Combining Ability, Heterosis and Gene Action Estimation by Using Line X Tester Analysis in Bread Wheat (Triticum astivum, L)

In order to investigate the combining ability, gene action and heterosis morphological, yield and its components traits in wheat F1 crosses using line x tester analysis. Experiment was conducted with sixty three genotypes consisting of fifteen lines, L1,L2, L3, L4, L5, L6, L7, L8,  L9, L10,  L11, L12, L13, L14, L15.and three testers namely; Gemmeiza 9 (T1), Giza 171 (T2) and Gemmeiza 11 ((T3) and heir forty five crosses made in line x tester mating at experimental Research Farm, Faculty of Agric., Tanta University during the winter successive growing seasons 2014/15 and 2015/16. A significant difference was found among lines, testers and line x testers for all the studied traits. Analysis of genetic revealed that GCA and SCA variances were significant for all traits, indicating the importance of both additive and non-additive components in the inheritance of thesis traits. The non-additive was more important for all the studied traits except days to heading and No. of grains/spike in which the additive was more important.The best general combining ability for earliness (Number of days to heading and maturity) were L5, L7, L9, L10 and L14for short plant were L2, L6, L10, L12 andL13 for spikes numbers/plant, grains numbers/spike and grain yield/plant were the parental lines L11 and L12. The best crosses for heterosis relative to mid parent and better parent were T1 x L7 and T1 x L9 for number of days to heading and maturity, while the cross T3 x L11 for spikes numbers/plant, grains number/spike and grain yield/plant.Heritability in broad sense were greater than the corresponding values of narrow sense for all the studied traits. Higher value for narrow sense 10.22% was obtained for days to maturity, while the lowest value 3.96 was detected for No. of grains/spike. The lines had higher contribution to the total variance than both testers and lines x testers, also the line x testers contribution were higher than the testers for all the studied characters excluding number of days to heading.