水稻品种苗期阶段对白叶枯病的抗性研究

 根据水稻品种各叶期对白叶枯病的抗性表现和强弱程度可分为四类:(1)全期抗病型;(2)全期中抗型;(3)苗感成株抗病型;和(4)全期感病型。可以看出,水稻品种除少数苗感成抗型外,其余三种抗性类型苗期与成株期的抗性反应是一致的。由于中抗、成抗和感病品种各叶期的抗性有随着叶位的升高而抗性增强的趋势,不同抗性品种在苗期阶段抗感对比均较成株期明显。因此,水稻品种对白叶枯病的抗性鉴定采用苗期鉴定方法是可行的。影响水稻品种苗期抗性的因素是:苗龄(叶期)、观察时期、品种与菌株的组合等。

STUDIES ON THE RESISTENCE OF SELECTED GERMPLASM MATERIALS TO THE RACES OF XANTHOMONAS CAMPESTRIS PV. ORYZAE IN THE PHILIPPINES AT SEEDLING STAGE

According to the resistance to bacterial blight Xanthomonas campestris pv. oryzae expressed at different growth stage of rice plant, four types of resistance/susceptibility have been recognized:i. e., (R), overall moderate resistance (MR), adult resistance (AR) and overall susceptibility (S). The type of reactions expressed at the seedling stage is coincident with that in adult stage except for a few varieties having the adult resistance. The degree of resistance has been found to increase with growth stage in all susceptible or moderate types of resistance. Therefore, the resistance/susceptibility in the varieties of different resistance can be more clearly observed at the seedling stage than at adult stage. Evaluation of resistance of rice varieties to the bacterial blight at the seedling stage may be taken. The reaction of varieties at seedling stage are affected by the factors as following:the seedling age, the time of observation. some particular variety-isolate combination, etc.