Vigna unguiculata (L.) Walp.
Vigna unguiculata (L.) Walp. subsp. dekindtiana (Harms) Verdc.

Vigna is found throughout the tropics with some 150-190 species. Classification of cultivated cowpea is now based on five so-called cultivar-groups (cv.-gr., also "cultigroups"):  Unguiculata, Biflora, Sesquipedalis (= the former subspecies unguiculata, catjang and sesquipedalis), Textilis and Melanophtalmus.

Vigna sinensis (L.) Savi
Vigna sinensis Endl.
Vigna catjang (Burm.) Walp.

Family: Fabaceae (alt. Leguminosae) subfamily: Faboideae tribe: Phaseoleae subtribe: Phaseolinae.  Also placed in: Papilionaceae .

cowpea, caupi, southern pea, tua dam, kunde, ni�b�, blackeye pea, alac�n, pericillo, caritas, cabecita negra, macassar bean, rope bean, fr�jol (Venezuela), Augenbohne or Kuhbohne (Germany).

Variability in plant morphology of the different accessions is high.  There are three types according to their uses:  for grain, forage or dual-purpose.  V. unguiculata is a herbaceous, prostrate, climbing, or sub-erect to  erect annual, growing 15-80 cm high.  Leaves are alternate, trifoliolate with petioles 5-25 cm long.  The lateral leaflets are opposite and asymmetrical, while the central leaflet is symmetrical and ovate.  Inflorescence racemose, flowers white, cream, yellow, mauve or purple.  There are accessions with determinate and with indeterminate growth habit.  Pods 10-23 cm long with 10-15 seeds/pod.  Seeds are variable in size and shape, square to oblong and variously coloured, including white, brown, maroon, cream and green, commonly in the range of 5,000-12,000 seeds/kg.

Native to:
West Africa, where the highest genetic diversity and the most primitive forms of wild V. unguiculata occur, was probably the primary centre of domestication.

Today, cowpea is cultivated throughout the tropics and subtropics between 35ºN and 30ºS, across Asia and Oceania, the Middle East, southern Europe, Africa, southern USA, and Central and South America.

Cowpea is one of the most widely used legumes in the tropical world.  The grain is used widely for human nutrition, especially in Africa.  It is one of the most important tropical dual-purpose legumes, being used for vegetables (leaves and flowers), grain, as fresh cut and carry forage, and for hay and silage .  Mixing of different cowpea varieties for food and feed purposes is common in northern Nigeria.
The species has a high potential as a green manure.  It can be incorporated into the soil or spread on the soil surface 8-10 weeks after sowing, and can provide the equivalent of 80 kg/ha N to a subsequent crop.  In trials, maize grain yields, associated with the use of cowpea as green manure , have been doubled compared to unfertilised control treatments.  Also, maize grain yields were 30% higher than those from treatments which had 80 kg/ha of inorganic N fertilizer applied.  Estimates of fixed nitrogen from cowpea often range from about 50 to in excess of 100 kg/ha.
In Australia, cowpea is grown as a green manure crop in coastal sugarcane areas, as a forage or dual-purpose grain and forage crop in coastal and subcoastal southern Queensland, and as a grain crop from central Queensland to central NSW.
Cowpea has the potential to make excellent hay.  When grown specifically for this purpose, quality can equal lucerne hay.  Even in smallholder systems, when used as a dual-purpose legume, residues can be used as animal feed or for soil enhancement.  E.g. in West Africa cowpea hay is an important product for sale in local markets. Excellent hay, and particularly silage, can be made by harvesting a mixed crop of cowpea and forage sorghum or millet.
V. unguiculata subsp. dekindtiana may have potential as a forage plant.  Some accessions have been evaluated for use as ley pastures on alkaline clay soils in southern Queensland in recent years.  Yields have reached 6 t/ha in the first year and usually match the yields of other well-adapted legumes.  However there was little seedling regeneration in the second year at all sites and so there appears to be little advantage in this subspecies over late flowering cowpeas or lablab (Lablab purpureus ).  Other legumes such as burgundy bean, Macroptilium bracteatum , are likely to be of more value if short-term phase legumes pastures of 2-3 years are being sought.

Adapted to a wide range of soils from sands to heavy, well-drained clays, with a preference for lighter soils that allow good rooting.  Wide range of pH including very acid (pH 4), low-fertility soils.  Better adapted to strongly acid soils than either Lablab purpureus or Mucuna pruriens .  Grows well also on heavy textured strongly alkaline soils.  Does not tolerate extended flooding or salinity.

