Components and genetics of resistance to Peronosclerospora philippinensis (Weston) Shaw causing Philippine downy mildew in corn
1990
Capio, E.R.
Components of resistance to the Philippine downy mildew were studied using nine advanced corn population during the dry season of 1988 at the UPLB [Philippines Univ., Los Banos, College, Laguna, Philippines]. Of the five components evaluated, average onset of system symptom, colonization, percent systemic infection and apparent rate of infection were significantly related to disease resistance. Sporulation as a component was found not related to resistance. Correlation among the components suggests that reduction in disease severity is achieved by retarding the rate of disease progress rather than delaying its onset. The study on the genetics of resistance involving sets of S1's derived from three selected populations using generation mean analysis, combining ability analysis, and Hayman's model revealed that additive gene effects predominantly influenced the inheritance of resistance to P. philippinensis. In some crosses, dominance and epistatic effects were also observed. These findings in addition to those reported by other workers should be considered in breeding for resistance to downy mildew in corn.
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