Abstract: Resistance of 42 rice cultivars, imported from the United States, to the bacterial leaf blight (BLB, Xanthomonas oryzae pv. oryzae) and bacterial leaf streaks (BLS, X. oryzae pv. oryzicola) were evaluated. The results showed that 28.6%-85.7% of tested cultivars were resistant or moderately resistant to the pathotype Ⅳ and Ⅴ of BLB, and 57.2%-83.4% were resistant or moderately resistant to the strains BS39 and BS93 of BLS. IR36M4 and Gulfrose were resistant to two different diseases. Those cultivars with high resistance to BLB were also more resistant to BLS. The possible relationship between two resistance in rice cultivars were discussed.

Key words: American rice cultivars, resistance, Xanthomonas oryzae pv. oryzae, Xanthomonas oryzae pv. oryzicola

摘要： 对美国南部和西部地区广泛种植和将要推广的水稻品种42个，孕穗期接种白叶枯病和细菌性条斑病病菌，以抗病品种IR26，感病品种金刚30和南京11作为对照品种进行抗性鉴定。白叶枯病Z173和GD1358两个菌株在所有42个品种上均能侵染发病，未发现高抗或免疫品种，对Z173表现抗病或中抗水平的品种约占85％以上，表现感病的只有1个。而用GD1358接种时，表现抗病或中抗水平的品种仅占总品种数的28％左右，多数抗Z173的品种对GD1358表现中抗或中感。对GD1358表现抗病的Gulfrose, Bellmont和IR36M4三个品种对Z173也表现抗病,具有较宽的抗谱。与白叶枯病菌相仿，两个细菌性条斑病菌菌株在所有美国稻品种上均能侵染形成典型病斑，未发现高抗和免疫品种。对强毒菌株BS93表现抗病和中抗的品种分别占总品种数的19.1%和38.1%；而对中等毒力菌株BS39表现抗病和中抗的品种分别占总品种数的52.4%和31.0%，其中22个抗病品种中, 只有8个品种抗强毒菌株BS93，其余的品种对BS93均表现中抗或中感。其中Lebonnet和LA2168甚至表现感病。比较同一品种对两种不同病害的抗性表现，可以看出一些对白叶枯病有较好抗性的品种，如Gulf rose,IR36M4等对细菌性条斑病也有很好抗性，对白叶枯病表现感病的品种如Lacassine、Jasmine等对细菌性条斑病菌也呈感病反应。在测定的42个品种中未发现对白叶枯病表现抗病，而对细菌性条斑病表现感病的品种，或对细菌性条斑病表现抗病，而对白叶枯病表现感病的品种。研究结果表明，美国水稻品种对白叶枯病的抗性和其对细菌性条斑病的抗性有一定的相关性。

关键词: 美国稻, 抗性, 白叶枯病, 细菌性条斑病