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Definition: cowpea from The Columbia Encyclopedia

black-eyed pea, or black-eyed bean, annual legume (Vigna sinensis) of the pulse family. Introduced in the early 18th cent. from the Old World to the S United States, it has become a staple of Southern cooking and an important catch crop, soil enhancer, and forage. Cowpea, sometimes called China bean, is grown commercially in India and China and as a high-protein subsistence crop in Africa. Cowpea is classified in the division Magnoliophyta, class Magnoliopsida, order Rosales, family Leguminosae.


Summary Article: Cowpea
from The Encyclopedia of Seeds: Science, Technology and Uses
1. World importance and distribution

Cowpea (black-eyed pea) (Vigna unguiculata) is a warm-season legume. The seeds are an important food throughout the tropics and subtropics in savanna regions; this includes Africa, Asia, and Central and South America. Southern Europe and the USA are also important producers. Cowpea is an essential component of cropping systems in drier regions of the tropics due to it being fast growing, its ability to fix nitrogen, its tolerance to drought, shade, soils with high or low pH, heat and nematodes plus its ability to curb erosion by covering the ground. Around 9 million ha are harvested in the world (FAOSTAT 2002), 75% of which are in Central and West Africa, mainly in the dry savanna and semi-arid agroecological zones. The principal producing countries are Nigeria (5 million ha-57% of the total cowpea crop area in Africa), Niger, Burkina Fasso (more than 300,000 ha each), Senegal, Ghana and Mali. Nigeria is the largest producer (2,389,000 t) and consumer (2,617,400 t) of cowpea in the world. To cover the deficit, substantial amounts of cowpea come to Nigeria from other African countries. Niger is the largest cowpea exporter in the world (estimated at 215,000 t annually). South America, mainly Brazil (1-1.8 million ha), ranks second in world cowpea production (21%). (See: Legumes; Crop Atlas Appendix, Map 3)

2. Origin

Ethiopia is considered to be the sole centre of origin of cowpea which later spread to the African savanna, through Egypt and Arabia to Asia and the Mediterranean. Cowpea is a variable species composed of wild perennials, wild annuals and cultivated forms. The cultivated cowpea is closely related to annual wild cowpea which may include the likely progenitor of the cultivated form.

3. Plant types

Plants have either a determinate or an indeterminate growth habit, i.e. the flower either does or does not terminate growth of the main stem, respectively. The tendency of indeterminate cultivars to ripen fruits over a long time makes them more amenable to subsistence rather than to commercial farming. Determinate types are more suited to a monocultural production system.

4. Seed characteristics

The globular to reniform (kidney-shaped) seeds are 2-12 mm long, smooth to wrinkled, and red, white, brown, green, buff or black as dominant colours (Colour Plate 1E). They may be plain, spotted, marbled, specked, eyed or blotched; seed weight varies from 5 to 30 g/100 seeds.

5. Uses

Cowpeas are cultivated for the seeds, shelled green or dried, and the pods and leaves that are consumed as green vegetables. The plants are also used for pasturage, hay, ensilage and green manure.

6. Nutritive value

The composition of cowpea is in general similar to that of most edible legume seeds, with a range of contents of protein, starch, and sugars in the different types. Table C.24 shows the nutrient content range of cowpeas based on several reports in the literature.

Cowpea protein is rich in lysine, but it is deficient in sulphur amino acids. Its relative contents of methionine and tryptophan are higher than those of the other legumes.

7. Anti-nutritional factors

Cowpeas contain relatively high amounts of flatulogenic sugars particularly raffinose, the most active in this respect. The concentrations of trypsin inhibitors and phytin are half of those in soybean.

8. Market classes

To develop cowpea markets it is essential to know consumer preferences. Seed colour and size and usage are important factors. The following types of cultivars are recognized:

  • ‘Crowder peas’: globose, crowded in pods, black, speckled brown, brown-eyed.
  • ‘Brown Crowder’: brown.
  • ‘Black-eyed’: white seeds with black-eye around the hilum; not crowded in pods.
  • ‘Cream’: cream seeds, not crowded in pods.
  • ‘Purple Hill’: deep purple, mature pods and buff or maroon-eyed seed.
  • Snap: good for use as vegetable.
  • Persistent-green: new market class of cowpea for the freezing industry.
  • Dual-purpose: provide food (dry seeds) and forage.

The West African consumer in general prefers larger seeds. In some countries, Cameroon and Ghana for example, the eye colour is an important influence on the price: in Ghana consumers pay a premium for black-eyed cowpea while in Cameroon they expect a discount. In Ghana, there may be a price reduction or a premium on white grains according to the region.

9. Marketing and economics

Cowpea marketing in West Africa is based on the comparison in food production between the humid coastal zone, where it is relatively easy to produce carbohydrates but not vegetable protein, and the semi-arid interior where low rainfall creates good conditions for cowpea and groundnut.

Table C.24. Cowpea seed composition.

Component

Content (% fresh weight)

Protein

20.3-32.5

Crude fibre

2.7-6.9

Carbohydrates

59.7-71.6

Soluble sugar

5.9-8.3

Starch

39.1-54.9

Ash

2.9-3.9

Oil

1.1-3.0

In the Sudano-Sahelian zone there is a well developed network of village buyers who assemble small amounts from farmers into 100 kg quantities and the merchants who transport and store these large batches. Ghana imports cowpeas in this way from Burkina Faso and Niger. Cowpeas from the latter-large, rough-coated grains-sell for a premium, but they need to be marketed quickly as they do not store well in the humid coastal climate. There is an active trade among Benin, Niger, Togo, Nigeria and Gabon.

In 2001 the USA exported 4487 t of the black-eyed type of cowpea, mostly produced in California, for a value of $2,217,000. Countries in Latin America (e.g. Ecuador and Peru) also export small quantities of cowpea for canning purposes.

  • Singh, B.B., Mohan Raj, D.R., Dashiell, K.E. and Jackai, L.E.N. (eds) (1997) Advances in Cowpea Research. International Institute of Tropical Agriculture (IITA) and Japan International Research Center for Agricultural Sciences (JIRCAS). IITA, Ibadan, Nigeria.
  • Singh, S.R. and Rachie, K.O. (eds) (1985) Cowpea Research, Production and Utilization. John Wiley, New York.
  • Som, M.G. (1993) Cowpea, Vigna unguiculata (L.) Walp. In: Kalloo, G. and Bergh, B.O. (eds) Genetic Improvement of Vegetable Crops. Pergamon Press, Oxford, UK, pp. 339-354.
  • Voysest-Voysest, Oswaldo
    © CAB International 2006.

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