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Urochloa mosambicensis (Hack.) Dandy

Protologue
Journ. Bot. 69: 54 (1931).
Family
Poaceae (Gramineae)
Chromosome number
2n = 28, 30, 42
Vernacular names
Sabi grass, common urochloa, bushveld signal grass (En).
Origin and geographic distribution
Urochloa mosambicensis is distributed from Kenya southwards to South Africa; it has been introduced as a pasture grass into many other tropical countries, including Ghana and Madagascar. It was introduced into Australia in the early 1900s and has become an important grass for the northern Australian beef industry.
Uses
In southern Africa the grain of Urochloa mosambicensis is commonly used as a cereal; the ground grain is made into porridge. Urochloa mosambicensis is a useful, drought-resistant, palatable pasture grass also suitable for hay making. It is planted as a pasture grass in East Africa, southern Africa, Madagascar, India, Sri Lanka and Australia. In South Africa it is sown to improve overgrazed pastures. In India it is used against soil erosion. In Australia it plays a role in mine site rehabilitation.
Properties
Young green leaves of Urochloa mosambicensis typically contain up to 2.5% N, 0.2% P and are 65–70% digestible. In the late wet season these values are 1.2%, 0.15% and 55–60%, respectively. Dry leaves and stems are much lower in quality and typically contain 0.5% N and 0.2% P. Information on the nutritional characteristics of the grain is not available.
Botany
Tufted or stoloniferous perennial grass up to 1.5 m tall; stem (culm) ascending, sometimes rooting at the lower nodes. Leaves alternate, simple and entire; leaf sheath silky pubescent; ligule a ciliate membrane; blade linear, 2–30 cm ื 3–20 mm, pale to bright green, more or less hairy. Inflorescence composed of 2–20 racemes borne on a central axis 3–15 cm long; racemes (1–)2–9(–14) cm long, bearing solitary spikelets on a narrowly winged rachis. Spikelet ovate, 2.5–5.5 mm ื 1.5–3 mm, glabrous or hairy, acuminate, 2-flowered with lower floret male and upper bisexual; lower glume elliptical-oblong, shorter than spikelet, 3-veined, shiny, upper glume as long as the spikelet, 5-veined with cross-veins, granulose to rugulose, with a mucro; lemma acuminate, leathery, 5-veined, with a mucro, palea shorter than lemma; stamens 3; ovary superior, with 2 plumose stigmas. Fruit a strongly flattened caryopsis (grain), pale buff or cream.
Urochloa comprises about 12 species distributed in the Old World tropics, mainly in Africa. It is distinguished from the related Brachiaria by the shape and orientation of the spikelets but the boundary between the two genera is unclear due to a number of intermediate species. It has been proposed that Brachiaria be nearly completely reduced to Urochloa, which would increase the size of Urochloa to about 120 species, with a pantropical distribution. Within Urochloa the species are sometimes difficult to separate. Urochloa mosambicensis is the perennial counterpart of the annual Urochloa trichopus (Hochst.) Stapf, which does not possess dormant buds at the base. The grain of Urochloa brachyura (Hack.) Stapf, distributed in East and southern Africa, is eaten in Namibia; the plant is also grazed by animals.
Seeds of Urochloa mosambicensis germinate early in the wet season and vegetative growth continues until soil water is exhausted. Flowering starts 3–4 weeks after the start of the rainy season and continues until growth ceases. Seed matures in 3–4 weeks. Leaves live for 5–25 weeks depending mainly on water supply. Plants are often short-lived (3–4 years). Urochloa mosambicensis is an obligate apomict. It follows the C4 photosynthetic pathway.
Ecology
In its natural habitat Urochloa mosambicensis occurs up to 1600 m altitude in regions with an average annual rainfall of 400–1200(–1600) mm, in savanna woodland and open grassland, often in disturbed or overgrazed locations (e.g. fallow land, roadsides). It grows in a wide range of soils, but prefers lighter, more fertile soils. In northern Australia it becomes dominant after fires.
Management
The grains of Urochloa mosambicensis are mostly collected from the wild, but sometimes plants are grown in gardens alongside maize. The 1000-seed weight is 1–1.7 g. Fresh seed has dormancy, which breaks down after 9–12 months storage. Dormancy can be broken by hammer-milling, destroying the hard lemma. In India Urochloa mosambicensis is also propagated vegetatively using rooted cuttings. In pastures a seed rate of 4 kg/ha is recommended, or 2 kg/ha when grown intercropped with other pasture plants. Urochloa mosambicensis does well in intercropping with leguminous pasture plants and is commonly grown together with Stylosanthes spp. To obtain the grain, the inflorescences are picked when still slightly green and spread out in the sun to dry. When dry, the grains are easily rubbed from the stalks; they are ground. Grain yields of 100–300 kg/ha per year have been recorded from Australia. In pastures dry matter yields of 1–8 t/ha per year are produced.
