Brachiaria mutica (Forsk.) Stapf

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Graminae

Synonyms

  • Panicum muticum Forsk.
  • P. purpurascens Raddi.


Common names

Para grass (Africa, Australia, United States), Mauritius signal grass (South Africa), pasto pare and malojilla (South America), gramalote (Peru), parana (Cuba).

Description

A short-culmed, stoloniferous perennial up to 200 cm high with long, hairy leaf-blades about 16 mm wide. Panicle 10-20 cm long with solitary racemose or compound branches and glabrous, acute, irregularly multiseriate spikelets 3-3.5 mm long (Napper, 1965).

Distribution

Tropical areas of Africa and America, now introduced into most tropical countries.

Season of growth

A summer perennial.

Altitude range

Sea-level to 1 000 m.

Rainfall requirements

Adapted to high-rainfall tropical and subtropical conditions, but in protected areas it can persist with rainfall as low as 900 mm per year.

Drought tolerance

It usually tolerates general drought by reason of its specific swampy environment, being maintained by the residual moisture from the wet season.

Soil requirements

It prefers alluvial and hydromorphic soils but will grow on a wide range of moist soil types.

Ability to spread naturally

Under suitable conditions Para grass sends out long stolons and branches bend over and both root at the nodes. It can spread some 5 m in a growing season (Cameron & Kelly, 1970).

Land preparation for establishment

An initial ploughing may be necessary for a rough seed-bed in cleared land. Sprigs can be hand planted in the ashes of burnt wet sclerophyll forest or rain forest, or can be directly planted into swampy land.

Sowing methods

Para grass is usually sown by partly burying sections of the stem in loose, moist earth. Stem cuttings about 25 cm long are planted, preferably as two to three-noded loops at 1-m spacing, or cuttings can be broadcast and disc- harrowed in. Where seed is used, it can be sown in the ashes of a burn or well- prepared seed-bed, or directly into wet areas.

Sowing depth and cover

Sow seed no deeper than 1 cm and roll after seeding.

Sowing time and rate

In spring, summer or late winter, depending on soil moisture, at 2.5-4.5 kg/ha where seed is available.

Number of seeds per kg.

About 1 000 000.

Tolerance to herbicides

Para grass can become troublesome in irrigation ditches, drains and earth tanks. It can be killed by spraying with 2,2-DPA at 2.3 kg of a 740 g AI/kg product (e.g. Dowpon) plus paraquat at 85 ml of a 200 g AI/litre product (e.g. Gramoxone) plus wetting agent at 250 ml per 200 litres of water. Spray till the solution runs off the leaves. Spray when the plant is growing vigorously. Glyphosate at 2 litres of a 360 g AI/litre product (e.g. Roundup) per 200 litres of wafer will also kill it (Tilley, 1977). Undiluted diesel distillate and sodium chlorate at 100 g/litre of water will also kill it (Kleinschmidt & Johnson, 1977).

Seedling vigour

Seedlings are very robust and vigorous.

Response to defoliation

Low grazing and cutting can seriously deplete Para grass stands. Livestock preferentially eat the leaves and young shoots, and if animals are forced to eat the stems the damage to new growing points is severe.

Grazing management

It should not be grazed too closely, and the first grazing should be deferred till the grass is 30-60 cm high and well-established: about 12 months. Regular, controlled light grazing will ensure rapid regrowth (Currie, 1975).

Response to fire

Para grass usually grows in such moist situations that fire is unusual. Burning is not recommended. If the plants survive, fire damage is usually superficial but regrowth is slow (Currie, 1975).

Dry-matter and green-matter yields

Three to four cuttings a season each of 2 5007 500 kg/ha can be obtained. At Laguna, Philippines, Furoc and Javier (1976) obtained 84 300 kg/ha of green matter from an irrigated crop, equivalent to 24 000 kg DM/ha, sufficient to feed eight steers for one year. In Fiji, green weights per hectare vary between 83 000-91 000 kg/ha with a crude protein percentage of 5.5 to 15 percent of the dry matter (Roberts, 1970a, b). At South Johnstone in north Queensland 29 818 kg DM/ha per year were obtained.

Suitability for hay and silage

The waterlogged nature of moist soils growing Para grass prevents the passage of machinery for hay and silage making. In a "cut-and- carry" system, hay and silage can be made. The grass should not be cut too low, as subsequent regrowth will be retarded. It makes good silage with dry-matter losses of 10 percent (Paterson, 1945).

Value as a standover or deferred feed

Para grass is very valuable in this regard, as its environment is such that soil moisture persists well into the dry season so green growth is usually available for livestock at a crucial time.

Toxicity

It is usually non-toxic. One case was reported in 1913 in Queensland as being cyanogenetic (Everist, 1974).

Seed yield

Up to 31 kg/ha.

Cultivars

In Zaire, var. Lopori gives high yields and is recommended for permanent pastures (Risopoulos, 1966). There are no registered cultivars in Australia.

