Morphological diversity and relationships among the IPGRI maize (Zea mays L) landraces held in IITA

Genetic variability estimates in maize (Zea mays L) landraces is an important information for trait improvement for food and nutrition security. Genetic diversity information in the Sub-Sahara African maize landraces is lack- ing. Agromorphological trait evaluation is a practical approach for genetic diversity estimation. Our objective was to assess genetic diversity among 60 IPGRI maize landraces held in IITA, Ibadan, against a check, «Obatanpa GH». Twenty-one quantitative traits and five qualitative traits were field-evaluated in Ghana in 2011 and 2012 wet seasons in a three-replicated randomized complete block design experiment. Large phenotypic variation was identified in all traits except cob colour, principal grain colour, and number of ears per plant. A moderate within population variation based on pooled Shannon Diversity Index was 0.68 ± 0.28. Between population variation was largest in earliness, anthesis-silking interval, and grain yield. Genetic similarity of 0.11 ± 0.00 based on squared correlation coefficient confirmed a large variability among accessions. Two major clusters, I and II, were separated on the basis of maturity characteristics, anthesis-silking interval, plant and ear heights, and grain yield. The first two principal components explained 67.89 % of the total variance. Four genotypes, TZm-1125 and TZm-1117 (5.0 Mg ha-1), TZm-1119 (5.4 Mg ha-1), and TZm-1139 (6.2 Mg ha-1) competed with the check (5.8 Mg ha-1) in grain yield. The IPGRI genotypes represent a large genetic reserve awaiting exploitation for trait improvement