Urochloa oligotricha


Scientific name

Urochloa oligotricha (Fig. & De Not.) Henrard

Synonyms

Brachiaria bulawayensis (Hackel) Henr.
Eriochloa bolbodes (Steud.) Schweinf. 
Helopus bolbodes Hochst. ex Steud.
Panicum bulawayense Hackel
Panicum bolbodes (Hochst. ex Steud.) Asch. & Schweinf.
Panicum oligotrichum Fig. & De Not.
Urochloa bolbodes (Hochst. ex Steud.) Stapf

Family/tribe

Family: Poaceae (alt. Gramineae) subfamily: Panicoideae tribe: Paniceae.

Common names

perennial signal grass, dubi grass , beesgras.

Morphological description

Tufted perennial, with short rhizomes and variable stolon development (<U. mosambicensis );  foliage 30–60 cm and fertile culms 60–120 cm high, silky tomentose, sometimes bulbous at the base.  Leaf blades linear, 10–40 cm long, 5–20 mm wide.  Inflorescence of (2–) 6–20 racemes spreading, on a finely-hairy axis 5–10 cm long;  racemes 3–10 cm long, bearing mostly paired spikelets on a subtriquetrous rachis, the latter with or without bristles.  Spikelets lanceolate to narrowly ovate, 3.5–6 mm long, glabrous, pubescent or setosely fringed, acuminate;  lower glume lanceolate, 5 (–7)-nerved, membranous to herbaceous, mostly two-thirds to three-quarters the length of the spikelet, without a central tuft of bristles, narrowly obtuse to acute;  upper glume glabrous or pubescent;  lower lemma sometimes with a setose fringe;  upper lemma granulose to rugulose, with a mucro 0.3–1 mm long.  900,000–1.2 million seeds/kg.

Distinguished from U. mosambicensis by the thinner, 5–nerved lower glume and narrower spikelets.

Distribution

Native to:
Africa:  Angola, Botswana, Democratic Republic of Congo (Zaire), Ethiopia, Kenya, Malawi, Namibia, South Africa, Tanzania, Uganda, Zambia, Zimbabwe.
Found in savanna woodland, roadsides and as a weed in old farmland.

Uses/applications

Main application as a rapidly establishing, short or long term pasture ;  not as good as U. mosambicensis for ground cover/erosion control.

Ecology

Soil requirements

Occurs over a range of soil textures from sands to clays, although more commonly on light to medium textured soils of pH (6.0–) 6.5–7.5 (–8.5).  Found in both well and poorly drained soils.

Moisture

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Largely from areas of annual rainfall , (400–) 600–1,000 (–1,500) mm, U. oligotricha is moderately drought tolerant.  Although it is sometimes found in wet areas (not swamps), there is no record of the impact of flooding.

Temperature

U. oligotricha occurs naturally from about 14ºN (Sudan) to 25ºS (South Africa), and from 300–2,000 m asl, areas mostly with an average annual temperature ±20ºC (>27ºC in the Sudan).  It makes most growth in summer, but responds to out-of-season rains.  Leaves are burnt off by frost, but plants recover with onset of warmer, moist conditions.

Light

It can grow under light to moderate shade.

Reproductive development

As with U. mosambicensis , most accessions appear to be day neutral, flowering through much of the growing season.  However, some mature earlier than others suggesting other factors such as temperature may be involved.

Defoliation

It is selectively grazed and can be grazed out in more intensive systems.

Fire

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Density is favoured by annual burning.

Agronomy

Establishment

Seed dormancy does not seem to be as pronounced as it is in U. mosambicensis U. oligotricha is best established by drilling or broadcasting seed at 1–3 kg/ha into a well-prepared seedbed.  It is preferable to roll afterwards.  Seedlings establish quickly, so establishment is also possible into a “rough” seedbed.

Fertiliser

It responds well to nitrogen on less fertile soils.  Other nutrients, particularly P and K, should be monitored and maintained as required.  Despite growing naturally on soils with low available phosphorus, large responses to applied P have been measured.  On very low fertility soils, applications of up to 30–60 kg/ha of P may be necessary, depending on genotype, to maximise production.  A critical P level in the tissue of 0.2–0.3 % of the DM is proposed.