Genetic resources and breeding
The largest germplasm collections of Urochloa mosambicensis are held in Australia (Australian Tropical Crops & Forages Genetic Resources Centre, Biloela, Queensland, 73 accessions, mainly from African countries; CSIRO Townsville Division of Tropical Crops and Pastures, Townsville, Queensland, 63 accessions). In Africa 18 accessions are held in South Africa (Grassland Research Centre, Department of Agricultural Development, Pretoria), 7 accessions in Ethiopia (International Livestock Research Institute (ILRI), Addis Ababa) and 7 accessions in Kenya (National Genebank of Kenya, Crop Plant Genetic Resources Centre, KARI, Kikuyu). In view of its wide distribution and abundance, Urochloa mosambicensis is not threatened by genetic erosion.
The collection held in Biloela has been investigated for a range of morphological and agronomical attributes, and considerable variation was found in time to maturity, stolon development, plant height and yield. Cultivars of Urochloa mosambicensis have been registered in Australia, e.g. ‘Nixon’ and ‘Saraji’.
Prospects
Urochloa mosambicensis is a useful wild cereal in southern Africa, but it has more potential as a pasture grass for semi-arid tropical regions. Investigations are needed to assess the nutritional quality of the grains.
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.
• Clayton, W.D., 1989. Gramineae (Paniceae, Isachneae and Arundinelleae). In: Launert, E. & Pope, G.V. (Editors). Flora Zambesiaca. Volume 10, part 3. Flora Zambesiaca Managing Committee, London, United Kingdom. 231 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.
• McIvor, J.G., 1992. Urochloa mosambicensis (Hack.) Dandy. In: ’t Mannetje, L. & Jones, R.M. (Editors). Plant Resources of South-East Asia No 4. Forages. Pudoc Scientific Publishers, Wageningen, Netherlands. pp. 230–231.
• Pengelly, B.C. & Eagles, D.A., 1999. Agronomic variation in a collection of perennial Urochloa spp. and its relationship to site of collection. Genetic Resources Communication 29: 1–13.
Other references
• Bogdan, A.V., 1977. Tropical pasture and fodder plants (grasses and legumes). Longman, London, United Kingdom. 475 pp.
• Clayton, W.D. & Renvoize, S.A., 1982. Gramineae (Part 3). In: Polhill, R.M. (Editor). Flora of Tropical East Africa. A.A. Balkema, Rotterdam, Netherlands. pp. 451–898.
• Gibbs Russell, G.E., Watson, L., Koekemoer, M., Smook, L., Barker, N.P., Anderson, H.M. & Dallwitz, M.J., 1990. Grasses of Southern Africa: an identification manual with keys, descriptions, distributions, classification and automated identification and information retrieval from computerized data. Memoirs of the Botanical Survey of South Africa No 58. National Botanic Gardens / Botanical Research Institute, Pretoria, South Africa. 437 pp.
• Mackay, J.H.E., 1974. Register of Australian herbage plant cultivars. A. Grasses. 15. Urochloa. a. Urochloa mosambicensis (Hack.) Dandy (sabi grass) cv. Nixon (reg. no. A–15a–1). Journal of the Australian Institute of Agricultural Science 40(1): 89–91.
• Prakash, V. & Uniyal, B.P., 1980. Urochloa mosambicensis (Hack.) Dandy (Poaceae) in India. Bulletin of the Botanical Survey of India 22(1–4): 210–212.
• van Wyk, B.E. & Gericke, N., 2000. People’s plants: a guide to useful plants of southern Africa. Briza Publications, Pretoria, South Africa. 351 pp.
• Veldkamp, J.F., 1996. Brachiaria, Urochloa (Gramineae - Paniceae) in Malesia. Blumea 41: 413–437.
• FAO, undated. Grassland Index. [Internet]. FAO, Rome, Italy. http://www.fao.org/ag/AGP/AGPC/doc/GBASE/Default.htm. Accessed July 2005.
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. Urochloa mosambicensis (Hack.) Dandy In: Brink, M. & Belay, G. (Editors). PROTA 1: Cereals and pulses/C้r้ales et l้gumes secs. [CD-Rom]. PROTA, Wageningen, Netherlands.