Brachiaria ruziziensis


Scientific name

Brachiaria ruziziensis R. Germ. and C.M. Evrard

Synonyms

Urochloa ruziziensis (R. Germ. and C.M. Evrard) Crins

Family/tribe

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

Common names

ruzi grass, Congo grass, Congo signal grass, prostrate signal grass (English);  Congo señal, gambutera, Kenia, pasto Congo, pasto ruzi (Spanish);  capim Congo, ruziziensis (Portuguese).

Morphological description

A tufted, creeping perennial with short rhizomes forming a dense leafy cover.  Culms arise from many-noded creeping shoots and short rhizomes, growing to a height of 1.5 m when flowering.  Leaves are soft but hairy, up to 25 cm long and 15 mm wide.  Inflorescence consists of 3–9 relatively long racemes (4–10 cm), bearing spikelets in 1 or 2 rows on one side of a broad, flattened and winged rachis.  Spikelets hairy, 5 mm long.  Seed weight 250,000/kg.

B. ruziziensis is very closely related to B. decumbens , being differentiated morphologically on rachis shape, which is subfoliolate and 2–3.5 mm wide in the former and flat and 1–1.7 mm wide in the latter, and on the position of the lower glume, which is 0.5–1 mm distant from the rest of the spikelet in the former and very close to the upper glume in the latter.

Distribution

Native to:
Africa:  Burundi, Rwanda, eastern Zaire.
Occurs in grasslands and disturbed areas.

Naturalised throughout the humid tropics.

Uses/applications

Permanent or semi-permanent pasture for grazing or for cutting for green feed and conservation .  Also planted for grazing under coconut plantations.

Ecology

Soil requirements

Ruzi grass requires light to loam soils of moderately high fertility (pH 5.0–6.8) and cannot tolerate strongly acid conditions.

Moisture

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Ruzi is a grass for the lowlands and up to 2,000 m in the humid tropics, with a minimum of 1,200 mm AAR .  However, it can tolerate a dry season of 4 months but will die out in extended dry conditions.  Having poor tolerance to flooding, it thrives best on well-drained soils.

Temperature

Warm season growth (optimum growth at 33/28ºC day/night);  minimum night temperature of 19ºC with no frost tolerance .  It is killed by heavy frost and regrowth is very slow after light frosts.

Light

Ruzi has moderate shade tolerance and is grown under coconut plantations.

Reproductive development

Flowers into shortening days, mid-autumn in northern Queensland, Australia (18°S).

Defoliation

It can stand moderately heavy grazing and requires high levels of fertilising to persist under frequent cutting.

Fire

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Ruzi will recover after a fire, but burning is not recommended.

Agronomy

Establishment

Ruzi can be established from seed, which is often cheap but needs to be stored for at least 6 months after harvest.  Broadcast seed at 2.5–10 kg/ha (depending on seed quality) onto a well-prepared seedbed and lightly cover.  Should not be sown deeper than 2 cm.  Infertile soils should be fertilised to supply N, P and K prior to planting.  Seedling growth is vigorous.
Alternatively, ruzi grass can be established vegetatively from stem cuttings with rooting nodes.

Fertiliser

Ruzi demands high fertility soils and adequate fertiliser to persist under grazing or cutting.

Compatibility (with other species)

Under light grazing, ruzi forms a dense cover and competes with weeds.  The sward opens under heavier grazing, allowing broad-leaf weeds to establish and legumes to persist.  It will combine with a range of twining, erect and shrub legumes.

Companion species

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Pests and diseases

Ruzi is severely attacked by spittlebug (Aeneolamia spp., Deois spp. and Zulia spp.) in tropical America.
Leaf is attacked by foliar blight (Rhizoctonia solani) in tropical America.  Seed heads are attacked by a fungus (Sphacelia spp.) in Zaire.

Ability to spread

Ruzi spreads relatively slowly in existing vegetation by stolons and seed drop.  Spread is more rapid where a clean seedbed is provided and soil fertility is sufficiently high.

Weed potential

Unlikely to become a weed of importance due to its relatively slow spread and high fertility requirements, but has potential to become a minor weed.

Feeding value

Nutritive value

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Good nutritive value - better than most other Brachiaria spp.with CP commonly 7–13%, and up to 20%, and digestibility 55–75%.  For ruzi grass hay cut 45 days after seeding in northeast Thailand, the IVDMD, crude fibre, NDF and ME concentrations were 61%, 80.5%, 72.8% and 7.9 MJ/kg, respectively.

