GROWTH CONDITIONS
Day length: short-day, long-day and day-neutral types exist.
Growth period: 90–240 days for grain is normal, though 60 day varieties are
available, 50–100 days for green pods, depending on the variety and growth
conditions. Most cowpeas are indeterminate (1Ei) so their pods and grain mature
unevenly.
Temperature: ideally the soil should be no less than about 20C at planting. The
optimum for growth is about 20-35C. The plants are frost sensitive, and young
plants are weakened below about 10C.
Rainfall: 600 mm per year is enough for some early, determinate types. High
rainfall or humidity tends to reduce yields due to an increase in fungus diseases;
asparagus beans tolerate high rainfall better than common cowpeas.
Altitude: in East Africa they are grown up to about 1500 m.
Pests: probably the most serious problem with cowpeas, which are attacked by more
than 100 different insect species, such as pod borers (Maruca testulalis), blossom
beetles (Coryna spp.), thrips, root-knot nematodes and a pod-sucking insect
(Acanthomia horrida).
Diseases: also a big problem. The most important are rust, bacterial canker, cowpea
(fusarium) wilt, mildew, charcoal rot, anthracnose and several virus diseases. In
Africa, leaf and pod spot (Ascochyta) is often a problem; although fungicides can be
effective, the best control is by using resistant varieties, crop rotation, and by
destroying all diseased plant material in the field.
YIELD
Although the potential yield of improved varieties of cowpeas with good
management is more than 4 MT/ha, the average grain yield for African subsistence
farmers is about 300–600 kg/ha (though pure stands (monocropping) are rarely
found in subsistence farming systems).
Croatia of 4 MT/ha to a low in Niger of 157 kg/ha.
When grown for hay, 5 MT/ha is an average yield.
UTILISATION
Cowpeas are an important food legume, especially in Africa; the dried
seed/grain is almost always the part that is eaten. The objective of much of the
current research in Asia and Africa is more towards increasing the utilisation of
cowpeas in the human diet than to improve the agronomy of the crop.
Cowpea seed is highly nutritious and palatable, containing about 22% protein
(up to 35%), 1.3–2% fat and 60–67% carbohydrate. The energy value is a
respectable 340 calories/100g of edible portion. The proportion of protein,
carbohydrate and Vitamin B varies considerably according to the variety and
origin of the seed. Like most legumes, the amino acid profile complements
cereal grains.
The green grain, pods or young shoots can be eaten as a vegetable; or the leaves
are boiled, then either eaten or dried and stored for use in the dry season.
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FAO estimated the global average yield in 2004 was 388 kg/ha, from a high in
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160 TONY WINCH