Diseases

It is relatively free of diseases. Coccid bug attack associated with sooty mould fungus (Capnodium sp.) causes damage to young leafy shoots (Cameron & Kelly, 1970). Blast (Piricularia sp.) and sheath blight (Rhizoctonia sp.) occur in Thailand (Vinijsanond, 1978).

Main attributes

A well-adapted grass for growing in swamps and shallow streams in both running water and temporary waterholes, providing grazing in both wet and dry seasons. It is still the best grass for this purpose in the tropics.

Main deficiencies

A pest in irrigation ditches, headlands, drains and earth tanks. When this blockage leads to waterlogging, adjacent crops may be lost. It is a coarse fodder when mature. It does not combine easily with legumes.

Optimum temperature for growth

Mean annual temperature 21C (Russell & Webb, 1976).#

Minimum temperature for growth

15C (Allen & Cowdry, 1961).

Frost tolerance

Para grass is frost sensitive and severely affected by it, but persists well. It will not stand a lower temperature than 8C (Wheeler, 1950).

Latitudinal limits

It extends to about 27S in selected areas. Viable seed was collected at latitude 13S in the Northern Territory of Australia (Wesley-Smith, 1973, Russell & Webb, 1976).

Response to light

It will grow in partial shade but prefers full sunlight.

Ability to compete with weeds

In its natural habitat, Para grass competes successfully with weeds. On Navua plantation in Fiji there is severe competition with Cyperus aromaticus. The Para grass is disc-harrowed to chop the stems and submerge them partly in the mud to encourage more rooting and a heavier population of plants to give more competition.

Maximum germination and quality required for sale

15 percent germinable seed, 40 percent purity in Queensland, Australia.

Pests

Navua sedge (Cyperus aromaticus) infests Para grass pastures in Fiji. Some relief is obtained by chopping the Para grass pastures with a fluted roller, burying more nodes under the mud and thickening the stand.

Palatability

Young Para grass stems and leaves are very palatable. The coarse old stems are eaten only if grazing pressure is applied.

Response to photoperiod

It is a short-day plant (Wang, 1961).

Natural habitat

Swampy places and stream banks.

Tolerance to flooding

Para grass is semi-aquatic and can persist in standing and running water. It inhabits wetter areas than B. humidicola.

Fertilizer requirements

It responds readily to nitrogen (Roberts, 1970a, b). On phosphorus-deficient soils a dressing of 500 kg/ha should be applied prior to planting with subsequent top-dressings of 120-250 kg/ha per year for a few years. Nitrogen applied toward the end of summer or in autumn will give better winter growth (Currie, 1975). It tolerates high aluminium (Spain, 1979)

Compatibility with other grasses and legumes

Para grass generally dominates a sward where conditions are favourable. Legumes suitable to moist conditions such as hetero (Desmodium heterophyllum), puero (Pueraria phaseoloides), centro (Centrosema pubescens) and calopo (Calopogonium mucunoides) can persist for varying periods with it (see Plate 26). If conditions favour the legume and suppress the grass, the mixture can be maintained longer. In north-east Thailand, Para grass sown on a lateritic red earth soil is not vigorous enough to suppress Centrosema pubescens, and a good legume/grass balance is possible.

Genetics and reproduction

Reproduction is usually by vegetative means, though seed production does take place at low latitudes. The chromosome number is 2n=36 (Fedorov, 1974).

Seed production and harvesting

Application of 125 kg/ha of urea at the onset of the wet season significantly increases both the number of reproductive tillers and also the yield of harvestable seed from about 20 kg/ha to over 25 kg/ ha (Currie, 1975), while Grof (1969) increased seed yield from 13 to 31 kg/ha with 112 kg N/ha. Harvest within the week in which general anthesis is completed (Grof, 1969). It can be harvested mechanically by direct heading or it can be hand collected.

Economics

It has been used as a pasture in Australia since its introduction in 1849. It is now used extensively for grazing and cut fodder in most tropical and subtropical countries with adequate rainfall (Cameron & Kelly, 1970).

Animal production

At Palmira Station, Colombia, crossbred Brahman steers grazed Para grass at 2.5 beasts per hectare on unfertilized plots and gained 0.6 kg per head per day. On nearby pastures fertilized with nitrogen and irrigated, daily gains were 0.78 kg per head (Crowder, Chaverra & Lotero, 1970). In alluvial swampy areas it will carry more than three animals per hectare (Currie, 1975). At Parada (north Queensland) Evans (1969), using a Para grass/centro mixture under irrigation, recorded a live-weight gain of 0.96 kg per head per day with shorthorn bullocks.

Value for erosion control

Para grass can be quite useful for stream bank and stream erosion control, and on steep slopes where rainfall and soil permit vigorous growth.

Tolerance to salinity

In south-east Queensland it grows on deep loamy soils overlying saline clays and merges with saline grasses on marine flood plains.

Links:

Links for the genus:

Further reading

Cameron & Kelly, 1970; Currie, 1975.