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Digitaria iburua Stapf

Protologue
Bull. Misc. Inform. Kew 1915: 382 (1915).
Family
Poaceae (Gramineae)
Chromosome number
2n = 54
Vernacular names
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.
Uses
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’).
Properties
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).
Botany
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.
Ecology
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.
Management
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.
Prospects
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.
Major references
• Burkill, H.M., 1994. The useful plants of West Tropical Africa. 2nd Edition. Volume 2, Families E–I. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 636 pp.
• Haq, N. & Dania Ogbe, F., 1995. Fonio (Digitaria exilis and D. iburua). In: Williams, J.T. (Editor). Cereals and pseudocereals. Chapman and Hall, London, United Kingdom. pp. 225–245.
• Hilu, K.W., M’Ribu, K., Liang, H. & Mandelbaum, C., 1997. Fonio millets: ethnobotany, genetic diversity and evolution. South African Journal of Botany 63(4): 185–190.
• Portères, R., 1976. African cereals: Eleusine, fonio, black fonio, teff, Brachiaria, paspalum, Pennisetum, and African rice. In: Harlan, J.R., de Wet, J.M.J. & Stemler, A.B.L. (Editors). Origins of African plant domestication. Mouton Publishers, The Hague, Netherlands. pp. 409–452.
• van der Zon, A.P.M., 1992. Graminées du Cameroun. Volume 2, Flore. Wageningen Agricultural University Papers 92–1. Wageningen Agricultural University, Wageningen, Netherlands. 557 pp.
Other references
• Adoukonou-Sagbadja, A., Dansi, A., Vodouhé, R. & Akpagana, K., 2004. Collecting fonio (Digitaria exilis Kipp. Stapf, D. iburua) landraces in Togo. Plant Genetic Resources Newsletter 139: 59–63.
• Busson, F., 1965. Plantes alimentaires de l’ouest Africain: étude botanique, biologique et chimique. Leconte, Marseille, France. 568 pp.
• FAO, 1970. Amino-acid content of foods and biological data on proteins. FAO Nutrition Studies No 24, Rome, Italy. 285 pp.
• Hanelt, P. & Institute of Plant Genetics and Crop Plant Research (Editors), 2001. Mansfeld’s encyclopedia of agricultural and horticultural crops (except ornamentals). 1st English edition. Springer Verlag, Berlin, Germany. 3645 pp.
• Jideani, I.A., 1999. Traditional and possible technological uses of Digitaria exilis (acha) and Digitaria iburua (iburu): a review. Plant Foods for Human Nutrition 54: 363–374.
• Leung, W.-T.W., Busson, F. & Jardin, C., 1968. Food composition table for use in Africa. FAO, Rome, Italy. 306 pp.
• National Research Council, 1996. Lost crops of Africa. Volume 1: grains. National Academy Press, Washington D.C., United States. 383 pp.
• Prasada Rao, K.E. & de Wet, J.M.J., 1997. Small millets. In: Fuccillo, D., Sears, L. & Stapleton, P. (Editors). Biodiversity in trust: conservation and use of plant genetic resources in CGIAR Centres. Cambridge University Press, Cambridge, United Kingdom. pp. 259–272.
• Stapf, O., 1917–1934. Gramineae. In: Prain, D. (Editor). Flora of tropical Africa. Volume 9. L. Reeve & Co., Ashford, United Kingdom. 1100 pp.
• van der Hoek, H.N. & Jansen, P.C.M., 1996. Minor cereals. In: Grubben, G.J.H. & Partohardjono, S. (Editors). Plant Resources of SouthEast Asia No 10. Cereals. Backhuys Publishers, Leiden, Netherlands. pp. 150–156.
Author(s)
M. Brink
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands


Editors
M. Brink
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
G. Belay
Ethiopian Agricultural Research Organization, Debre Zeit Center, P.O. Box 32, Debre Zeit, Ethiopia
Associate editors
J.M.J. de Wet
Department of Crop Sciences, Urbana-Champaign, Turner Hall, 1102 South Goodwin Avenue, Urbana, IL 61801, United States
O.T. Edje
Faculty of Agriculture, University of Swaziland, P.O. Luyengo, Luyengo, Swaziland
E. Westphal
Ritzema Bosweg 13, 6706 BB Wageningen, Netherlands
General editors
R.H.M.J. Lemmens
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
L.P.A. Oyen
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
Photo editor
A. de Ruijter
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

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.