Prota 2: Vegetables/Légumes
Mart., Fl. bras. 15: 194 (1859).
Papilionaceae (Leguminosae - Papilionoideae, Fabaceae)
2n = 22
Vigna fischeri Harms (1899).
Hairypod cowpea, dalrymple vigna, deer pea (En).
Origin and geographic distribution
Vigna luteola occurs throughout the tropics and is widespread in mainland Africa. It has been grown on research stations in Réunion and Mauritius.
The flowers of Vigna luteola are eaten as a boiled vegetable in Ethiopia and Malawi. In Malawi the roots are dug up by children, peeled and chewed to extract a sweet juice. The tender cooked seeds are edible.
Because it is palatable for livestock and grows and nodulates well in wet and slightly saline soils, Vigna luteola has been tested as a pasture plant and cover crop in a number of countries including Ghana, Zambia, Argentina, Cuba and Australia. However, disadvantages as a pasture crop are its rather short life cycle, susceptibility to frost and to insect pests, and troublesome seed production.
In Ethiopia the leaves and flowers are mixed with Hagenia abyssinica (Bruce) J.F.Gmel. flowers to treat syphilis and ulcers. In Argentina the plant is used to control lipid adsorption and cholesterol levels, and it is also reported to have antimicrobial and antineoplastic properties.
With a crude protein content of 17.4% of dry matter at flowering Vigna luteola qualifies as an excellent fodder. The flavonoids quercetin and isorhamnetin, isolated from the leaves, are thought to play a role in the resistance mechanism against aphids. The seeds contain high levels of antimetabolic factors (tannins, phytic acid, inhibitors of trypsin and cystatin) implied in the resistance to storage pests. High levels of the amino acid cystine are present in the seeds.
Twining or trailing perennial herb; stem up to 6 m long, hairy but glabrescent. Leaves alternate, 3-foliolate; stipules up to 5 mm long; petiole up to 8.5 cm long, rachis 0.5–2 cm long; leaflets ovate-lanceolate to lanceolate, 2.5–10 cm × 0.5–4.5 cm, base rounded or cuneate to truncate, apex acute to obtuse. Inflorescence an axillary false raceme; peduncle 12–35 cm long, rachis up to 5.5 cm long, with flowers in pairs at each node. Flowers bisexual, papilionaceous, 1–2 cm long, yellow. Fruit a linear, curved pod, slightly constricted between the seeds, 5.5–8 cm long, with short curved beak. Seeds up to 4.5 mm × 3.5 mm.
Vigna comprises about 80 species. However, the tropical American species are likely to be placed in a separate genus in the near future, which would reduce the genus to 50–60 species. Important crops that belong to the genus are cowpea, mung bean, rice bean and bambara groundnut. A hairy variant of Vigna luteola, formerly known as Vigna fischeri, is common in East Africa at higher altitudes (over 1500 m).
The blue-flowered Vigna membranacea A.Rich. is found in DR Congo, Burundi and throughout East Africa; in Kenya the leaves are eaten after frying or boiling and are said to taste like cowpea leaves.
Vigna luteola is nonspecific in its Rhizobium requirement. It is day-neutral and flowers throughout the year.
Vigna luteola grows in swampy grasslands, among reeds on sandy lake shores, in papyrus swamps, on stream sides and in swamp forest, from sea-level up to 2200 m altitude. It prefers an annual rainfall of 1250 mm or more.
As a pasture plantVigna luteola does not tolerate heavy grazing or close cutting, and under such conditions will behave like an annual or short-lived perennial. Yields of 4500 kg/ha dry matter per rainy season have been reported from Zambia. In Samoa Vigna luteola fixed up to 126 kg/ha nitrogen in grass-legume mixtures in the first year. It is considered a weed of rice in South America, and in South Africa it figures on the national weed list.
Seed harvest is difficult owing to its indeterminate flowering habit. Pods are hidden by new growth before they can be picked, and so hand harvesting has been the only method employed to date. The pods shatter.
Genetic resources and breeding
An important germplasm collection of Vigna luteola is held at IITA, Ibadan, Nigeria. Accessions are also held at CIAT (Colombia) and ILRI (Ethiopia). Vigna luteola is used as a source of resistance and improved nutritive value in cowpea breeding. A method has been developed for recovery of interspecific hybrids of mung bean (Vigna radiata (L.) R.Wilczek) and other Vigna species that were previously difficult to hybridize, including Vigna luteola.
Vigna luteola can be used in breeding programmes of other Vigna species. As a pasture legume and cover crop it might become more important in wet and saline conditions.
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Correct citation of this article:
Bosch, C.H., 2004. Vigna luteola (Jacq.) Benth. In: Grubben, G.J.H. & Denton, O.A. (Editors). PROTA 2: Vegetables/Légumes. [CD-Rom]. PROTA, Wageningen, Netherlands.