|Although the centre of domestication for cowpea is uncertain, all evidence points to its originating in Africa. Ethiopia, Central, Southern and West Africa have all been considered probable centres of domestication.
Recent studies of more than 10,000 accessions of the world cowpea collections at IITA revealed that germplasm accessions from Nigeria, Niger, Burkina Faso and Ghana showed greater diversity than those from East Africa, with the centre of diversity in Nigeria. These studies provide further evidence that West Africa was the primary centre of domestication.
The plant architecture and growth habits of cowpeas are diverse because genotypes and environments interact to influence both the numbers and the lengths of their branches. At one extreme are bushy, erect types with short branches, at the other prostrate, spreading or sometimes twining and climbing forms with five (5) or more orders of branching and first and second order branches up to 5 m long.
Each axillary inflorescence is a compound raceme of several simple racemes carried on a grooved peduncle 5-60 cm. Each simple raceme has between six and twelve flower buds, but only the lower, first formed pair develops while the rest degenerate to form extra-floral nectarines between the paired flowers.
The leaflets are ovate to lanceolate, sometimes hastate, 5-18 cm long and 3-16 cm wide, entire or lobed and sub-tended by inconspicuous stipules. In the axil of each leaf there are three buds. Only the central bud normally expands to produce either a potentially indeterminate, monopodial branch or a racemose inflorescence. Consequently, the number of branches is the complement of the number of inflorescence. Rare determinates have terminal inflorescence on their main stem and branches, such types may have more than one inflorescence and a reduced branch at a single node.
The cleistogamous flowers are typically papilionaceous and are large, with a standard petal 2-3cm wide which is either white or with anthocyanin pigmentaion in shades or pale mauve or pink to dark purple, with or without a "V" shaped distribution at the top centre of the petal.
Mature fruits vary widely in size, shape, colour and texture. Fruit lengths range between 12-20 cm and are straight, curved or coiled. They may lack pigmentation (tan or straw coloured) or have varying intensities of anthocyanin pigmentation from pink purple or almost black. They contain between six and twenty-one kidney shaped, oval or, rarely, almost spherical seed whose dimensions is within the range 5-12 mm and with individual weights between 50 mg and 340 mg. The testa may be smooth or wrinkled and rough. Testas may be white, buff brown, red and black.
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|Origin And Botany | Varietal Development And Maintenance | Land Selection | Land Preparation | Planting | Fertilization | Irrigation | Weed Control | Plant Protection | Roguing | Harvesting|