Centrosema acutifolium Benth.

 

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Leguminoseae

Common names

Acutifolium

Author: L.’t Mannetje
Origin and geographic distribution


The origin of Centrosema acutifolium is between 4°-6° N in Colombia and Venezuela (var. orinocense) and in central-west and south-east Brazil (var. matogrossense). It has been introduced for testing in several tropical countries, including South-East Asia, Australia and several countries in Latin America.

Description

Perennial, trailing-twining herb; slender stems, pubescent, with tendency to root at nodes. Leaves trifoliolate, young leaflets distinctly purplish; stipules deltoid-acuminate,
pubescent; petioles and petiolules pubescent, reddish at their base; leaflets ovate to ovate-lanceolate, apically acuminate, membranaceous, puberulous to subglabrous on both surfaces; central leaflet symmetrical, 5-8.5 cm x 3-3.5 cm; lateral leaflets asymmetrical, 4-7.5 cm x 2.5-4 cm. Inflorescence an axillary raceme with up to 24 flowers inserted by pairs along the rachis; peduncle conspicuously long, up to 24 cm, pubescent; flower
subtended by a pair of short, ovate-acuminate bracteoles; calyx campanulate, 5-toothed, pilose, carinal and lateral teeth short; petals light violet; standard orbicular emarginate, 28-35 mm x 32-40 mm, pubescent outside. Pod linear, straight to slightly bent, up to 20 cm long, beaked, scabrid, containing 10-15 seeds, dehiscent. Seed cylindrical, 5-7 mm x ca. 3 mm, greenish-yellow with dark, fine mottles (Schultze-Kraft, 1992).

There are two morphologically and physiologically distinct forms of C. acutifolium related to their geographical origin: (1) var. orinocense nom. nud. from a small distribution niche in Colombia and Venezuela, and (2) var. matogrossense nom.
nud. from central-west Brazil. The species description refers to var. orinocense.

C. acutifolium is closely related to C. pubescens Benth. and the species are morphologically very similar. The main characteristics that distinguish C. acutifolium are: (1) the purplish colour of young leaflets, (2) the short bracteoles and calyx teeth, (3) the scabrid pod indumentum, and (4) the cylindrical seeds (Schultze-Kraft, 1992).

Use

C. acutifolium is used as forage in grazed pastures or in cut-and-carry systems. Optimal cutting intervals depend on soil moisture and fertility; a 10-14 week cutting interval and a 10-15 cm cutting height are suggested. It is an effective understorey for timber trees and in coconut plantations with about 60 % light transmission. A cultivar 'Vichada' has been released in Colombia (Ramírez, 1987).

Properties

Depending on plant age, N concentrations in leaves range from 3.5-5.0%,
and in vitro DM digestibility from 45-75%. Phosphorus concentrations in leaves range from 0.14-0.27%, and Ca from 0.38-1.13%. There are 15-20 seeds/g.

Toxicity

None reported.

Ecology

C. acutifolium is best adapted to sub-humid, tropical environments with 1000-2500 mm rainfall per year and a distinct dry season of up to 5 dry months. Var. orinocense requires well-drained, light-textured soils, whereas var. matogrossense grows particularly well on heavier soils, including those with seasonal drainage problems. Its shade tolerance is moderate (Schultze-Kraft & Clements,1990).

Soil requirements

C. acutifolium tolerates soils of low pH and toxic levels of Al and Mn very well; its nutrient requirements are low.

Propagation and planting

C. acutifolium seed is drilled in rows or broadcast, simultaneously with a grass, or strip-sown into existing grass-swards at 3-4 kg/ha. Mechanical or acid-scarification of seed is recommended to overcome hard-seededness. C. acutifolium can be grown in association with bunch grasses such as guinea grass (Panicum maximum Jacq.) on fertile soils, or gamba grass (Andropogon gayanus Kunth) on infertile soils. Successful associations have also been obtained with the stoloniferous Brachiaria dictyoneura (Fig. & De Not.) Stapf. (Schultze-Kraft, 1992).

Rhizobial requirements

Although it can nodulate effectively from native cowpea rhizobia (Tang et al., 1994) inoculation with a rhizobial strain of known effectiveness is recommended.

Growth and development

C. acutifolium flowers late in the season, and this can reduce seed production in years with an early onset of the dry season. As a result, seed yields are often low, but under
adequate soil moisture conditions, seed production potential is high (Diulgheroff et al., 1990).

Diseases and pests

C. acutifolium shows good tolerance to the major centrosema diseases in sub-humid environments. It is, however, more susceptible to Pseudomonas bacterial blight
than other Centrosema spp. Leaf-eating insects can be a problem during dry periods.

Performance

Wet-season DM yields on acid soils of low fertility can be as high as 3 t/ha per 12 weeks; on soils of somewhat better fertility they can reach 5 t/ha. Dry-season DM yields seldom exceed 1 t/ha per 12 weeks. C. acutifolium was more productive and persistent than the other Centrosema spp., regardless of companion grass, and this was associated with higher liveweight gains, particularly during the dry season (Lascano et al. 1989). In association with gamba grass, 180 kg liveweight gain per steer per year has been measured as compared with 110 kg/steer per year from gamba grass alone. Milk yield in association with gamba grass was increased 15% (1.2 kg) compared to grass alone (Lascano and Avila, 1991). For cut-and-carry systems, however, it is inferior to C. macrocarpum because of lower DM production. The seed production potential is high; yields up to 700 kg/ha can be obtained.

Links

References

Diulgheroff S. et al. (1990); Lascano C. E. and Avila P. (1991); Lascano C. et al. (1989); Ramirez P. A. (1987); Schultze-Kraft R. (1992); Schultze-Kraft R. and Clements R.J. (Eds) (1990); Tang M. et al, (1994)

[Comments from Prof. Dr Rainer Schultze-Kraft are acknowledged]