ESTIMATION OF GENERAL AND SPECIFIC COMBINING ABILITY IN F1 HYBRIDS FOR GRAIN YIELD AND ITS COMPONENTS IN GRAIN SORGHUM [SORGHUM BICOLOR (L.) MOENCH].

Ten exotic cytoplasmic male sterile lines (C.M.S.) and two restorer lines viz local 162 as tall variety and NES 2412 as a shorts dual purpose variety were grown at Al-Azhar Univ. Assiut Exp. Farm in 1998 season.  The ten C.M.S. lines were top crossed with the two restorer to develop 20 top crosses [ten with local 162 and ten with NES 2412].  These top crosses with the two restorer lines and the two check varieties [Giza 15 and Dorado] were evaluated in completely randomized block design with 4 replications in two locations at Assiut and Sohag Governorates in 1999 season.  The characters studied included i.e., plant height, days to 50% blooming, panicle width, panicle length, 1000-grain weight and grain yield.  Analysis of variance detected highly significant differences among genotypes for all studied traits.  Generally, the 20 F₁ hybrids involving NES 2412 and Local 162 showed wide range of heterosis with negative and positive values of the studied traits.
                Estimates of variance components revealed that significant G.C.A. and S.C.A. for most studied traits indicating that both additive and non-additive genetic variances were important for the inheritance of these traits but, for days to 50% blooming and panicle width, non additive variance play a major role for the inheritance of these traits.  General and specific combining ability effects of the parental lines for the studied traits as well as the best combiner with the lines for the studied traits were discussed.