Aeschynomene histrix Poiret
Jointvetch, Porcupine Jointvetch
|Authors: Michael Peters
and Rainer Schultze-Kraft
Taxonomy and synonyms
The taxonomy of Aeschynomene histrix is complex (Rudd, 1955, 1959; W3Tropicos, 2001): six botanical varieties and one taxon at the forma level are recognized, and there are six species synonyms, but none of them are used in any earlier or current non-botanical, i.e. agriculture-related, literature.
The genus name Aeschynomene is derived from the Greek word meaning ashamed and refers to a certain degree of leaf sensitivity of some species to touch and temperature. A. histrix belongs to the series Viscidulae, section Ochopodium, subtribe Aeschynomeninae, tribe Hedysareae, subfamily Lotoideae in the family Fabaceae (or Papilionaceae) (Rudd, 1955).
Aeschynomene histrix has been described in the literature as having a prostrate to semi-erect growth habit (Rudd, 1955; Kretschmer & Bullock, 1980; Bishop et al., 1988). Merkel et al. (2000), in a field study of a 65-accession collection of A. histrix in Ibadan, Nigeria, identified five growth habit groups: (1) semi-erect, low plant height; (2) prostrate, low soil cover; (3) decumbent, good soil cover; (4) decumbent or semi-erect, few branches, thick stems, low soil cover; (5) (semi-) erect, many branches, good soil cover, shrubby. Plant height is reported to be < 25-80 cm, lateral spread of 75-160 cm (Kretschmer & Bullock, 1980; Bishop et al., 1988).
The following description is based on Rudd (1955): Perennial, tap-rooted herb or subshrub; stem moderately pubescent and hispid, with yellowish glandular hairs 2-4 mm long; stipules lanceolate, acuminate, 4-10 mm long, subglabrous to hispid; leaves 16-30 foliate, leaflets oblong-elliptic, rarely obovate, 4-12 mm long, 1.5-4 mm wide, obtuse to acute, upper surface pubescent to glabrous, lower surface pubescent; inflorescense axillary, 4-15 flowered, flower papilionaceous, 5-7 mm long , calyx 2-3 mm long; seeds 1.5-2 mm long, 1-1.5 mm wide, black. Merkel et al. (2000) report white, yellow and orange flowers. Thousand seed weight is 1-2.4 g (Bishop et al., 1988).
Aeschynomene species are reported to be mostly self-fertilising (Kalin Arroyo, 1978), but regarding A. histrix there is no concrete information. Time to flowering of A. histrix varies between 43 to 306 days after planting (Merkel, 1996; Kretschmer & Bullock, 1980).
Geographic distribution and adaptation
Basic passport data of accessions can be accessed on the Internet. The genus Aeschynomene is distributed across the tropical regions of Africa, South-East Asia, the Pacific Islands and, mainly, South and Central America. Few species are found in warm-temperate regions. The origin of about 50% of Aeschynomene species is in moist-soil environments. However, most species of the series Viscidulae, to which A. histrix belongs, originate from drier environments such as savannas, hillsides and beaches with well-drained soils (Rudd, 1955). The geographic distribution of A. histrix is Central and South America and the Caribbean. It grows up to an altitude of 1400 m asl; two specimens have been collected in Florida. A. histrix is a short day plant (Kretschmer & Bullock, 1980; Bishop et al., 1988).
During the CIAT germplasm collection missions in the 1970s and '80s, A. histrix, together with A. brasiliana and A. paniculata, was collected mainly in habitats characterized by grass and bush savanna vegetation with sandy, acid and low-fertility soils (R. Schultze-Kraft, unpublished). In subsequent evaluation trials all three species showed remarkable adaptation to such marginal soils (CIAT, 1979).
