Abstract
A set of twenty four cowpea (Vigna unguiculata L. Walp) genotypes were evaluated in field conditions for three consequtive seasons based on 13 quantitative characters. A combined analysis of variance revealed a highly significant difference among the genotypes for most of the traits (P <0.001). Introduced genotypes performed better in nine of the characters, revealing the advantage of introduced genotypes. Principal Component Analysis explained a total variation of 76.16%, where the first two PCs accounted for 51%. Most variation was largely dependent from rainfall use efficiency, days to maturity, seed yield per hectare and pod width. Cluster analysis dendrogram delineated the 24 genotypes into two major clusters, with a mixture of local and introduced in both groups which indicated their potential relationship. Exceptional local genotypes B137B, with highest seed yield (866 kg/ha), and the singleton B342 with a number of desirable agronomic traits must be included in future cowpea breeding programs in Botswana. Key words: Cluster analysis, rainfall use efficiency, SPAD reading, Vigna unguiculata.
Highlights
Cowpea (Vigna unguiculata (L.) Walp) is a crop with wide global distribution, especially in tropical regions
Low cowpea productivity and production is attributed to several factors such as biotic and abiotic
Twelve are local lines sourced from the cowpea breeding program but originally from the National Plant Genetic Resource Centre (Botswana), while the other 12 were introduced genotypes from various countries and institutions
Summary
Cowpea (Vigna unguiculata (L.) Walp) is a crop with wide global distribution, especially in tropical regions. It is an important grain legume crop in sub-Saharan Africa, with significant production in Nigeria, Burkina Faso, Niger, Cameroon and United Republic of Tanzania (Fatokun et al, 2012; FAOSTAT, 2017). Cowpea is a high valued crop due to its high quality protein, adaptation to heat and drought, and ability to fix nitrogen. These characters make it a major crop in the context of climate change and food security (Carvalho et al, 2017). Low cowpea productivity and production is attributed to several factors such as biotic and abiotic
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