Combining Abilities for Yield and Yield Components in Diallel Crosses of Six New Yellow Maize Inbred Lines

Ear Length (EL), Ear Diameter (ED), number of rows per ear (RE), kernel number per row (KR) and 100 Kernel Weight (KW) are the most important yield components (YCTs) of grain yield in maize (Zea mays L.).Many investigations have been conducted on grain yield combining ability and the results have been widely used in maize breeding programs.Limited research has been done on combining ability of maize YCTs, however, no reports on the relationship between grain yield combining ability and YCTs combining abilities exist.The objectives of this study were to estimate combining abilities of grain yield and of EL, ED, RE, KR and KW and examine the relationship between grain yield combining abilities and the combining abilities of the YCTs.Both general (GCA) specific (SCA) combining ability and reciprocal mean squares were highly significant for all studied traits excepted Ear Length (EL), Ear Diameter (ED), number of rows per ear (RE) and 100 kernel weight for (GCA) and Ear Diameter (ED) and number of rows per ear (RE) for (r ).The ij ratio of GCA/SCA was less than unity for all studied traits.These results indicating that the non-additive genetic effects were more important and played the major role in all studied traits indicating the non-additive gene was more important than additive gene action.The ratio of GCA/SCA for grain yield and for the YCTs were between 0.006 and 0.65, indicating non-additive genetic effects were more important for these traits.The results showed the general combining ability GCA effects for six parental line indicating that the parental inbred line P was good 4 combiner for Ear Length (EL) and number of rows per ear (RE).The parental inbred line P was 5 good combiner for kernel number per row (KR) and the parental inbred lines P was good combiner for YCTs is very useful for maize breeders to determine which maize line should be selected to improve local lines and which parent lines should be used for making hybrids with greater grain yields.