Cynodon nlemfuensis (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Cynodon nlemfuensis Vanderyst

Protologue: Bull. Agric. Congo Belge 13: 342 (1922), (11: 121 (1920), provisional name C. lemfuensis ).

Family: Gramineae

Chromosome number: 2n= 18, 36

Vernacular names

• Stargrass, African stargrass (En, Am)
• Philippines: kolatay (Tagalog), rukut-dukut (Visaya), galud-galud (Ilokano)
• Thailand: ya-sata.

Origin and geographic distribution

Stargrass occurs naturally in East and Central Africa, from Ethiopia and Sudan through Zaire to Malawi and Angola. In other parts of the tropics, including South-East Asia, it has been introduced as a fodder grass.

Uses

Stargrass is grazed by ruminants, and used in cut-and-carry systems and to control erosion.

Properties

Nitrogen concentration and DM digestibility of improved selections range from 1-2% N and 40-70%, respectively. Most stargrass has medium to high levels of prussic acid, which is increased with high nitrogen fertilization. However, only few reports of livestock death due to prussic acid poisoning have been reported.

Botany

A stoloniferous sward-forming perennial without rhizomes; stolons stout, woody, lying flat on the ground; culms robust to fairly slender, 30-60 cm high and 1-3 mm in diameter at the base. Leaf-blade flat, linear-lanceolate, 5-16 cm × 2-6 mm, thin and green or rather stiff and glaucous, scaberulous, with or without scattered hairs; ligule a scarious rim 0.3 mm long. Inflorescence of 4-13 digitate 1-sided spikes, usually in 1, sometimes in 2 whorls; spikes 4-10 cm long; spikelets 2-3 mm long, green or purplish-green, 1-flowered, strongly laterally compressed, imbricate in 2 rows, awnless; glumes 2, 1-3 mm long; lemma silky pubescent to softly ciliate on the keel; palea glabrous. Caryopsis ellipsoid, laterally compressed.

Two varieties have been distinguished, but since they intergrade, distinction is often impossible and thus questionable:

• var. nlemfuensis : culm 1-1.5 mm in diameter; leaf-blade 2-5 mm wide; spikes of 1 inflorescence 4-9, each 4-7 cm long.

• var. robustus Clayton & Harlan: culm 2-3 mm in diameter; leaf-blade 5-6 mm wide; spikes of 1 inflorescence 6-13, each 6-10 cm long; a more robust plant than var. nlemfuensis .

C. nlemfuensis much resembles C. dactylon (L.) Pers., the main difference being the absence of underground rhizomes and the lack of hardiness.

Stargrass grows vigorously and roots at nodes as it spreads. Some genotypes have a bunch-habit type of growth, even though they spread by stolons.

Improved cultivars include: "Florico", "Florona", "Ona", and "Costa Rica".

Ecology

Productivity and persistence of stargrass are limited to lower elevations or where temperatures do not fall below -4 °C, as growth rapidly ceases with low temperatures. In its area of origin it occurs up to 2300 m altitude. It does not tolerate long periods of flooding. It grows on many soil types but does best on moist, well-drained soils. It will tolerate a broad soil pH range but best growth is made on soils with a pH above 5.5.

Agronomy

Improved selections of stargrass are sterile or almost sterile. It can be propagated by planting stolons or stem pieces. 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.

Fertilizer will need to be added to most soils to obtain high DM yields. With adequate fertilization, selected stargrasses will produce more than twice as much forage as common types. A minimum of 10 kg/ha N per month of growth is needed for moderate to high productivity, but stargrass (especially the improved selections) will respond to higher rates. Low-growing legumes can be grown with stargrass 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 of common stargrass. Foliar blight ( Rhizoctonia solani ) has been observed on some of the selected cultivars. Armyworm ( Spodoptera frugiperda ) and spittlebug ( Prosapia bicinata ) are the major insect pests. Adequate fertilization and defoliation that allows less than 15 cm growth to accumulate will help control pests. Burning dead top growth if grass is frosted or after a dormant stage will help control spittlebug and the diseases.

Stargrass 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 temperatures and rainfall are favourable. Overgrazing will decrease stands. A stubble height of 15-25 cm should be maintained under grazing or cutting. Dry matter yields of improved selections vary with climate and soil fertility but are at least twice the yield of local or common types. Stargrass is best utilized by grazing. It can also be stored as hay after drying.

Genetic resources and breeding

Individual researchers around the world have a few accessions. C. nlemfuensis is extremely variable and systematic germplasm collection and maintenance is needed. Isolated improvement programmes have emphasized selection for higher dry matter yield and digestibility among introduced accessions.

Prospects

Much opportunity still exists for genetic improvement in yield and quality. Hybrids need to be produced and evaluated. Proper fertilization and management and wider use of current improved cultivars could have major impact on improving animal nutrition and for soil conservation purposes.

Literature

• 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., Huffinae, 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. 37 pp.
• Mislevy, P., Brown, W.F., Caro-Costas, R., Vicente-Chandler, J., Dunavin, L.S., Hall, D.W., Kalmbacher, R.S., Overman, A.J., Ruelke, O.C., Sonoda, R.M., Sotomayor-Rios, A., Stanley, Jr., R.L. & Williams, M.J., 1989. Florico stargrass. University of Florida Institute of Food and Agricultural Science Circular S-361. 15 pp.
• Skerman, P.J. & Riveros, F., 1990. Tropical grasses. FAO, Rome. pp. 316-318.

Authors

W.W. Hanna