INHERITANCE OF RESISTANCE IN MAIZE TO THE SPOTTED STEM-BORER, CHILO-PARTELLUS (SWINHOE)

Inheritance pattern in maize (Zea mays L.) for resistance to the spotted stem-borer Chilo partellus (Swinhoe) was investigated in a diallel analysis involving six, three resistant and three susceptible maize inbreds. Resistance to both leaf feeding and stem-tunnelling was predominantly additive. Non-additive gene action was also important for stem-tunnelling. Deadheart and tolerance appeared not to be controlled by either type of gene action. Significant positive inbreeding depression was observed in nearly all instances for leaf feeding deadheart and stem-tunnelling. But for tolerance, most of the significant inbreeding depressions observed were negative. Heterotic effects were negative and significant in most cases, but positive for tolerance in situations where the inbreeding were negative. However, non-significant F1 vs F2 and Inbred vs Hybrid for tolerance is an indication of the general lack of inbreeding and heterosis respectively, for the trait. High narrow-sense heritability estimate observed for leaf feeding suggests that selection within F2 families will be effective, while frequency distribution of leaf feeding ratings among F2 populations of resistant x susceptible crosses indicate susceptibility to be partially dominant. Correlations among the resistant parameters revealed some form of association that need further investigation. It is concluded that resistance to C. partellus in maize is quantitative and can thus be modified by appropriate breeding procedures.