Prota 1: Cereals and pulses/Céréales et légumes secs
Bull. Misc. Inform. Kew 1915: 382 (1915).
2n = 54
Black fonio, iburu, black acha (En). Fonio noir, manne noire, ibourou (Fr).
Origin and geographic distribution
Black fonio is cultivated as a cereal in scattered localities from Côte d’Ivoire to northern Nigeria and southern Niger, and in Cameroon. It has also been reported to be grown in Guinea and DR Congo. Black fonio is only known from cultivation. Its origin is uncertain, but it may have been derived from Digitaria ternata (A.Rich.) Stapf.
Black fonio is a staple food of the Birom people of the Jos Plateau in northern Nigeria and an important supplementary food to people in the Atakora mountains of Togo and Benin. It is eaten as porridge or mixed with meal of other cereals. The grain is also eaten cooked like rice or in stews. In Benin and Nigeria black fonio is made into couscous. In Togo it is used for brewing beer (‘tchapalo’).
The composition of whole black fonio grain per 100 g edible portion is: water 10.3 g, energy 1436 kJ (343 kcal), protein 8.9 g, fat 3.0 g, carbohydrate 75.6 g, fibre 6.2 g, P 234 mg and Fe 10.0 mg (Leung, Busson & Jardin, 1968). The essential amino-acid content per 100 g grain is: tryptophan 215 mg, lysine 225 mg, methionine 355 mg, phenylalanine 803 mg, threonine 389 mg, valine 614 mg, leucine 1395 mg and isoleucine 508 mg (FAO, 1970).
Loosely tufted, erect, annual grass up to 1.4 m tall, with glabrous stems. Leaves alternate, simple; leaf sheath glabrous, smooth, striate; ligule membranous, rounded, broad, 2–3 mm long; blade linear, tapering upwards, up to 30 cm × 1 cm, glabrous except for some long hairs near the base. Inflorescence a terminal digitate panicle of (2–)4–10(–11) sessile raceme-like primary branches 12–14 cm long. Spikelet up to 2.5 mm stalked, elliptical-lanceolate to oblong, up to 2 mm × 1 mm, acute, glabrous, green to dark brown, 2-flowered; lower glume hyaline, minute; upper glume ovate-oblong, 1–1.5 mm long, hyaline, 3-veined; lower floret sterile, upper floret bisexual; lemma of lower floret 7-veined, lemma of upper floret brownish to black; palea slightly shorter than lemma; stamens 3; ovary superior, with 2 stigmas. Fruit a caryopsis (grain), ellipsoid, 1.5–2 mm × 1 mm.
Digitaria iburua mainly differs from its possible ancestor Digitaria ternata by its glabrous spikelets. Digitaria iburua greatly resembles Digitaria exilis (Kippist) Stapf (fonio). It is called black fonio because of its dark spikelets, but its grain is white.
Black fonio is grown at 400–1300 m altitude in areas with an annual rainfall of 900–1000 mm. It is credited with yielding a crop where fonio fails due to drought. Though it reputedly grows well on poor soils, it is planted on more fertile soils in northern Nigeria.
The 1000-seed weight of black fonio is about 500 g. In northern Nigeria it is usually planted towards the end of June and harvested in November–December. It is frequently grown intercropped with fonio, pearl millet or sorghum. Black fonio is difficult to husk and it is mostly eaten imperfectly cleaned.
Genetic resources and breeding
No germplasm collections or breeding programmes of black fonio seem to exist, but germplasm of 2 landraces (‘Tchibam’ and ‘Tripka’), tentatively identified as Digitaria iburua, has been collected in Togo for the Institut Togolais de Recherche Agronomique (ITRA). Information on the genetic variation within the species and its liability to genetic erosion is not available.
Black fonio is clearly less important than fonio, but is valued as a traditional cereal in some parts of West Africa. Its importance is unlikely to increase, also in view of the difficult husking. Little is known about its ecological requirements, agronomy and potential for genetic improvement, and research in these fields is recommended.
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Correct citation of this article:
Brink, M., 2006. Digitaria iburua Stapf In: Brink, M. & Belay, G. (Editors). PROTA 1: Cereals and pulses/Céréales et légumes secs. [CD-Rom]. PROTA, Wageningen, Netherlands.