Moderately tolerant of drought but excessive soil moisture is harmful, reducing growth and favoring infection by fungal diseases.  Nevertheless, well adapted to a wide precipitation range (650-2,000 mm).  For forage, annual rainfall regimes of 750-1,100 mm are preferable.  As a food crop for humans, often grown in annual rainfall regimes as low as 400 mm.  Extended water logging or poor drainage should be avoided.

Very susceptible to frost;  grows well only in warm seasons with 25-35°C as optimum temperature.  Grows from sea level up to 1,500 m asl , depending on latitude.

Moderate adaptation to shade.

The different cowpea accessions can show wide variation in reproductive development.  Some may start flowering 30 days after sowing and are ready for harvest of dry seeds 25 days later;  others may take more than 90 days to flower, and 210-240 days to mature.  Many cultivars mature uniformly although there are determinate and indeterminate genotypes.  Indeterminate types are particularly useful in smallholder farming systems where a supply of fresh leaves and flowers, over an extended period of time enables a sustained supply of vegetables for the household. Determinate types are better for machine harvesting.  Cowpea is mostly a quantitative short-day plant, but there are also day-neutral cultivars.  Planting out of season or taking seed of photoperiod sensitive genotypes to different latitudes, may inhibit seed set.

When seasons are suitable and when sown relatively early, the best forage types will regrow after grazing.  Grazing should be light to ensure that the plant frame is retained and damage is limited.

Not tolerant of fire.

Guidelines for the establishment and management of sown pastures.

Sowing arrangement according to intended use:  for fodder and green manure, 30-60 cm between rows and 10-15 cm between plants are suitable;  required seeding rate about 20 kg/ha.  Other seeding rates reported are 10-40 kg/ha when sown in rows and up to 90 kg/ha when broadcast.  Most common 20-50 kg/ha.  Sowing depth 3-5 cm.  Seed is soft so germination is usually rapid if moisture and temperature are adequate.  V. unguiculata subsp. dekindtiana usually has a high proportion of hard seed, and may need scarification prior to sowing.  Promiscuous in its rhizobial requirements.
Annual grasses and some broadleaf weeds can be controlled by a pre-sowing application of trifluralin which is the only herbicide registered for use on cowpea in Australia.

Responses have been recorded to P, K and S as well as molybdenum on poor fertility soils.

Grows well in association with cereal crops through intercropping .

Is widely used in intercropping of the major African cereals, maize, sorghum and millet.

Susceptible to a wide range of diseases and pests (including post-harvest) , particularly those attacking the grain.  Cowpea acts as host to pests of Phaseolus beans.  The most important disease in Australia is phytophthora stem rot (Phytophthora vignae ).

Commercial cowpeas are soft seeded annuals and have little potential for survival in the soil.

None.

High nutritive value:  CP in green foliage 14-21% and in crop residues 6-8%, in grain 18-26%;  IVDMD of foliage >80%.  IVDMD of residues after grain harvest 55-65%.

Very palatable, high intake.

None for ruminants;  for monogastrics, trypsin inhibitors and some content of tannin need to be taken into account.  20-25% of grain in diet fed without treatment seems not to pose a problem.  Heat treatment reduces trypsin inhibitors.

Vegetative DM production 3-10 t/ha in 8-12 weeks;  grain production 250-4,000 kg/ha.

Very few studies available;  when fed as supplement, 10-20% increase in milk yield (Colombia) and 50% higher animal LWG (67 g/day with sheep) are reported (West Africa).

2n = 22;  primarily self-pollinating.

Large variation in seed production depending on cultigroup, landrace and use.

No information available.

• Multi purpose legume providing leaf, grain and forage .
• Improves soil fertility .
• Ease of establishment.
• Very high nutritive value and high palatability .
• Adaptation to a wide range of soils, better adaptation to acid soils than other crops used for green manure .
• Drought tolerant.
• High yields in a short period of time.
• High seed production.

• Pest and disease susceptibility, host for pests of Phaseolus beans.

http://www.fao.org/ag/AGP/AGPC/doc/Gbase/data/pf000090.htm
http://www.agric.nsw.gov.au/reader/forage-fodder/p4216.htm#ANIMAL%20PRODUCTION