ALIU D. AFEKHAI, CHIBUZO N. C. NWAOGUALA AND JOSEPH E. ALIKA
Department of Crop Science, Faculty of Agriculture, University of Benin, Benin City, Edo State, Nigeria
The study was conducted to estimate general combining ability (GCA) and specific combining ability (SCA) of 13 maize cultivars on grain yield and component traits using North Carolina mating design II (NCII). Genotype x environment interaction for the agronomic traits was also estimated. Crossing was carried out among thirteen elite maize cultivars which were planted in November 2014 under irrigation. The progenies were evaluated in April, 2015 during the early season and in August 2015, for the late season. Data were subjected to analysis of variance (ANOVA) and thereafter, GCA and SCA were estimated. The results showed that there was little variation among parental genotypes in the early season while in late season, the parents exhibited wider variations in yield component traits evaluated. GCA/SCA ratio showed preponderance of specific combining ability (SCA) effects for all the yield component traits studied in the early and late cropping seasons except for number of grain rows/ear and number of grains/row. This implies that SCA was more important in these maize cultivars as parents to hybrid or synthetic variety populations. Highly significant differences were observed for genotypes x season interaction in almost all the characters, indicating that selection should be carried out on seasonal basis. Five top performing hybrid genotypes were identified and selected based on grain yield from each of the seasons: (11A11990)*(11A11917); (11A11990)*(07A04207); (11A11990)*(11A11991); (11A11936)*(11011896) and (09A2567)*(11A11895) for the early season and (11A11990)*(11A11991); (11A11936)*(11A11991); (12C24114)*(11011896); (11A11990)*(11011896) and (11A11936)*(12C24117) for the late season. These genotypes are therefore recommended for use in population improvement programme.
Keywords: General combining ability, specific combining ability, genotypes, North Carolina Design II.