Combining Ability of Transitional Highland Maize Inbred Lines

Information on the combining ability of highland maize (Zea mays L.) germplasm is of great value for future hybrid development programs. Such a study has been poorly exploited in the highland areas of Ethiopia, due to limited research efforts in previous years. This study was conducted to determine the combining ability of highland maize inbred lines. The crosses were made from five lines and three testers using line by tester. The resulting crosses and their parents were evaluated at Kulumsa and Ambo in 2003, following recommended cultural practices. The combined analysis of variance showed that the mean squares due to genotypes were significant for all traits, except for thousand kernel weight and shelling percentage. B.T.Z.T.R.L.137-B-2-1-B X 142-1-e followed by B.T.Z.T.R.L-71-B-3-3-B X 142-1-e and B.T.Z.T.V.C-283-B-1-1-B X 144-7-b were the three top-yielding crosses. B.T.Z.T.V.C-283-B-1-1-B and B.T.Z.T.V.C-43-B-2-2-B manifested a high positive SCA effect with F-7215, implying these two lines combine well with F-7215. B.T.Z.T.R.L.137-B-2-1-B manifested negative SCA with F-7215, indicating that they could have a similar genetic background. The mean squares due to GCA of lines, testers and SCA of crosses were significant for ear height, ear length and grain yield B.T.Z.T.R.L.137-B-2-1- B and 142-1-e had high GCA for grain yield. The maximum SCA effect for grain yield was obtained from B.T.Z.T.R.L.137-B-2-1-B X 142-1-e and B.T.Z.T.R.L-71-B-3-3-B X 142-1-e. Generally, the magnitude of mean squares due to GCA of lines was higher than that of the SCA in most of the cases, indicating that additive gene actions were more important than non-additive with regard to inheritance of the traits studied. Keywords: Combining Ability; Gene Action; Heterotic Pattern; Zea maysEast African Journal of Sciences Vol. 2 (1) 2008: pp. 19-2