Paspalum plicatulum (PROSEA)
Paspalum plicatulum Michaux
- Protologue: Fl. Bor. Amer. 1: 45 (1803).
- Family: Gramineae
- Chromosome number: 2n= 20 (diploid), 30, 40, 60
Paspalum undulatum Poiret (1804), Panicum plicatulum (Michaux) Kuntze (1898).
- Plicatulum, brown seed paspalum, brown top paspalum (En, Am). Herbe à cheval (Fr)
- Thailand: ya-phlikhathiulum.
Origin and geographic distribution
Plicatulum occurs naturally in South and Central America. It is distributed throughout the world from Africa (Kenya, Ivory Coast) to Australia, the United States, Oceania (Fiji) and South-East Asia (including the Philippines, Thailand, Indonesia, Malaysia and China).
Plicatulum is used as a pasture grass for grazing and silage or hay making, as an understorey in coconut plantations and in ley pastures after harvesting a paddy rice crop.
Nitrogen concentration ranges from 0.8-2.0% of the DM and DM digestibility from 39-50% of whole plant material and 50-70% of green leaves. Plicatulum is a palatable grass with a high nutritive value at the young leafy stage of growth. "Hartley" maintains a high nutritive value after frosting, in contrast to "Rodds Bay". There are 750-1200 seeds/g.
A tufted, decumbent perennial, growing to a height of 1.2 m, sometimes with a short rhizome. Leaf-sheath keeled, usually glabrous; ligule membranous, 1-3 mm tall; leaf-blade folded at the base, linear 10-50(-85) cm × 3-7(-10) mm, often slightly hairy on the upper surface towards the base, in the tropics often hairy on both surfaces. Inflorescence a panicle composed of (5-)10-13(-19) racemes 2-10 cm long; spikelets in pairs (one of the pair sometimes undeveloped), obovoid-ellipsoidal, 2-3 mm × 1.5-2 mm; lower glumes absent; lower lemma with short transverse wrinkles just inside the slightly raised margin. Caryopsis as large as the spikelet, dark-brown, shiny.
Growth and development Plicatulum has a slow seedling growth, but rapid growth rate once established. It is a short-day plant, with a critical photoperiod of 13 hours and a short flowering period at the end of the wet season. Seed is ready for harvesting 21 days after panicle emergence. Seedlings have a juvenile period of 50-60 days in which they will not flower.
Other botanical information Three cultivars have been released in Queensland, Australia, viz. "Rodds Bay", with narrower leaves than the other two cultivars; "Hartley", more prostrate growing and leaves with wavy margins towards the base; "Bryan" is intermediate to these two cultivars and is the hairiest one.
Plicatulum is adapted to tropical and subtropical climates with over 750 mm of annual rainfall. Plicatulum survives dry seasons of 5-6 months. "Rodd's Bay" has the best drought tolerance. Temporary waterlogging is also tolerated. Plicatulum does not grow at temperatures below 10 °C and top growth is killed by frost, although regrowth occurs in spring. Optimal temperature for germination and growth is between 20-35 °C. The grass can grow on a wide range of soils; it is very tolerant of low pH and of high Al concentrations. Plicatulum is tolerant of fire, but it is not adapted to shade.
and planting Plicatulum is propagated normally by seed, but can also be planted vegetatively. The seed can remain dormant for several months after maturity. This is caused by permeability restrictions imposed by the lemma and the palea. Dormancy can be broken by chilling at 7 °C for 30 days. Full land preparation to a fine seed-bed is necessary and the recommended seeding rate is 2-3 kg/ha. The seed can be broadcast on the surface and covered by rolling, or drilled to a depth of 1-1.5 cm. Plicatulum can be grown in association with Macroptilium atropurpureum (DC.) Urban, Stylosanthes spp., Desmodium intortum (Miller) Urban and Trifolium repens L.
Plicatulum responds well to N fertilizer, but it can also grow and persist on poor soils. Plicatulum can be grazed continuously or rotationally.
Diseases and pests Plicatulum is very resistant to ergot and no other diseases or pests are known to affect it.
Dry matter yield varies from 8.5-24 t/ha per year. With irrigation and complete fertilizer (NPK) and cutting intervals of five weeks, DM yield per cut of 2.5 t/ha can be obtained.
In Fiji DM yield under coconut was 9.5 t/ha per year, while in Malaysia the yield under oil palm was negligible. Seed harvest yields 200-300 kg/ha.
Annual liveweight gains of beef cattle of up to 250-300 kg/ha have been measured in the sub-humid subtropics in Queensland.
Genetic resources and breeding
Plicatulum is an aposporous apomict (2 n = 40), or sexual (2 n = 20). A germplasm collection of plicatulum is maintained at ATFGRC (CSIRO, Australia). Seed is also produced in Queensland. There are no known breeding programmes with plicatulum.
Plicatulum has good prospects for use in open pastures in subtropical and tropical regions of South-East Asia because of its persistence even on infertile soils and its ability to combine with legumes.
- Bisset, W.J., 1975. Plicatulum finds a place in coastal pastures. Queensland Agricultural Journal 101: 603-608.
- Bogdan, A.V., 1977. Tropical pasture and fodder plants. Longman, London and New York. pp. 213-214.
- Bryan, W.W. & Shaw, N.H., 1964. Paspalum plicatulum Michx. Two useful varieties for pastures in regions of summer rainfall. Australian Journal of Experimental Agriculture and Animal Husbandry 4: 17-21.
- Skerman, P.J. & Riveros, F., 1990. Tropical grasses. FAO, Rome. pp. 579-584.
- 't Mannetje, L., 1961. Key on vegetative characters of Paspalum species. CSIRO, Australia, Division of Tropical Pastures, Technical Paper No 1. pp. 7-8.
L. 't Mannetje & S.M.M. Kersten