COMBINING ABILITY FOR SOME YELLOW MAIZE INBRED LINES BY DIALLEL CROSSES

Abstract

Eight yellow maize inbred lines (L 730, L 731, L 739, L 743, L 744, L 745, L 746 and L 749) were planted at Gemmeiza Research Station, and were crossed in a diallel cross system during the growing season 2009. The 28 crosses and two check hybrids (SC 162 and SC 166) were evaluated at Gemmeiza and Sids Agricultural Research Stations during 2010 growing season. Data were collected on number of days to 50% silking (day), plant and ear heights (cm), resistance to late wilt disease and grain yield ( ton/ha) and analyzed according to Griffing (1956) method-4 model-1fixed modelfor each location and their combined performance. Locations mean squares were significant for all studied traits, except for number of days to 50% silking. Variations of genotypes (G) and their partitions; crosses (Cr), checks (Ch) and Cr vs Ch were significant for most traits, except some partitions for all the studied traits under the two locations and their combined performance, as well as their interactions with locations were significant for mean squares of most partitions. These results indicated that the genotypes and their different partitions differed in their performances from location to another for all the studied traits. GCA and SCA mean squares for each location and their combined were significant for all the studied traits, except for plant height and SCA for ear height under Gemmeiza and resistance to late wilt disease under the two locations and their combined performance. Moreover, interactions GCA and SCA with locations were significant for all the studied traits, except for resistance to late wilt disease under the combined performance only, indicating that additive and non-additive effects were important in the inheritance of the studied traits. On the other hand, the ratio of δ2 GCA / δ2 SCA was greater than unity for most studied traits, indicating an importance of additive gene effects in the inheritance of studied traits. While, the ratio δ2GCA x loc/δ2SCA x loc indicated an important both additive and non-additive effects in the expression of these studied traits, Moreover, the additive and non-additive effects were more interacted by environmental conditions ( locations) under this study . The inbred line L 743 seemed to be a good combiner for earliness, inbred line L 749 was the best combiner for shorter plants and lower ear placement, inbred line L 730 exhibited desirable GCA effects for resistance to late wilt and grain yield, also the inbred line L739 gave positive and desirable GCA effects for grain yield (ton/ha). Three crosses i.e. 1x8, 1x4 and 3x5 (10.21, 10.11 and 9.91 ton/ha) significantly out-yielded the check hybrid SC162 9.12 ton/ha by (11.95, 10.90 and 8.70 %, respectively). These crosses are considered promising comparing with the check hybrid SC162 under this study.