Combining Ability in Maize Lines for Agronomic Traits and Resistance to Weevil (<i>Sithophilus zeamais</i> Motschulky)

Abstract

In Ethiopia, heavy losses to stored maize are inflicted by various insect pests including Sitophilus weevils and Sitotroga cereallela. This study was  conducted to determine the combining ability of five introduced inbred lines in agronomic traits and maize weevil resistance by crossing them with three  testers using line × tester mating system. These crosses were then evaluated in tri-plicated randomized complete blocks at Bako Agricultural Research  Center in 2003. Samples (50 g) of the F₂ full-sib grain of the genotypes were further tested for weevil resistance under a no-choice laboratory  environment. Mean squares due to general (GCA) and specific (SCA) combining ability were significant for most of the agronomic traits. However, GCA  mean squares predominated in all weevil resistance traits. The lines varied in their GCA effects for the various agronomic traits considered. However, all of  them were found to be poor general combiners for grain yield, although certain crosses gave acceptable yield. The lines SZSYNA99-F₂-133-2-3,  SZSYNA99-F₂-33-4-1, SZSYNA99-F₂-33-4-2 and SZSYNB99-F₂-98-4-3 exhibited desirable GCA effects for most of the resistance traits. Overall, this study  suggested the existence of heritable weevil resistance quantitative traits that can be used in weevil resistance breeding programs.