Compatibility (with other species)

U. oligotricha is not an aggressive species and can be grown successfully with legumes and other grasses.

Companion species

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Pests and diseases

No record of pests or diseases available.

Ability to spread

It primarily spreads by seed, less readily than U. mosambicensis , and more so than Cenchrus ciliaris .

Weed potential

U. oligotricha does not appear to have the same weediness characteristics as U. mosambicensis and U. panicoides.

Feeding value

Nutritive value

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As with U. mosambicensis , crude protein content of the first fully expanded green leaf on a plant can fall from about 15% to a little over 4% in 4 weeks, with P levels showing a similar rate of decline.  P levels in tops can vary from 0.15–0.65% depending on P fertility of the soil.

Palatability/acceptability

Very palatable.

Toxicity

No record of toxicity.

Production potential

Dry matter

In the seasonally dry tropics, U. oligotricha has produced DM yields of 6 t/ha compared with 16 t/ha from Brachiaria decumbens , and 1.5–4 t/ha when U. mosambicensis produced 5–7 t/ha.  Green matter yields have varied from 58–67 t/ha (equivalent to 13–15 t/ha DM) depending on cutting frequency.

Animal production

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No information available.

Genetics/breeding

Apomictic, 2n = 36.

Seed production

No information available.

Herbicide effects

No information available.

Strengths

  • Rapid establishment.
  • Fast regrowth.
  • Very palatable.
  • Widely adapted (including alkaline soils).
  • Compatible with legumes.

Limitations

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  • Intolerant of heavy grazing.
  • May not suit cracking clays.

Other comments

  

Selected references

Burt, R.L., Sinclair, D.F., Harrison, P., Pengelly, B.C. and Williams, W.T. (1980) Preliminary agronomic evaluation of some perennial Urochloa species over a range of environments. Australian Journal of Experimental Agriculture and Animal Husbandry, 20, 439–446.
Burt, R.L., Williams, W.T., Gillard, P. and Pengelly, B.C. (1980) Variation within and between some perennial Urochloa species. Australian Journal of Botany, 28, 343–356.
Clayton, W.D. and Renvoize, S.A. (1982) Gramineae (Part 3). In: Polhill, R.M. (ed.) Flora of tropical East Africa A.A. Balkema on behalf of the East African Governments, Rotterdam, Netherlands.
McIvor, J.G. (1984) Effects of phosphorus and superphosphate on the growth of Urochloa species. Australian Journal Of Experimental Agriculture And Animal Husbandry, 24, 571–578.
McIvor, J.G. (1984) Leaf growth and senescence in Urochloa mosambicensis and U. oligotricha in a seasonally dry tropical environment. Australian Journal of Agricultural Research, 35, 177–187.
Pengelly, B.C.and Eagles, D.A. (1999) Agronomic variation in a collection of perennial Urochloa spp. and its relationship to site of collection. Genetic Resources Communication No. 29. CSIRO Tropical Agriculture, St Lucia, Qld Australia. ISBN 0 643 05912 1.
Whiteman, P.C. and Gillard, P. (1971) Species of Urochloa as pasture plants. Herbage Abstracts, 41, 351–357.

Internet links

Cultivars

Cultivars

Country/date released

Details

None released to date.      

Promising accessions

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Promising accessions

Country

Details

CPI 47122 Queensland, Australia From Outjo, Namibia (20ºS, 1,200 m asl, rainfall 500 mm).  Tall tussocky type with few or no stolons, performing well over a range of sites in the seasonally dry tropics.
CPI 60122 Queensland, Australia From Zambia (17ºS, 1,240 m asl, rainfall 700 mm).  Tall type with few stolons.  Performed well in the sub-humid subtropics.
CPI 60123 Queensland, Australia From Zimbabwe (18ºS, 790 m asl, rainfall 550 mm).  Medium type with stolons.  Performed well in the sub-humid subtropics.