Cynodon dactylon (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Cynodon dactylon (L.) Pers.

Protologue: Syn. Pl. 1 : 85 (1805).

Family: Gramineae

Chromosome number: 2n= 18, 36

Synonyms

Panicum dactylon L. (1753), Cynodon glabratus Steudel (1854), C. polevansii Stent (1927).

Vernacular names

• Bermuda grass (Am). Couch grass (En). Chiendent dactyle (Fr)
• Indonesia: jukut kakawatan, gigirinling (Sundanese), sukit grinting (Javanese)
• Malaysia: rumput minyak
• Philippines: kawad-kawad (Tagalog), kapot-kapot (Visaya), bakbaka (Ilokano)
• Burma: mye-sa-myet
• Cambodia: smao anchien
• Laos: hnha:z ph'è:d
• Thailand: ya-phraek
• Vietnam: cò' chi', co'ô_g.

Origin and geographic distribution

Bermuda grass is thought to originate from Africa and South and South-East Asia but it has been introduced to all tropical and subtropical regions of the world and has been found to survive at 50°N in Europe and to 4000 m elevation in the Himalayas. It is also found on islands in the Pacific, Atlantic and Indian Oceans.

Uses

Bermuda grass is grazed by ruminants, used in cut-and-carry systems, to control erosion, and as a turf grass. In the United States improved hybrids are also cut for hay. Worldwide it is also a serious weed in maize, cotton, sugar cane, vineyards and plantation crops.

Properties

In vitro digestibility of 5-week-old forage of 500 introductions, uniformly managed, ranged from 40-69%. Nitrogen concentrations of adequately fertilized Bermuda grass range from 2-3%, whereas inadequately fertilized grass or old material may only contain 0.5-1.5% N. It contains low levels of prussic acid, but toxicity symptoms in animals are very rare. There are 3000-4000 seeds/g.

Botany

A stoloniferous, prostrate, sward-forming perennial herb with underground rhizomes penetrating the soil to a depth of 1 m or more. Culms 8-40 cm tall (rarely taller) and 0.5-1 mm in diameter. Leaf-blade linear-lanceolate, 1-16 cm × 2-5 mm, glaucous, glabrous or hairy on upper surface, midrib prominent with two primary and 8-9 secondary nerves on either side; leaf-sheath up to 15 mm long, smooth, hairy or glabrous; ligule a conspicuous ring of white hairs. Flowering stems erect, terminated by 3-6 slender radiating 1-sided racemes 1.5-10 cm long arranged in 1 (rarely 2) whorls; spikelets 2-3 mm long, in two rows tightly appressed to one side of the rachis; glumes 1-nerved, the upper ½-¾ as long as the spikelet; lemma silky pubescent on the keel; palea glabrous. Caryopsis ovoid, 1.5 mm long, yellow to reddish.

Six botanical varieties have been recognized; var. dactylon is distributed worldwide, the other 5 varieties have a limited distribution in Africa and Afghanistan. Improved hybrid cultivars developed in the United States for higher DM yield and improved DM digestibility include "Coastal", "Coastcross-1", "Tifton 78", "Tifton 68", "Hardie", "Oklan", and "Brazos".

Ecology

Bermuda grass grows best where mean daily temperatures are above 24 °C. Temperatures of -2 to -3 °C usually kill leaves and stems back to the ground but rhizomes survive these temperatures and regrowth is rapid in spring. It is deep-rooted and drought-tolerant. It grows best on well-drained soils, but will tolerate long periods of flooding. It will tolerate a broad soil pH range, but grows best with a soil pH above 5.5. It also tolerates low fertility, but it is intolerant of shade.

Agronomy

Bermuda grass can be propagated by planting either seeds or stolons. Good stands can be obtained by planting 5-10 kg/ha hulled seed but higher rates can be used for rapid sward development. Improved hybrid Bermuda grass can only be vegetatively propagated. Plantings of fresh vegetative material should be made in moist soil followed by a roller to compact the soil. A small nursery for vegetatively planting larger areas can easily be established from one or a few vegetative sprigs or stolons.

With adequate fertilization, improved hybrid Bermuda grasses will produce twice as much forage as common types. A minimum of 10 kg/ha of N per month of growth is needed for moderate to high productivity but Bermuda grass, especially the improved hybrids, will respond to rates of up to 60 kg/ha N per month of growth. "Coastal" Bermuda grass at Georgia, United States, produced 1.8, 4.7, and 7.2 t/ha DM with 1.1, 1.2 and 1.3% N when fertilized with 0, 52, and 112 kg/ha N, respectively. Common Bermuda grass could be expected to yield significantly less DM. Low-growing legumes can be grown with Bermuda grass, which improves forage quality and provides some of the N requirements of the grass. Applications of lime may be needed to bring soil pH to 5.5.

Rust and Helminthosporium leaf-spot are the major diseases on common Bermuda grass. The improved hybrids are resistant to these diseases. Armyworm (Spodoptera frugiperda) and spittlebug (Prosapia bicinata) are the major insects that attack Bermuda grass. Adequate fertilization and defoliation that allows less than 8 cm growth to accumulate will help control pests. Burning dead top growth after frosting or after a dormant stage will help control spittlebug and the diseases.

Bermuda grass should be cut for hay or silage when it is 30-40 cm tall or after every 4-6 weeks growth. It can be grazed year-round if not dormant due to frost or drought. A stubble height of 5-10 cm should be maintained under grazing or left if cut for hay. Bermuda grass is best utilized by grazing. It can also be stored as hay after drying, or green-chopped and fed directly to animals, or made into silage.

Genetic resources and breeding

Active breeding programmes (each with over 500 introduced accessions) to improve Bermuda grass are located in Stillwater, Oklahoma and Tifton, Georgia, United States. C. dactylon is highly variable and present collections do not adequately represent the species. Major breeding objectives include increased yield and digestibility, pest resistance, and improved cold tolerance.

Prospects

Much opportunity exists for genetic improvement in yield, pest resistance, and quality. Proper fertilization and management and use of current improved cultivars would have major impact on improving animal nutrition and soil conservation.

Literature

• Burton, G.W. & Hanna, W.W., 1985. Bermuda grass. In: Heath, M.E., Barnes, R.F. & Metcalfe, D.S. (Editors): Forages. Iowa State University Press. Ames, Iowa, United States. pp. 247-254.
• Clayton, W.D. & Harlan, J.R., 1970. The genus Cynodon L.C. Rich. in tropical Africa. Kew Bulletin 24: 185-189.
• de Wet, J.M.J. & Harlan, J.R., 1970. Biosystematics of Cynodon L.C. Rich. (Gramineae). Taxon 19: 565-569.
• Harlan, J.R., 1970. Cynodon species and their value for grazing and hay. Herbage Abstracts 40: 233-238.
• Harlan, J.R., de Wet, J.M.J., Huffine, W.W. & Deakin, J.R., 1970. A guide to the species of Cynodon (Gramineae). Bulletin B-673, Oklahoma State University Agricultural Experiment Station, Stillwater, Oklahoma, United States. 37 pp.
• Skerman, P.J. & Riveros, F., 1990. Tropical grasses. FAO, Rome. pp. 310-315.

Authors

W.W. Hanna