Prota 1: Cereals and pulses/C้r้ales et l้gumes secs
Journ. Bot. 69: 54 (1931).
2n = 28, 30, 42
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.
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.
Young green leaves of Urochloa mosambicensis typically contain up to 2.5% N, 0.2% P and are 6570% digestible. In the late wet season these values are 1.2%, 0.15% and 5560%, 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.
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, 230 cm ื 320 mm, pale to bright green, more or less hairy. Inflorescence composed of 220 racemes borne on a central axis 315 cm long; racemes (1)29(14) cm long, bearing solitary spikelets on a narrowly winged rachis. Spikelet ovate, 2.55.5 mm ื 1.53 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 34 weeks after the start of the rainy season and continues until growth ceases. Seed matures in 34 weeks. Leaves live for 525 weeks depending mainly on water supply. Plants are often short-lived (34 years). Urochloa mosambicensis is an obligate apomict. It follows the C4 photosynthetic pathway.
In its natural habitat Urochloa mosambicensis occurs up to 1600 m altitude in regions with an average annual rainfall of 4001200(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.
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 11.7 g. Fresh seed has dormancy, which breaks down after 912 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 100300 kg/ha per year have been recorded from Australia. In pastures dry matter yields of 18 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.
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.
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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.