Digitaria ciliaris (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Digitaria ciliaris (Retzius) Koeler

Protologue: Descr. Gram.: 27 (1802).

Family: Gramineae

Chromosome number: 2n= 54

Synomyms Digitaria marginata Link (1821), D. sanguinalis auct., non Scop. (e.g. in Heyne, 1927), D. adscendens Henrard (1934).

Vernacular names

• Tropical finger grass, summer grass (Australia) (En). Crab grass (Am)
• Indonesia: jelamparam, suket ceker ayam (Javanese), jampang jemprak (Sundanese)
• Malaysia: caker ayam, bamboo grass
• Philippines: baludyangan (Tagalog), saka-saka (Ilokano)
• Thailand: yah-tin-nok, ya-plongkhaonok (central)
• Vietnam: túc hi[n]h leo.

Origin and geographic distribution

D. ciliaris is widely distributed throughout the tropics and subtropics, especially in Asia. It is much less common in Africa.

Uses

Although a bad weed in cropping areas, D. ciliaris provides good forage, assists in protecting soil against erosion and provides material for mulch or compost.

Properties

D. ciliaris is a palatable grass, especially when young. Pen feeding trials in the United States showed that it had a similar digestibility and higher N concentration than sudan grass ( Sorghum ×drummondii (Steud.) Millsp. & Chase or pearl millet ( Pennisetum americanum (L.) K. Schum. ex Leeke).

Botany

Tufted annual, rarely short-lived perennial; culms erect, ascendent or prostrate, 50-100 cm long, often rooting at the lower nodes and forming loose mats. Leaf-sheath loose, variously pilose; ligule membranous, truncate, up to 3 mm long; leaf-blade lanceolate to linear, 2-25 cm × 3-13 mm, short bristly on both sides or glabrous. Inflorescence consisting of 2-10 racemes, each up to 15(-22) cm long, digitately arranged or in 2-3 whorls; peduncle up to 40 cm long; rachis characteristically winged, serrate, spicules at least 0.05 mm long; spikelets binate, homomorphous, lanceolate, 2.5-3.5 mm long, smoothly hairy; two florets per spikelet, the upper bisexual, the lower neutral. Caryopsis oblongoid, about 2 mm long, golden brown to grey.

A very variable species, about which much confusion exists in the taxonomic literature where it has been given more than 50 different names. Four variable characters are responsible: the hairs on the rachis, the ciliate frill around the spikelets, the occurrence of glassy bristles, and the spacing of the nerves in the lower lemma.

D. ciliaris is an agressive and opportunistic colonizer of bare, disturbed or newly cleared habitats due to its prolific seed production, vigorous growth and rapid development of rooted stolons. Seeds germinate in spring or summer in temperate or subtropical areas or with the onset of rains in the tropics.

Ecology

In the tropics, D. ciliaris grows at altitudes from sea-level up to 1600 m (Indonesia) or 2000 m (Papua New Guinea). It grows best in moist, sandy or loamy soils and is very responsive to high soil fertility.

Agronomy

D. ciliaris is propagated vegetatively or by seed. If newly ripened seed is being used for sowing, treatment with alternating temperatures and scarification helps to reduce dormancy. Germination is also stimulated by exposure to light. The spikelet scales act as a barrier to oxygen entry for up to 4 months storage time. A relatively high N level in the substrate seems to be needed for optimal germination. Seed dormancy can last up to 7 months. Good seed-bed preparation and sowing rates of 2-3 kg/ha of seed help to ensure good establishment. Planting with rooted cuttings, at spacings of about 10 cm × 10 cm, gives more rapid establishment than sowing seed.

D. ciliaris is usually eaten by grazing animals, but it can be cut for stall feeding or for silage. It is tolerant of close cutting or grazing. It may produce several seed crops per year if periodically grazed or mown. Its presence in pastures is usually a sign of newly established pastures, recent cultivation or disturbance, or deterioration of perennial grasses. It is usually a minor component or is not found in vigorous stands of perennial grasses. Pure stands have produced DM yields of 10-12 t/ha per year. One disadvantage of D. ciliaris is that it is an alternative host of the viruses that produce stripe disease and black-streak dwarf disease in rice.

Genetic resources and breeding

D. ciliaris is a very variable species, but it is unlikely that substantial germplasm collections are being maintained. There are no known breeding programmes.

Prospects

D. ciliaris will continue to be a useful natural forage in specific situations, usually associated with disturbance or cropping. It is unlikely that it will be deliberately propagated more widely than at present. In Malaysia, where D. ciliaris prevails as a weed under rubber and oil palm, sheep grazing will reduce its weed impact.

Literature

• Holm, L.G., Plucknett, D.L., Pancho, J.V. & Herberger, J.P., 1977. The world's worst weeds: distribution and biology. The East-West Center, University of Hawaii Press, Honolulu, Hawaii, United States. pp. 249-253.
• Skerman, P.J. & Riveros, F., 1990. Tropical grasses. FAO, Rome. pp. 348-350.
• Soerjani, M., Kostermans, A.J.G.H. & Tjitrosoepomo, G., 1987. Weeds of rice in Indonesia. Balai Pustaka, Jakarta. pp. 402-404.
• Veldkamp, J.F., 1973. A revision of Digitaria Haller (Gramineae) in Malesia. Blumea 21: 32-35.

Authors

B.B. Baki, C.P. Chen & I.B. Ipor