Paspalum conjugatum (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Paspalum conjugatum Bergius

Protologue: Act. Helv. Phys. Math. 7: 129, t.8 (1762).

Family: Gramineae

Chromosome number: 2n= 20, 40, 80

Vernacular names

• Buffalo grass, carabao grass, sour paspalum (En)
• Indonesia: jampang pahit (Sundanese), paitan (Javanese), klamaran (Madura)
• Malaysia: rumput kerbau, rumput ala negri
• Philippines: kulape (Tagalog), kauat-kauat (Visaya), kalo-kawayan (Ilokano)
• Thailand: ya-nomnon, ya-hep (southern)
• Vietnam: cò san c_p.

Origin and geographic distribution

Originally from the American tropics, P. conjugatum is naturalized throughout South-East Asia and in many tropical countries of the world. It is abundant in Indonesia, the Philippines and the Pacific Islands.

Uses

P. conjugatum is used as a forage for grazing or in cut-and-carry systems, and is rated as very important as a natural pasture grass in coconut plantations. It is occasionally used as a lawn grass and is also regarded as an important weed in rice and plantation crops.

The Iban of Borneo use leaf decoctions in the treatment of wounds and sores, and in the Sepik area of Papua New Guinea crushed spikelets are used for the same purpose.

Properties

At the pre-flowering stage, the N concentration in P. conjugatum ranges from 1-2.2%. It is stated that only the young stage of the grass is suitable for grazing since the fruits tend to stick in the throats of livestock and choke them. The presence of a haemostatic glucoside, which reduced the time for blood clotting by 50%, has been reported for this species. Wet fruits may become very irritating as they easily stick to one's legs and clothing.

Botany

A vigorous, creeping perennial with long stolons, rooting at nodes, with culms ascending to erect, 40-80(-100) cm tall, branching, solid, slightly compressed. Leaf-sheath strongly compressed, usually 30-50 mm long, ciliate on the margins; ligule collar-shaped, about 1 mm long; leaf-blade linear or lanceolate-acuminate, 8-20 cm × 5-12 mm, glabrous to sparsely pubescent. Inflorescence well exserted with two or occasionally three diverging racemes, 7-16 cm long; spikelets solitary, imbricate, flattened ovate, up to 2 mm long, with long hairs on the margins; lower glume absent, upper glume with a fringe of long hairs (1 mm) along its margin. Caryopsis broadly ovoid, plano-convex, about 1 mm long, dark brown.

The germination percentage of P. conjugatum seed is usually low. Flowering commences 4-5 weeks after seedling emergence and it continues to flower year round. New shoots develop at every rooted node.

Ecology

P. conjugatum grows from near sea-level up to 1700 m altitude in open to moderately shaded places. It is adapted to humid climates. It is found under plantation crops and also along stream banks, roadsides and in disturbed areas on a variety of soils, often growing gregariously.

Agronomy

P. conjugatum is propagated from prostate culms, using 2-3 nodes per cutting. Close grazing is required to keep it in palatable stage as palatability declines rapidly after flowering. It is eaten more readily by water buffaloes than by cattle. In a mixture with Imperata cylindrica (L.) Raeuschel, it will dominate the latter if the pasture is grazed heavily. Close cutting and heavy grazing are recommended since it is tolerant of defoliation, and because this prevents seed head maturity, resulting in higher quality regrowth. Cut feed can be conserved as hay. Under a coconut plantation without any fertilizer a yield of 19 t/ha of green material has been obtained. Yield increased to 30 t/ha of green material following application of 15-15-15 N:P:K fertilizer at 310 kg/ha.

Genetic resources and breeding

It is unlikely that substantial germplasm collections are being maintained.

Prospects

Because of the wide distribution of P. conjugatum , research on agronomic aspects, such as improving DM yield and seed production, is desirable.

Literature

• de Koning, R. & Sosef, M.S.M., 1985. The Malesian species of Paspalum (Gramineae). Blumea 30: 279-318.
• Gilliland, H.B., Holttum, R.E. & Bor, N.L., 1971. Grasses of Malaya. In: Burkill, H.M. (Editor): Flora of Malaya. Vol. 3. Government Printing Office, Singapore. pp. 180-182.
• Holm, J., 1971. Feeding tables. Nutrition Laboratory of Thai-German Dairy Project, Livestock Breeding Station, Chiangmai, Thailand.
• 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. 45 pp.
• Mehra, K.L. & Fachrurozi, Z., 1985. Indonesian economic plant resources: forage crops. Lembaga Biologi Nasional - LIPI, Bogor, No 31. p. 32.
• Plucknett, D.L., 1979. Managing pastures and cattle under coconuts. Westview Tropical Agriculture Series, No 2. Westview Press, Boulder, Colorado, United States. 364 pp.

Authors

C. Manidool