Paspalum scrobiculatum (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Paspalum scrobiculatum L.

Protologue: Mant. Pl. 1: 29 (1767).

Family: Gramineae

Chromosome number: 2n= 20, 40, 60

Synonyms

* var. auriculatum : P. auriculatum Presl (1830), P. zollingeri Steudel (1853);

• var. bispicatum : P. commersonii Lamk (1791), P. cartilagineum Presl (1830);

• var. horneri : P. horneri Henrard (1935);

• var. lanceolatum : P. lamprocaryon K. Schum. (1895).

Vernacular names

• var. scrobiculatum : kodo or kodra millet (En)
• Indonesia: rebu bawang, rumput kinangan (Java), suket krisik (Madura).

• var. bispicatum : koda grass, scrobic (En)
• Indonesia: jaringan, rumput ketih belalang (Indonesian), kumpai batu (Kalimantan)
• Malaysia: pala belang, rumput tulo santadok
• Philippines: sabung-sabungan (Tagalog), bias-biasin (Visaya), tat-awwa (Bontok)
• Cambodia: smau 'ânnchien
• Thailand: ya-sakhorbik (central)
• Vietnam: co' san tru'_g, co' tru'_g.

Origin and geographic distribution

P. scrobiculatum occurs throughout the Old World tropics and is occasionally cultivated elsewhere. In India it is often also cultivated. In South-East Asia it is a common grass.

Uses

P. scrobiculatum provides useful forage but is also regarded as a weed of annual and plantation crops. Occasionally it is used as compost or mulch. In India it is cultivated for the grain.

Properties

Nitrogen concentrations of 1-5% during the growing season and below 0.5% in standover seed have been measured. It is a very palatable grass except when it is frosted. The cultivars grown for grain in India are said to contain compounds in the grain which are toxic to man and to animals. The fungi Sorosporium paspali and Uredo paspali-scrobiculari are almost invariably present in the outer husks of the grain and are thought to be responsible for its toxicity. In Australia it has not been toxic to grazing animals. There are 300-600 seeds/g.

Botany

A tufted perennial, not stoloniferous, with ascending to erect, sometimes branching culms up to 135 cm tall. Leaf-sheath glabrous or hairy at the margins; ligule collar-shaped, up to 1.8 mm long; leaf-blade linear, up to 53 cm × 2.5 cm, flat or folded length-wise, narrowed towards the base, hirsute at base, along the margins and above the ligule. Inflorescence composed of 1-14 alternate or subopposite racemes each up to 15 cm long; peduncle 0.5-2 mm in diameter; rachis flat, straight to slightly zigzag, winged,; spikelets solitary, imbricate or not, usually suborbicular, 2-3 mm long; lower glume usually absent; upper glume 5-13-nerved, sterile lemma 5-9-nerved. Caryopsis obovoid to ovoid, ca. 2 mm long.

P. scrobiculatum is a polymorphic species, possibly an aggregate swarm of apomicts. Although the variability is quite continuous, at present 5 varieties are distinguished with the following characteristics:

• var. scrobiculatum : culms 8-20(-55) cm long; cauline leaf-sheaths hairy at margins, rarely glabrous; leaf-blades (4-)7-20(-30) cm × (3-)5-7(-9) mm; peduncle 0.5-1 mm in diameter; racemes 1-2, alternate or subopposite, 1.5-7 cm long; spikelet 2.5-3.3 mm × 2.1-2.6 mm; upper glume with 7, 9 11 or 13 nearves; sterile lemma with 7 or 9 nerves. Distributed from India throughout Malesia to the Pacific. Its occurrence in Africa and elsewhere is uncertain.

• var. auriculatum (Presl) Merrill: culms up to 135 cm long; cauline leaf-sheaths glabrous; leaf-blades 20-40(-53) cm <> 10-16(-19) mm; peduncle 1-1.9 mm in diameter; racemes 3-8, alternate, 8-15.5 cm long; upper glume 7-nerved; sterile lemma with 7 or 9 nerves. Distributed from India throughout Malesia. Its occurrance in the rest of the world is uncertain.

• var. bispicatum Hackel: culms 8-70(-130) cm long; cauline leaf-sheaths glabrous or hirsute; leaf-blades 10-25(-42) cm × 4-9(-15) cm; peduncle 0.5-1.4 mm in diameter; racemes (1-)(2-6(-14), alternate, 1.5-9(-11) cm long; spikelet 1.8-2.6 mm × 1.5-2.2 mm; upper glume and sterile lemma 5 or 7 nerved. Distributed in tropical Africa, Asia (including Malesia), the Pacific and Australia.

