Vigna subterranea (PROSEA)

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Plant Resources of South-East Asia
Introduction
List of species


Vigna subterranea (L.) Verdc.

Protologue: Kew Bulletin 35 (3): 474 (1980).
Family: Leguminosae
Chromosome number: 2n= 22

Synonyms

  • Voandzeia subterranea (L.) Thouars (1806).

Vernacular names

  • Bambara groundnut (En)
  • voandzou (Fr)
  • Indonesia: kacang bogor.

Origin and geographic distribution

Origin is most probably northern Nigeria and Cameroun. The species is mainly cultivated throughout the drier areas of tropical Africa, but has also spread to America, Australia, central Asia, Indonesia, Malaysia and the Philippines.

Uses

Roasted or cooked (ripe pods in salt water) seeds are eaten as a delicacy. Seeds and young pods are added to spicy soups. The main use in Africa is as a pulse, for instance to prepare a porridge.

Production and international trade

World production is estimated at 330 000 t/year, about half of which is produced in West Africa. No reliable statistics exist for South-East Asia, where production and consumption are local.

Properties

Per 100 g edible portion the seeds contain: water 11 g, protein 18 g, fat 6 g, carbohydrates 62 g, fibre 5 g, ash 3 g. The energetic value averages 1540 kJ/100g. As in other legume seeds, the sulphur-containing amino acids, cystine and methionine, are limited, whereas the quantity of lysine is relatively high. Seed weight varies between 50 and 75 g/100 seeds.

Botany

  • Bunch-shaped to spreading annual herb with creeping much branched stems. Roots with lobed nodules.
  • Leaves trifoliolate, glabrous, with erect, up to 30 cm long, grooved petioles; leaflets elliptic to oblanceolate, up to 8 cm x 4 cm.
  • Racemes with (1-) 2 (-3) whitish-yellow flowers.
  • Fruits subterraneous, subspherical, about 2.5 cm in diameter, usually with only 1 white, yellow, red-blackish or variously mottled seed.

Germination is hypogeal, 7-15 days. Flowering starts 30-55 days after sowing. Usually self-pollination occurs. The pod develops in about 30 days after fertilization. Then the seed expands during the following 10 days. Seeds are mature when the parenchymatous layer surrounding the embryo has disappeared and brown patches appear on the outside of the pod. Maturity is reached 90-150 days after sowing.

Ecology

Bambara groundnut, a short-day plant, is cultivated in the tropics at altitudes up to 1600 m. A frost-free period of at least 3.5 months is necessary. The plant prefers bright sunshine and average day temperatures between 20 and 28 °C. The crop can be cultivated successfully in areas with a rainfall of approximately 600-750 mm, but optimum yields require 900-1200 mm per year. The plant will grow on any well-drained soil, but light sandy loams with a pH of 5.0-6.5 are most suitable.

Agronomy

Bambara groundnut performs best on a deeply ploughed field with a fine seedbed, which enables the plant to bury its peduncles with fertilized flowers. Average seed rates vary from 25-75 kg/ha. Recommended spacing in pure stand on the flat is 10-15 cm apart in single rows at a distance of 45 cm, and 20 cm apart in double rows on flat-topped ridges at 90 cm distance. As an intercrop bambara groundnut is combined with cereals, root and tuber crops, and other legumes. After a well-fertilized preceding crop a maintenance dressing with superphosphate is recommended, and soils of low fertility require an application of compound fertilizer. The crop should be weeded ca. 15 days after emergence and again before the clusters join. In general, pests and diseases do not reduce yields seriously. Harvesting is done by hand-pulling when the leaves turn yellow and wither. Since pods may break from the plant on lifting, gleaning is very important. Seed yield in Africa averages 650-850 kg/ha with large differences between countries. For South-East Asia no statistics on yields are available. Seeds stored in the shell suffer less from deterioration and infestation by insects than shelled seeds.

Genetic resources and breeding

The largest germplasm collection is held by the IITA in Nigeria. So far breeding is for high yields.

Prospects

Bambara groundnut is a promising crop for semi-arid areas since it tolerates drought and poor soils better than many other crops.

Literature

  • Adenaike, B.O. (Editor), 1978. Bambara groundnut (Voandzeia subterranea Thouars): abstracts of world literature 1900-78. IITA, Ibadan, Nigeria. 55 pp.
  • Linnemann, A.R., 1987. Bambara groundnut (Vigna subterranea (L.) Verdc.) - a review. Abstracts on Tropical Agriculture 12 (7): 9-25.

Authors

  • A.R. Linnemann