Panicum repens (PROSEA)
- Protologue: Sp. Pl. ed. 2: 87 (1762).
- Family: Gramineae
- Chromosome number: 2n= 40
Panicum convolutum P. Beauv. ex Sprengel (1825).
- Torpedo grass (Am). Panic rampant (Fr)
- Indonesia: benda laut (North Sumatra), suket balungen (Javanese), ramput kumaranting (Minang)
- Malaysia: kerunong padi, metubong, telur ikan
- Philippines: luya-luyahan (Tagalog), luy-a-luy-a (Visaya), maralaya (Ilokano)
- Burma: myet-kha
- Cambodia: smau phluk, chhlong
- Thailand: ya-chanakat (central), ya-khaemman (northeast), ya-onoi (northern)
- Vietnam: co' cu'a gà, co' ô_g.
Origin and geographic distribution
Torpedo grass is widespread in Indonesia, Malaysia, Thailand and other South-East Asian countries and it also occurs in wetter areas throughout the tropical and subtropical regions of the world.
Torpedo grass is used as a forage for grazing or cutting. It is regarded as an excellent native forage in South-East Asia, being both nutritious and palatable. It is also used to control erosion on sandy soils, but it can be a serious weed in crops. Rhizomes from sandy soils are sometimes dug up and fed to cattle as they are very palatable.
Nitrogen concentrations in torpedo grass range from 0.7% to 3.8%.
A perennial grass with long, sharp pointed rhizomes and often also surface stolons; culms erect or decumbent, up to 120 cm tall, often from a knotty base. Leaf-sheath 4-7 cm long, hairy at the margins near the throat; leaf-blade linear-acuminate, 7-25 cm × 2-8 mm, flat or rolled when dry, often stiff and pungent, ascending close to the stem; ligule a shallow membrane, 0.5 mm high, fringed with whitish hairs. Inflorescence a narrowly oblong panicle, 5-20 cm long, sparsely to moderately branched, branches usually ascending; spikelets narrowly elliptical, ca. 3 mm long, acute, often tinged with purple; lower glume clasping the base of the spikelet, _ the length of the spikelet; upper glume as long as the spikelet; lower floret male, upper floret bisexual. Caryopsis glossy white.
Flowering starts 3-4 weeks after seedling emergence and continues throughout the year, but seed production is poor. Rhizomes develop so fast that they give a dense sward within 5-6 months.
Torpedo grass can grow up to 2000 m altitude in the tropics on humid or marshy places, on moist open or partially shaded meadows, in paddy fields, along lagoons, canals and roadsides, and on sandy soils on the coast. It is extrememly tolerant of acid soils. It cannot stand permanently flooded conditions.
Torpedo grass is established by seed or rhizomes. A seeding rate of about 10 kg/ha is used in some regions, sowing seed on the soil surface with only a light covering. Ploughing enhances subsequent spread. It is very palatable and extremely tolerant of heavy grazing. Frequent and close cutting or grazing is recommended to maintain plants in a leafy condition. It shows little response to liming in acid peat soils. Irrigated pastures, fertilized with 100 kg/ha of N at each of 5 cuts, have yielded 100 t/ha per year of green matter. On abandoned rice fields it has yielded 60 t/ha per year of green matter. On peat soils, it can yield up to 11 t/ha of DM per year.
As a weed it is difficult to control because of the long-living and deep penetrating rhizomes; it may spread into improved pastures competing with and choking out desirable species.
Genetic resources and breeding
Observations suggest that torpedo grass is a variable species, but it is unlikely that any substantial germplasm collections are being maintained.
Torpedo grass is a useful local forage grass. Selection should aim at obtaining accessions with more leaf, less stem, and less agressive rhizomes.
- Bor, N.L., 1960. The grasses of Burma, Ceylon, India and Pakistan. Pergamon Press, London. p. 330.
- Manidool, C., 1989. Natural grassland and native grasses of Thailand [in Thai]. Technical Bulletin No 1301-26-32. Division of Animal Nutrition, Department of Livestock Development, Bangkok. p. 22.
- Manidool, C., Vagama, V. & Poositikul, A., 1985. Digestibility of Panicum repens from organic soils area in Pikulthong village [in Thai]. Annual Report on Animal Production Research. Department of Livestock Development, Bangkok.
- Mehra, K.L. & Fachrurozi, Z., 1985. Indonesian economic plant resources: forage crops. Lembaga Biologi Nasional - LIPI, Bogor, No 31. p. 31.
- Skerman, P.J. & Riveros, F., 1990. Tropical grasses. FAO, Rome. pp. 543-545.