Palatability/acceptability

Very palatable.  Selective, heavy grazing pressure and the need for high soil fertility can result in the loss of ruzi grass .

Toxicity

Photosensitization may occur and some references suggest that ruzi grass should not be fed to sheep, goats or young cattle.

Production potential

Dry matter

Less productive than B. decumbens in Australia and South America although yields have exceeded 20 t/ha/year with high rates of nitrogen.  In Sri Lanka, DM yields of 16.8, 22.0 and 25.6 t/ha/year were achieved with N applications of 112, 224 and 366 kg/ha, respectively.  On an oxisol at Coronel Pacheco, Brazil, ruzi grass produced 6.0 t/ha DM without added fertiliser and 12.0 t/ha with 150 kg/ha N fertiliser.

Animal production

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Liveweight gains have exceeded 1,000 kg/ha/year on pastures of ruzi with legumes, and over 1,500 kg/ha/yr with 200 kg/ha N fertiliser.  Steers grazing B. ruziziensis on Brazilian savannas at 2 head/ha gained 285 kg/ha/year.

Genetics/breeding

Diploid;  reproduction is sexual with a high degree of cross-pollination.  Breeding programs are related to the ability of a tetraploid form of B. ruziziensis to confer sexual reproduction ability to interspecific Brachiaria hybrids involving the tetraploid , apomictic B. decumbens /B. brizantha complex (see fact sheet on Brachiaria hybrids).  Typical chromosome number, 2n = 18.  Also tetraploid , 2n = 4x = 38.

Seed production

Seed production is excellent.  Yields of 125–200 kg/ha pure seed have been achieved by combine harvesting, and up to 700 kg/ha seed has been harvested by ground sweeping.  Head emergence is relatively uniform, supporting combine harvesting or sweating.  In Thailand, hand-harvested seed heads are stacked about 1 m deep and allowed to sweat for about 3 days.  The heads are turned daily to facilitate the separation of seed from the head and to prevent overheating.  Alternatively, the “living sheath” method is used, where heads are tied together in groups and effectively sweated in the field for 1–2 weeks before harvest.  The grouped seed heads are shaken into a large net every 2–3 days until all seed is collected.
Main countries of seed production are Brazil and Thailand.
Seed has a high percentage of dormancy following harvest (<20% germination).  Primary dormancy is physiological, whilst long-term dormancy is mechanical, caused by a restriction of the seed coat.  Dormancy may be broken by 6–9 months storage or by acid scarification .

Herbicide effects

No information available.

Strengths

  • Palatable and good quality.
  • High seed yields.
  • Rapid establishment from seed or cuttings.

Limitations

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  • Needs fertile, well drained soil.
  • Lower DM production compared with B. decumbens .
  • Poor persistence on infertile and/or poorly drained soils.
  • Poor dry season growth.
  • Very susceptible to spittlebug.

Other comments

Ruzi grass is generally less popular than B. decumbens as a forage species because it is not productive on acid-infertile soils, is spittlebug susceptible and produces less DM than B. decumbens .

Selected references

Hare, M.D. and Chaisang Phaikew (1997) Forage Seed production in northeast Thailand. In: Loch, D.S. and Ferguson, J.E. (eds) Forage seed production 2, Tropical and subtropical species. pp. 435–443. (CABI Publishing).
Lenné, J.M. and Trutmann, P. (eds) (1994) Diseases of Tropical Pasture Plants. (CABI, Wallingford, UK).
Miles, J.W., Maass, B.L. and do Valle, C.B. (eds) (1996) Brachiaria: Biology, Agronomy and Improvement. CIAT, Cali, Colombia.
Schultze-Kraft, R and Teitzel, J.K. (1992) Brachiaria ruziziensis Germain & Evrard. In: ‘t Mannetje, L. and Jones, R.M. (eds) Plant Resources of South-East Asia No. 4. Forages. pp. 65–67. (Pudoc Scientific Publishers, Wageningen, the Netherlands).

Internet links

Cultivars

Cultivars

Country/date released

Details

‘Kennedy’
Ruzi
(CPI 30231, CIAT 605, BRA 000281, ILCA 16692)
Australia
Thailand
‘Kennedy’ performs well on the wet tropical coast of Queensland.  Seed holds better in the head than signal grass (B. decumbens ) and high seed yields are obtained.  Seed is currently produced in northeast Thailand and sold throughout southeast Asia as “Ruzi”.

Promising accessions

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Promising accessions

Country

Details

None reported.