Cynodon plectostachyus (K. Schum.) Pilger

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Graminae

Common names

Naivasha star grass (eastern Africa), estrella (South America), Bermuda mejorado, Hawaiiano (Costa Rica).

Description

A large, robust, non-rhizomatous grass. True C. plectostachyus is a diploid which can easily be identified by the small glumes, rarely as long as one- third of the spikelet; soft foliage; racemes in two or more whorls and arching stolon internodes (Harlan, de Wet & Rawal, 1970).

Distribution

C. plectostachyus has a fairly restricted natural distribution along the Rift Valley through Ethiopia, Kenya, northern Uganda and northern Tanzania.

Season of growth

Summer.

Altitude range

Sea-level to 2 000 m.

Rainfall requirements

It is adapted to semi-arid areas with rainfalls from 500-875 mm.

Drought tolerance

Very good.

Soil requirements

It has a wide range of tolerance from sandy loams to alluvial silts and clays, and black cracking clay soils, but prefers soil of high fertility.

Ability to spread naturally

Excellent­under good conditions its stoloniferous habit allows it to spread rapidly.

Land preparation for establishment

Full land preparation is required for establishment from seed.

Sowing methods

It can be established from seed or by splits dug into the soil, this latter requiring less land preparation.

Sowing depth and cover

Seed should be surface sown and lightly covered and rolled.

Sowing time and rate

In the wet season at 6.5 kg/ha.

Number of seeds per kg.

25-40 million florets with one caryopsis (Bogdan & Pratt, 1967).

Seed treatment before planting

Treat with an insecticide.

Seedling vigour

Good.

Response to defoliation

Excellent. It can stand heavy grazing.

Grazing management

It should be grazed fairly heavily and top-dressed with nitrogen as required.

Response to fire

It survives fire very well and quickly responds to subsequent rain.

Dry-matter and green-matter yields

Strickland (1976-77) recorded a range of dry-matter yields of 1 300 kg/ha per month in summer to 300-1 100 kg/ha per month in winter from three accessions tested at Samford, Queensland. In Nigeria, Moore (1965) cut 3 300 kg/ha of C. plectostachyus/centro hay from cutting at 5-10 cm at eight-week intervals. At Gualaca, Panama it produced 6 000 kg DM/ha without fertilizer and 32 000 kg DM/ha with 600 kg N/ha in a rainfall regime of 3 997 mm a year (Rattray, 1973).

Suitability for hay and silage

It makes quite good hay, and with the addition of 10 percent molasses makes good silage (Medling, 1972).

Value as a standover or deferred feed

It makes quite good deferred grazing.

Toxicity

No toxicity can be attributed to this grass in Queensland (Everist, 1974).

Seed yield

25 kg/ha from one harvest at Samford, Queensland (Strickland, 1976- 77).

Main attributes

Its rapid colonization of bare land and invasion of overgrazed land.

Main deficiencies

It may become a little aggressive in cultivations.

Frost tolerance

It survives frost.

Response to light

It prefers to grow in full sunlight.

Ability to compete with weeds

Excellent.

Palatability

It is extremely palatable.

Chemical analysis and digestibility

In Costa Rica analysis of material at floral initiation revealed 14.98 percent crude protein, 26.20 percent crude fibre, 37.22 percent nitrogen-free extract, 1.93 percent ether extract, and 9.67 percent ash in the dry matter on a 10 percent moisture basis (Gonzalez & Pacheco, 1970). At Gualaca, Panama, it contained 20-25 percent dry matter in the wet season and 47 percent dry matter in the dry season (Rattray, 1973).

Natural habitat

Dry lake beds.

Tolerance to flooding

Tolerates temporary flooding.

Fertilizer requirements

The optimum phosphorus content of the dry matter for growth was determined by Falade (1975) as 0.305. It responds well to nitrogen.

Compatibility with other grasses and legumes

It tends to form a monospecific sward, but will grow with Medicago species, Trifolium semipilosum and Lotononis bainesii (Clatworthy, 1970).

Genetics and reproduction

A diploid­2n=18 (Fedorov, 1974). Crossbreeding studies have shown it to be completely isolated genetically (Harlan, de Wet & Rawal, 1970).

Animal production

Because of taxonomic confusion, until recently the literature references to the role of C. plectostachyus may actually refer to other species. It is, however, an excellent grazing grass and one which stabilizes soil against wind and water erosion. In Zimbabwe, C. plectostachyus (?) pastures fertilized with 270 kg nitrogen and 38 kg phosphorus per hectare gave a liveweight gain of 830 kg/ha from the grazing of 12.4 heifers per hectare (Rodel, 1970).

Further reading

Harlan, de Wet & Rawal, 1970.

Value for erosion control

Excellent. It has been used on the black cracking clay soils on sloping cultivated land on the Darling Downs, Queensland, with success.

Tolerance to salinity

It is tolerant to alkaline soils and is always found in what appear to be alkaline areas in Kenya.