The pink stem borer (Sesamia nonagrioides Lef.) is the main pest of maize (Zen mays L.) in northwestern Spain. Sesamia nonagrioides prefers attacking stems rather than ears, but it can also produce direct grain injury by feeding of larvae into the ear. The objective of our work was to determine the importance of GCA, SCA, and reciprocal effects in the inheritance of ear resistance to the pink stem borer, On the other hand, correlation coefficients among ear damage ti aits were calculated for determining the traits that give a better measure of grain and cob resistance. A ten inbred-line diallel was evaluated for two years for ear resistance. Inbred parents and hybrids were tested in adjacent trials under artificial infestation conditions. In both types of trials, ear damage trails were recorded at han esl. The correlation coefficients between grain and coh damage traits were very low. General appearance of the ear had the highest correlations with the other grain damage traits. Therefore, this trait appeared as a good indicator of grain resistance to Sesamia nonagrioides attack. General combining ability was significant for all traits, while specific combining ability and reciprocal effects were significant only for the percentage of ears with damaged cob. It will be necessary to breed jointly for grain resistance and cob resistance to obtain ear resistance. Since, for this set of lines, only additive effects were significant for grain damage trails, the inbreds with favorable GCA for these trails could he used as donors of grain resistance for making a synthetic population that could be bred by a intrapopulational recurrent selection program for grain resistance. However, the breeding of cob resistance should use GCA, SCA and reciprocal effects. So, an interpopulational recurrent selection program for cob resistance could be carried out. The correlation between pa rental means and GCA estimates for each trait were not high enough to estimate the hybrid behavior from the ear resistance of the inbreds to the pink stem borer. Inbreds A661 and CM105 could be used by maize breeders as sources of ear resistance since they were good combiners for grain resistance and did not show unfavorable GCA effects for cob resistance.

Peer reviewed