Brachiaria humidicola (Rendle) Schweick.

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Graminae

Synonyms

B. dictyoneura (Fig. and De Not.) Stapf.

Common names

Koronivia grass (Fiji), creeping signal grass (southern Africa).

Description

A procumbent stoloniferous perennial with lanceolate leaf blades, three to four racemes with hairy spikelets 3.5-4 mm long (Napper, 1965). It is distinguished from other species of the genus by its creeping habit. The rachis is narrow and angled. The lower glume is three-fourths as long as the spikelet, and conspicuous because it is purple or purple-brown in the upper part, contrasting with the light green colour of the rest of the spikelet. The leaf-blades are flat, and at least 5 mm wide, often more (Chippendall & Crook, 1976).

Distribution

Tropical Africa.

Season of growth

Summer.

Altitude range

1 000-2 000 m.

Rainfall requirements

It is adapted to the wetter zone of Fiji.

Drought tolerance

It has good drought tolerance (CIAT, 1978) and remains green better than other species with better dry-season production in Fiji (Partridge, 1979b).

Soil requirements

While it does well on deep fertile soils, it proved to be well suited to coral rubble soil of high pH in less-shaded old coconut plantations in the Solomon Islands (Gutteridge & Whiteman, 1978).

Ability to spread naturally

Being intensely stoloniferous, it covers the ground well on red soils but is slow to colonize heavy black soils in Fiji.

Land preparation for establishment

A rough ploughing is sufficient to accommodate the vegetative material planted.

Sowing methods

It is usually established vegetatively, small bundles of stolons being planted at spacings of 1-2 m (Roberts, 1970a, b; Partridge, 1979a).

Sowing depth and cover

The cuttings are planted at 15-20 cm with a spade, and covered.

Sowing time and rate

Sow in the wet season (November to March) in the dry zone, and at any time in the wet zone, in Fiji.

Seedling vigour

Good (CIAT, 1978).

Vigour of growth and growth rhythm

It grows well in summer, and flowering does not normally commence till November in Fiji.

Response to defoliation

It will withstand heavy defoliation.

Grazing management

It withstands heavy grazing except in areas where Navua sedge (Cyperus aromaticus) is a threat in Fiji (Partridge, personal communication).

Response to fire

It will not tolerate burning (CIAT, 1978).

Dry-matter and green-matter yields

In Fiji it produced 10 929 kg DM/ha unfertilized and achieved a yield of 34 018 kg/ha with an application of 452 kg N/ha with a linear response to nitrogen up to that peak yield (Roberts, 1970a, b). In 1972 at Sigatoka, Fiji, when fertilized with 450 kg/ha superphosphate, it produced 17 500 kg DM/ha, of which 49 percent was produced in the dry (winter) season (Partridge, 1979a). At CIAT, Quilichao, Colombia, selection 679 yielded 2 500 kg DM/ha during an 18-week period without phosphorus, and over 5 000 kg DM/ha with the application of 50 kg P2O5/ha (CIAT, 1978).

Toxicity

No toxicity has been reported.

Seed yield

In Colombia, Ferguson (1979) obtained 10-50 kg/ha.

Cultivars

Selections are being made at CIAT, Colombia.

Diseases

It is resistant to diseases.

Main attributes

Its strongly stoloniferous habit, with ability to root at the stolon nodes, covers the ground rapidly and competes particularly well with weeds. Its low phosphorus requirement and resistance to spittle bug.

Main deficiencies

Its low seed production.

Optimum temperature for growth

About 32-35°C in Fiji.

Minimum temperature for growth

It has some cool-season productivity (Roberts, 1970a, b).

Response to light

In less-shaded coconut plantations it performs very well (Gutteridge & Whiteman, 1978).

Ability to compete with weeds

It forms a dense, somewhat woody mat layer beneath grazing level and effectively suppresses weeds (Roberts, 1970a, b).

Pests

It has no serious insect pests. It is resistant to spittle bug (Deois incompleta) in the Brazilian humid tropics (Serrão et al., 1979).

Palatability

It is palatable when young, but of low palatability at maximum productivity (Roberts, 1970a, b). Selection 679 has low dry-matter digestibility and low nitrogen content at CIAT, Quilichao, Colombia (CIAT, 1978).

Natural habitat

Valley grassland in moist situations, road verges, and vleis.

Tolerance to flooding

Good, but not as great as Brachiaria mutica.

Fertilizer requirements

It responds well to high nitrogen applications and is much more productive than Batiki blue grass (Ischaemum indicum) (Roberts, 1970a, b). It has excellent tolerance to aluminium (Spain, 1979) and has low phosphorus requirements.

Compatibility with other grasses and legumes

Because of its dense growth it is difficult to establish legumes with it. Sod-seeding siratro and centro into it has had some success if the grass is mown closely, but weed invasion by Mimosa pudica is a problem in Fiji (Roberts, 1970a, b). It combines with Desmodium heterophyllum in Fiji (Partridge, personal communication). In Zimbabwe it combines well with Trifolium semipilosum and Lotononis bainesii (Clatworthy, 1970).

Genetics and reproduction

2n=72 (Fedorov, 1974).

Seed production and harvesting

It is a shy seeder, and this factor alone contributes to its slow spread (Roberts, 1970a, b). The seed also has low viability.

Economics

It is used for grazing in Brazil, Fiji and other parts of the world.

Animal production

Selection 679 was to be subjected to grazing trials at CIAT, Colombia during 1979 and subsequently.

Links for the genus:

Further reading

CIAT, 1978; Clatworthy, 1970.

Value for erosion control

It would prove a very effective grass for erosion control (Chippendall & Crook, 1976).