Though not yet adopted, the potential of A. histrix as a pasture legume for well drained soils in drier areas has been recognised since the late 1970s (Kretschmer and Bullock, 1980; Bishop et al., 1988). Experiments in South America and West Africa highlight the high crude protein content, average to good dry matter digestibility, reasonable drought tolerance, and good dry matter production and ability to compete with weeds (Costa et al., 1993; Peters et al., 1994; Tarawali, 1994; Merkel et al., 2000). In West and Central African regional trials with 20 legumes, A. histrix ranked no. 6 in general performance (RABAOC, 1995). Plants are sensitive to frequent cutting (Peters et al., 1994; Giraldo et al., 1985). Relative palatability in small-plot cafeteria trials was low, but after an adaptation phase under grazing, A. histrix was readily consumed by cattle (Peters et al., 2000). Regeneration of A. histrix is mainly from seed as the species is a prolific seeder (see below). Recent studies by Muhr et al. (1999a,b) indicate the potential of A. histrix as a fast decomposing green manure. In Côte d'Ivoire, the species showed good potential for legume fallow on a P fixing Ultisol in the humid tropics (Becker et al., 1998).
Of particular interest for agricultural production systems in West Africa is the ability of A. histrix to act as a trap crop for Striga hermontica, a noxious parasitic weed limiting crop yields (Weber et al., 1995). Merkel et al. (2000) evaluated 60 accessions and found differences in response among accessions in terms of their ability to supress germination of Striga. Subsequently, there is growing interest in A. histrix among farmers in Benin.
In the study of Merkel et al. (2000), comparing a collection of 65 accessions of A. histrix, accessions CIAT 9690 (ILCA 12463), 18539, and 18974 were selected for systems in West Africa, based on agronomic performance, forage quality parameters, seed production and ability to suppress Striga. In regions without the Striga problem, CIAT 7884, 8262, 8581, 8904, 8907, 8911, 8943 were added as promising accessions.
Diseases and pests
The most important disease reported for A. histrix is anthracnose, caused by the fungus Colletotrichum gloeosporioides. In contrast to isolates of the same pathogen from Stylosanthes spp., the isolates from Aeschynomene spp. seem to have a wide host range among legumes (Lenné, 1994). The variability in the pathogen is not well known. Hence the resistance of accessions is unclear. Other reported diseases include Rhizoctonia Foliar Blight (RFB) and Fusarium (Sonoda & Lenné, 1986; Merkel et al., 2000). In the study of Merkel et al. (2000), accessions with prostrate growth habit were more affected by RFB, while semi-erect to erect accessions were more affected by Fusarium.
A. histrix is a prolific seeder. In a collection of 65 accessions average seed production was 92 kg/ha; in some accessions more than 200 kg/ha were harvested (Merkel et al., 2000).
In the study of Merkel et al. (2000), comparing samples of 65 accessions harvested 13 weeks after planting, crude protein (CP) content and in vitro dry-matter digestibility (IVDMD) of leaves ranged from 13-28%, and 45-82 % respectively, while stem samples ranged from 8.5-15% CP and from 30-45% IVDMD. Leaf/stem relation was 1.9:1 to 0.6:1.
Main attributes and shortcomings
Based on experiences which, however, are limited to A. histrix accession CIAT 9690 main attributes are good production of leafy biomass; adaptation to acid and low-fertility soils such as Ultisols and Oxisols; and potential as a Striga trap crop. Main shortcomings are susceptibility to anthracnose and sensitivity to frequent cutting.
Becker M. et al. (1998); Bishop H.G. et al. (1988) ; CIAT (1979) ; Costa N. de L. et al. (1993) Giraldo L.A. et al. (1985); Kalin Arroyo M.T. (1978); Kretschmer A.E. and Bullock R.C.(1980); Lenné J.M. (1994) ; Merkel U. (1996) ; Merkel U. et al.(2000); Muhr L.et al. (1999a) ; Muhr L. et al.(1999b); Peters M. et al.(1994) ;Peters M. et al. (2000) ; RABAOC (1995); Rudd V.E. (1955); Rudd V.E. (1959); Sonoda R.M. and Lenne J.M.(1986); Tarawali S.A. (1994); Weber G. et al.(1995); W3Tropicos