Study of gene action in different traits of maize (Zea mays L.)

A study was conducted on maize incorporating a total of 28 single crosses, eight parental lines and two standard checks to determine the combining ability and gene action. Among the eleven traits that were studied, the analysis of variance revealed that the mean squares due to genotypes, parents and hybrids were highly significant for all traits, except for 100 grain weight in case of parents, indicating the presence of an adequate amount of genetic variability. On further analysis of variance for combining ability, the mean squares due to GCA and SCA were observed to be highly significant for almost all traits indicating the role of both additive and non additive components of genetic variance in the expression of all the studied traits. The  high gca effect for grain yield per plant was associated with high or average gca for yield component traits for most parents, while the poor combiners for grain yield per plant were also poor combiners for other yield component traits. High sca effects were seen in a few cross combinations which were good specific combiners for grain yield per plant and yield component traits. Based on the gca effects some inbred lines were identified as good general combiners for various traits. This indicated that these parents could be utilized for developing synthetic variety. The inbred lines with desirable gca effects for grain yield and other agro-morphological traits could be inter-crossed to develop an improved base population and subsequent recurrent selection efforts would facilitate the derivation of elite lines excelling in desirable character. All of the cross combinations exhibiting desirable significant sca effect were having one parent as a good or average combiner for each of the eleven agro morphological traits studied. It was clear that these hybrids were the combinations of either  the parents as good general combiners or one of the parents as a good general combiner for yield and yield related traits. Hence, they can be used as a potential single cross hybrid combination and tested further. The crosses that show high sca effects indicate a preponderance of non-additive genes and can be used for heterosis breeding.