Genetic diversity in lowland, midaltitude and highland African maize landraces by morphological trait evaluation

Genetic diversity information is a resource for improvement in crop productivity and trait performance, however, there is scanty information on genetic diversity estimates in the maize landraces covering the major geographical regions of Africa. In the current study, the genetic diversity of 35 landraces originating from lowland, midaltitude and highland regions of Africa and held in the IITA Genetic Resource Center, Ibadan, Nigeria, were evaluated using morphological trait evaluation. The landraces were tested in non-stressed environments in Ghana by evaluation of 27 traits. A large within and between genetic variability was identified which increased from highland to lowland populations and was highest in the midaltitude population. Genetic similarity coefficients ranged from 0.00 to 0.80 with mean of 0.26±0.18 across the three populations, and 0.23±0.16, 0.29±0.18, and 0.38±0.25 in the midaltitude, lowland and highland populations, respectively. A total of 21 discriminant traits were identified from the principal components analysis. A UPGMA cluster analysis and PCA biplot produced four main clusters which provide a sound basis for exploitation of heterosis. Nine distant landraces were identified majority of which produced grain yield exceeding 5.0 Mg ha-1. In terms of improvement in grain yield, earliness and drought tolerance, TZm-14, TZm-41, TZm-242, TZm-37, TZm-1360, TZm-1376, TZm-1367, TZm-4, and TZm-270 would be useful. A large genetic diversity resides in the African maize landraces which could be conserved and exploited for maize improvement. Key words: Maize, genetic diversity, African maize landraces, morphological traits, cluster analysis, PCA.