Tripsacum andersonii (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Tripsacum andersonii J.R. Gray

Protologue: Phytologia 33: 204 (1976).

Family: Gramineae

Chromosome number: 2n= 64

Vernacular names

• Guatemala grass (En)
• Malaysia: rumput jelai, rumput jagung
• Thailand: ya-kuatemala.

Origin and geographic distribution

Guatemala grass is native to Central America and northern South America (from Mexico to Peru). It is now widely cultivated throughout the tropics including South-East Asia.

Uses

Green foliage of Guatemala grass is widely used as cut fodder. In Sri Lanka, it has been used as a soil cover in tea plantations. In Malaysia, it has been planted extensively in rubber and oil palm estates for control of erosion, for mulching and as a soil conditioner in drained swamps. It can be a weed in cultivated areas.

Properties

Regrowth harvested at 4, 6, 10 and 12 weeks had N concentrations of 2.2, 2.1, 1.3 and 0.8%. Digestible crude protein percentages at the same growth stages were 9.8%, 9.1%, 5.0% and 2.2% as assessed by using cattle. Six-week-old regrowth from plants grown on "acid sulphate" soil contained 1.5% N, 0.14% P, 2.6% K, 0.13% Ca and 0.11% Mg.

Botany

Robust perennial grass, forming large mats up to 5 m across of tangled stolons and rhizomes, from which erect to decumbent flowering culms are produced; stolons and culms up to 5 cm in diameter, flowering culms 2-3 m tall. Lower leaf-sheaths shortly pubescent near the base, upper ones glabrous; ligule a membraneous ridge, slightly hairy behind; leaf-blade sessile, linear-lanceolate, up to 120 cm × 5-10 cm, shortly tomentose above, glabrous below. Inflorescences terminal and axillary, composed of 3-7 branches (terminal) and 1-4 branches (axillary); branches subdigitately arranged on a short primary axis and each raceme consists of several basal fruitcases (pistillate spikelets) with numerous staminate spikelets on a continuous rachis above them; pistillate spikelets 6-10 mm long, sunken in cavities of the indurated rachis and covered by the outer glume, disarticulating individually at maturity; staminate spikelets paired at each rachis node (one sessile, one shortly pedicelled), 6-10 mm long, with coriaceous 10-15-nerved glumes.

In Central America T. andersonii is often confused with T. latifolium Hitchcock (2 n = 36), T. laxum Nash (2 n = 36), and T. maizar Hernandez & Randolph (2 n = 36, 72). T. laxum and T. maizar bear 10-50 racemes per terminal inflorescence and the male section of each raceme is typically pendent. T. latifolium has sessile, 4-6 mm long, staminate spikelets. T. andersonii is very sterile.

Ecology

Although known for its excellent performance in lowland conditions, vigorous growth in suitable sites at higher altitudes (about 1800 m) has also been observed. Good growth can also be maintained when planted in plantations with about 50% shade. It is adapted to a wide range of soil types including ultisols, oxisols, peats, acid sulphate soils and Bris soils (coastal marine sands) with a pH(H₂O) range of 2.7-4.5. Guatemala grass is adapted to inundated and marshy conditions. It has remarkable tolerance to shallow water tables, but poor tolerance to soil moisture stress.

Agronomy

Guatemala grass is planted vegetatively, either through splitting the rooted tillers from clumps, by rhizomes or through stem cuttings containing 3 nodes. There are no known commercial suppliers of seed in South-East Asia.

Green foliage is cut by hand for pen feeding rather than being conserved for hay. The vigorous growth of Guatemala grass has been demonstrated in its annual DM yields, at a 6-week cutting interval with maintenance fertilization of 200 kg/ha of N, 40 kg/ha of P and 100 kg/ha of K per year, of 23 t/ha on a sedimentary soil, 21 t on a peat soil, 24 t on an acid sulphate soil and 2 t on a Bris soil. The low production on the Bris soil is attributed to water stress and high soil temperatures. It outyielded 20 other grass species on acid sulphate soil. While only 30% of plants died over a 3-year cutting experiment, mortality might have been higher if plants had been subjected to more frequent defoliation. Adequate soil moisture (either from rainfall or irrigation) and fertilizer are the two important factors involved in maintaining productive Guatemala grass. In view of its declining quality with increasing age of regrowth, supplementation with a leguminous shrub such as Leucaena leucocephala (Lamk) de Wit may best exploit its high yield potential to optimize animal production. No serious disease or pest problems have been noted so far.

Genetic resources and breeding

It is unlikely that any substantial germplasm collections are being maintained and there are no known breeding programmes. T. andersonii behaves cytologically as if its genome consists of a triploid Tripsacum L. genome (54 chromosomes) and a haploid Zea L. genome (10 chromosomes). Cytogenetic studies indicate that T. andersonii originated as a hybrid between a species of Tripsacum (2 n = 36) and a species of Zea (2 n = 20). The Tripsacum parent probably was T. latifolium of Central America and the Zea parent either Z. mays L. ssp. mays (domesticated maize) or Z. mays L. ssp. mexicana (Schrad.) Iltis (annual teosinte).

T. andersonii is remarkably uniform morphologically, indicating that the species had a single hybrid origin. Its wide distribution in Central and South America suggests a rather ancient origin.

Prospects

Under high rainfall tropical environments, Guatemala grass is a proven species for erosion control, soil conditioning and mulching, and it is also a high-yielding forage species. If combined with legumes in a feeding system, its utilization for animal production could be further improved.

Literature

• Aminah, A. & Wong, C. C., 1991. Dry matter productivity and chemical composition of some promising grasses grown on acid sulphate soil. In: Recent innovation in the animal and animal products industry. 14th Malaysian Society for Animal Production (MSAP) Conference, Genting Highlands, Malaysia, May 8-9, 1991. MSAP and The Federation of Livestock Farmers Association of Malaysia (FLFAM), Kuala Lumpur. pp. 92-96.
• Devendra, C., 1979. Malaysian feedingstuffs. MARDI, Kuala Lumpur, Malaysia. 145 pp.
• de Wet, J.M.J., Fletcher, G.B., Hilu, K.W. & Harlan, J.R., 1983. Origin of Tripsacum andersonii (Gramineae). American Journal of Botany 70: 706-711.
• de Wet, J.M.J., Gray, J.R. & Harlan, J.R., 1976. Systematics of Tripsacum (Gramineae). Phytologia 33: 203-227.
• Wong, C.C., Chen, C.P. & Ajit, S.S., 1982. A report on pasture and fodder introduction in MARDI. MARDI Report No 76. MARDI, Kuala Lumpur. 35 pp.
• Wycherley, P.R. & Ahmad Azli, M.Y., 1974. Grasses in Malaysian plantations. Rubber Research Institute of Malaysia. Rajiv Printers, Kuala Lumpur. pp. 58-59.

Authors

C.P. Chen