Evaluation of genotype x year interaction in extra-early maturing maize hybrids in a typical Southern Guinea Savannah Ecology

Abstract

In Nigeria, genotype by environment interaction effect on maize grain yield is usually significant due to considerable variation in soil and weather conditions of the growing sites. This also complicates identification and selection of superior genotypes in a particular environment. Consequently a proper understanding of the effects of G x E interactions on varietal evaluation and cultivar recommendations is vital. This study was therefore conducted to evaluate performance of drought tolerant maize hybrids of different maturity groups. The first group comprised twenty-four extraearly yellow and the second comprised seventeen early white QPM hybrids, both obtained from the International Institute of Tropical Agriculture (IITA), Ibadan. The genetic materials were evaluated in replicated trials during the 2012 and 2013 growing seasons at the Teaching and Research Farm, University of Ilorin, in a typical Southern Guinea Savanna ecology of Nigeria. The effects of genotype (G), year (Y) and G × Y were found to be highly significant (P< 0·01) for grain yield in the extra-early yellow hybrids (EEYH) while among the early white QPM hybrids, genotypic (G) effect was significant only for days to silk and plant height. G x Y interactive effect was however significant only for days to silking. Hybrids EEYH 5, EEYH-27 and EWQH-3 were consistent among the top 5 ranking genotypes for both years in terms of grain yield, an indication for stability to this ecology. Correlation between grain yield and associated traits showed that ears per plant and plant height contributed significantly to grain yield in both groups. Regression analysis of grain yield and other associated traits also revealed that ears per plant contributed significantly to grain yield in extra early yellow hybrids while plant height contributed significantly in the early white QPM hybrids. Therefore, selection programme should give attention to ears per plant and plant height in the varieties intended for drought prone ecology of the Southern Guinea Savanna of Nigeria. Keywords: Genotype, Maize, Hybrids Early-maturing, Extral-early maturing