Breeding for corn borers resistance in maize / Ahmed Abd El Kader Ahmed ElKhishen ; Suppervised Ahmed Medhat Mohamed AlNaggar , Mohamed Reda Ali Shabana , Hamdy Youssef ElSherbiny

Thesis (PH.D.) - Cairo University - Faculty Of Agriculture - Department Of Agronomy

The main objective of the present investigation was to study the nature of inheritance of maize resistance to ScreticaIn 2003 season , complete diallel F1 crosses (excluding reciprocals) were made among eight inbred lines of maize that differ in their resistance to ScreticaIn 2004 season , F2 , BC1 and BC2 populations were producedIn 2005 season , three field evaluation experiments were carried out (each experiment at two locations) ; the first and second experiments were done under artificial infestation to evaluate plant reaction for maize resistance to Scretica (the first for diallel crosses and the second for six populations) and the third experiment was carried out under conditions of chemical control of the pink stem borer Scretica to evaluate the agronomic and yield traitsRCBD with 3 replicates was used for all experimentsSeed storage proteins of the eight inbreds used as parents in this study were biochemically analyzed by using SDS - PAGE techniqueData across locations showed that the F1 crosses among resistant x susceptible inbreds exhibited resistance or intermediate reactions , suggesting varying degrees of dominanceIn average , heterosis and inbreeding depression were more pronounced in the percentage of dead hearts while the intensity of damage showed the lowestMean squares due to general (GCA) and specific (SCA) combining ability for the three studied traits were highly significant , indicating that both additive and non - additive gene effects are involved in the inheritance of resistance to the pink stem borerAdditive was larger in magnitude than non - additive varianceOne gene (one group of genes) was found to control percentage of susceptible plants and intensity of damage , while two genes (2 groups of genes) controlled percentage of dead heartsNarrow - sense heritability estimates (h2n) were high for all studied resistance traitsEpistatic gene effects are generally important in the inheritance of these traits and the additive X dominance estimates are relatively the largest in magnitude as compared with other types of epistasis and are found in all studied crossesGenotypes superior in both resistance and yield traits were recommended for the future breeding programsData indicated the presence of one band at 611 kDa in all resistant inbreds which was associated with maize resistance and another one band 600 kDa in all susceptible inbreds which was associated with maize susceptibility to the pink stem borer Scretica

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