Morphometric Analysis of some Species in the Genus Vigna (L.) Walp: Implication for Utilization for Genetic Improvement
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Asian Network for Scientific Information
Abstract
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The genus Vigna (L.) Walp is a large cosmopolitan leguminous genus comprising
both cultivated and wild species. Vigna unguiculata (L.) Walp. (Cowpea) is an
important food legume that is widely cultivated in the tropics, but its production and
storage are hampered by insect pests. The present study evaluated the intra-and
inter-specific morphological variabilities among 20 accessions of six Vigna species,
comprising wild and cultivated species. The species are Vigna unguiculata (L.)
Walp, V. vexillata (A. Richard), V. oblongifolia (A. Richard), V. ambacensis
(Baker), V. luteola (Jacq.) (Bentham) and V. racemosa (G. Don) (Hutch and
Dalziel). Thirty-one morphological characters involving qualitative and quantitative
vegetative and reproductive traits were used for the evaluation. Multivariate
analysis such as Pearson Correlation Coefficient (PCC), Principal Component
Analysis (PCA) and Cluster Analysis (CA) were employed to evaluate the intra and
inter specific variabilities. The paired-sample T test indicated significant differences
among the 20 accessions (p#0.000, df = 19) in their morphometric traits. The
relative significant correlation observed among some traits such as pod length,
number of locules per pod and number of seeds per pod indicated their closeness
and potential for genetic improvement of cowpea. The PCA showed that
reproductive traits such as days to 50% flowering (0.984), days to 50% ripe pod
(0.993), number of pods per peduncle (0.340) and 100-seed weight (0.132) are the
major traits that accounted for the variations among the species. The UPGMA using
the average (between groups) segregated the 20 accessions into two main clusters,
cluster I (comprising mainly wild Vigna species) and cluster II (comprising both
wild and cultivated species). The taxonomic affinities and genetic diversity among
the species are of great importance in the utilization of the species for food and
nutrition, fodder for ruminant animals, cover crop for rotational farming and more
importantly genetic improvement of cowpea.
Keywords
QH Natural history, QH301 Biology