• var. horneri (Henrard) Koning & Sosef: culms 15-80 cm long; cauline leaf-sheaths hirsute; leaf-blades 3-6 mm wide; racemes 1-4, alternate or subopposite; spikelets 1.7-2.5 mm × 1.2-1.9 mm; upper glume 5-nerved; sterile lemma 5 or 7-nerved. Distribution is disjunct: in Assam and in Malesia only.

• var. lanceolatum Koning & Sosef: cauline leaf-sheaths enveloping the nodes; leaf-blades 7-21 cm × 12-27 mm; racemes 2-4; spikelets 2-2.7 mm long. Distributed only in tropical Africa.

P. scrobiculatum flowers freely, and in Malaysia it produces seed during 3-4 months per year. The seeds fall as they mature.

P. orbiculare Forster f. much resembles P. scrobiculatum , especially var. bispicatum . Its spikelets are usually broadly obovate with 3 or 5 discolorous nerves in the upper glumes and sterile lemmas. In var. bispicatum the spikelets are usually suborbicular and the nerves are 5 or 7, concolorous. In Australia cultivar "Paltridge" of P. scrobiculatum was released in 1966, but it is now rarely cultivated.

Ecology

In Indonesia and Malaysia, P. scrobiculatum is found mostly in open, wet cultivated areas, up to 1200 m altitude, and in upland and tidal rice fields. It is commonly found on disturbed sites and is a weed in cropping land. It is well adapted to waterlogged soils and can tolerate flooding, but has only limited drought tolerance. The optimum temperature for growth is 25-27 °C. It is a sun-loving plant although it can tolerate and flourish with only 30-50% sunlight, as found in young rubber and oil palm plantations or black pepper farms. It is not as salt tolerant as the closely related P. vaginatum Swartz. It can tolerate poor soil fertility if there is little competition, but prefers very fertile soils and responds well to fertilizer application.

Agronomy

P. scrobiculatum can be propagated by seed or by rooted tillers. Newly ripened seeds are dormant and mechanical or acid scarification is desirable to reduce dormancy. It needs a very fine seed-bed which is usually prepared by ploughing, disking and harrowing. It is usually sown through a cereal drill in rows 1.3 m apart on a well-prepared seed-bed.

P. scrobiculatum is susceptible to a root-knot nematode ( Meloidogyne incognita ) and can be attacked by the Paspalum ergot ( Claviceps paspali ).

It is a very palatable and highly digestible grass during the wet season and retains these characteristics later into maturity than most other grasses. Consequently it could be used intensively during the dry season when the nutritive value of other species is generally lower. Strategic intermittent or rotational grazing helps to allow sufficient seeding for regeneration. Experience in Australia suggests that it will not persist in permanent pastures, where it is replaced by other perennial grasses.

It is usually harvested by grazing animals but is occasionally cut and fed as green fodder. Although usually not as persistent as other perennial tropical grasses, results from experiments with both sheep and cattle suggest that it can result in good animal production.

Genetic resources and breeding

There is considerable variation within P. scrobiculatum and closely related Paspalum species which might even belong to the same species complex. It is unlikely that any of the existing germplasm collections adequately document this variability. There are no breeding programmes on P. scrobiculatum .

Prospects

The present opportunistic use of P. scrobiculatum will continue. Studies on the variability within this species and on its agronomic requirements are necessary to determine its potential as a forage species. Australian experience suggests it may be more suited for use as a short-term forage rather than as a long-lived grass in permanent pastures.

Literature

• de Koning, R. & Sosef, M.S.M., 1985. The Malesian species of Paspalum (Gramineae). Blumea 30: 279-318.
• Devendra, C., 1979. Malaysian feedingstuffs. Malaysian Agricultural Research and Development Institute (MARDI), Selangor, Malaysia. 145 pp.
• Kitamura, M. & Nada, Y., 1986. Preliminary evaluation of 24 grasses introduced into sub-tropical Japan. Journal of Japanese Society of Grassland Science 32: 278-80.
• Oram, R.N., 1990. Register of Australian herbage plant cultivars. CSIRO, Australia. p. 44.
• Paltridge, T.B., 1955. Studies on sown pastures for southeastern Queensland. Bulletin No 274. CSIRO, Australia. pp. 15-51.
• Skerman, P.J. & Riveros, F., 1990. Tropical grasses. FAO, Rome. pp. 585-589.
• 't Mannetje, L., 1961. Key on vegetative characters of Paspalum species. CSIRO, Australia, Division of Tropical Crops and Pastures, Technical Paper No 1. pp. 6-7.

Authors

B.B. Baki & I.B. Ipor