Ischaemum rugosum (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Ischaemum rugosum Salisb.

Protologue: Icon. Stirp. Rar.: 1, fig. 1 (1791).

Family: Gramineae

Chromosome number: 2n= 18, 20

Synonyms

Ischaemum colladoa Sprengel (1825), I. segetum Trinius (1832).

Vernacular names

• Wrinkle duck-beak, saramattagrass, wrinkled grass (En)
• Indonesia: suket blembem (Javanese), jukut randan (Sundanese)
• Malaysia: rumput mele (Sarawak), rumput ekor chawi, rumput colok cinia (Peninsular Malaysia)
• Philippines: tinitrigo (Tagalog), daua (Subanum), gulong lapas (Pangasinan)
• Burma: ka-gyi-the-myet
• Cambodia: smao srauv
• Thailand: ya daeng (central), ka-du-ai-nu, ya-noksichomphu
• Vietnam: mô[m] u.

Origin and geographic distribution

I. rugosum is indigenous to tropical Asia and is widely distributed throughout the tropics.

Uses

I. rugosum is used as forage. It is a serious weed in many crops, particularly in rice fields. It also provides suitable material for compost and mulch. In times of scarcity the grain is eaten by people.

Properties

The forage quality of I. rugosum declines quickly with age of the material. Nitrogen concentration ranges from 0.5-1.2%.

Botany

A vigourous perennial or annual (in strongly desiccating soil) tufted grass, sometimes with stilt roots, rooting at the nodes, with erect, slanting or ascending, often much branched culms, up to 1.5 m tall. Leaf-sheath long-auricled, ciliate along outer margin, densely soft hairy on node; ligule a brownish truncate membrane, 1-7 mm long; leaf-blade linear, 10-40 cm × 1-4 cm, apex acute, rarely hairy with long slender hairs. Inflorescence terminal, well exserted, composed of 2 racemes that are firmly appressed together and interlocked when young, separating when mature, each 3-12 cm long; spikelets binate, dissimilar, one sessile at the abaxial side of the rachis, one stalked at the adaxial side, provided with a short blunt hairy callus; sessile spikelet 5-6 mm long, 2-flowered, lower floret male or neuter, upper one bisexual; lower glume strongly transversely 5-7-ribbed, and winged above; upper lemma deeply 2-cleft and with 1-2 cm long awn which is twisted basally; pedicelled spikelet more or less reduced, pedicel up to 2 mm long, hairy, confluent with the callus. Caryopsis ovoid, 2 mm long, brown.

It is a very variable species. Two varieties have been distinguished: var. rugosum , with developed pedicelled spikelets, and var. segetum Hackel, with much reduced pedicelled spikelets; they are not separated geographically.

Seeds germinate early in the wet season and grow vigorously. Swards may form a dense mass of sturdy culms 25-30 weeks after germination.

Ecology

I. rugosum is an opportunistic and effective coloniser of open, disturbed or newly cleared areas. Although a sun-loving plant it can persist in sites receiving only 30-35% of full sunlight. It occurs at altitudes of up to 2400 m in the Philippines. I. rugosum is particularly well adapted to wet sites, and is often found in rice fields or low lying areas that are periodically flooded. It tolerates acid soils of pH(H₂O) 4.0.

Agronomy

I. rugosum can be established by seeds or rooted culms. Newly harvested seeds appear to have innate or induced dormancy, and scarification is desirable to reduce hard-seededness. When sowing seed, good seed-bed preparation assists in obtaining good establishment and seedling growth. Planting rooted culms at a 25 cm × 25 cm spacing will result in faster sward development than using seed. Although it will persist on soils of poor fertility, it will respond to fertilizer application.

I. rugosum has no major diseases or pests. Infestations by Puccinia spp. are commonly observed; they may reduce the quantity and quality of feed available, but control by chemicals is not warranted. It is an alternative host of the viruses causing rice and maize leaf blight galls and of Piricularia sp.

It can be grazed, but will not persist when continuously grazed by large ruminants at high stocking rates. When it is growing in water, the tops above water level can be cut and fed to animals. It is usually fed when fresh, but can be ensiled or dried and conserved for dry season feeding.

Genetic resources and breeding

It is a very variable species, but it is unlikely that substantial germplasm collections are being maintained.

Prospects

I. rugosum will continue to provide useful forage in existing feeding systems. As it is a very variable species, there is potential for selecting for better forage types and for studies on its agronomic requirements and grazing management.

Literature

• Bor, N.L., 1960. The grasses of Burma, Ceylon, India and Pakistan. Pergamon Press, London. pp. 184-185.
• 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. p. 259.
• 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. 295-298.
• 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. 19.
• Mehra, K.L. & Fachrurozi, Z., 1985. Indonesian economic plant resources: forage crops. Lembaga Biologi Nasional - LIPI, Bogor, No 31. p. 21.
• Soerjani, M., Kostermans, A.J.G.H. & Tjitrosoepomo, G., 1987. Weeds of rice in Indonesia. Balai Pustaka, Jakarta. No 3521. pp. 440-441.

Authors

B.B. Baki & C. Manidool