害能力僅維持3次。

In this experiment the pathogenicity of the cutted scierotia of rice sheath blight fungus and the invading ability continued period of the scierotia were reported. The results could be summarized as follow: 1. Comparing the pathogenicity of the sclerotia cutted in to 1/2, 1/4, 1/8, 1/16 pieces with the whole ones, the difference was not significant, the pathogenicity were all kept. But the size of the lesions were different, the smaller the sclerotium cutted in to, the smaller the lesion was presented. While during the booting stage, inoculation was made on every sheath of rice plant. The susceptible degree (number and length of the lesion) was highest on second sheath counted from the upper part of the rice plant, the next susceptible sheath belong to flag leaf and the third one was on third sheath. 2. Inoculating the same sclerotium on rice sheath during booting stage. After four days the lesions were formed, then took the sclerotium and transfer to another sheath. The pathogenicity was lost on the fifth time, every time the invading ability of the sclerotium decreased. While the sclerotium was put under room temperature for drying for one night before the next time transfer, the invading ability could only continued for three times.