Luis Horacio Franco

Phenological, agronomic and forage quality diversity among germplasm accessions of the tropical legume shrub Cratylia argentea

SUMMARYCratylia argentea (Desv.) O. Kuntze is a drought-tolerant tropical shrub legume that can helpto ensure continuity of forage supply in smallholder systems either through direct grazing or as acut-and-carry plant for fresh foliage or silage. A collection of 38 accessions was characterized agro-nomically and nutritionally. High diversity was detected between accessions. Time to floweringranged from 217–329 days after transplanting seedlings to the field and from 129–202 days aftercutting. Flowering is probably induced by reduction of day length. Seed production was high butvariable. Dry matter production ranged from 190–382 g/plant in the rainy and from 124–262 g/plantin the dry season, content of in vitro digestible dry matter from 589–690 g/kg, crude protein contentfrom184–237g/kgandfibrecontentfrom403–528 g/kg(neutraldetergent fibre,NDF),240–335 g/kg(acid detergent fibre, ADF), and 9–13 g/kg (acid detergent fibre-bound nitrogen, N-ADF).Accessions CIAT 18674 and CIAT 22406 were identified as promising for further study. They weresuperior to the commercial cultivar in terms of dry matter (DM) production, particularly in the dryseason. Further research is required to determine the prevailing reproduction strategy of C. argenteaand to quantify outcrossing-rates. Multilocational trials with a selected set of accessions should beconducted under different environmental conditions.INTRODUCTIONLivestock productivity in the tropics is severelyaffected in the dry season by low availability andquality of fodder (NAS 1979; Ranjhan 1986;Enri´quez et al. 2003). High-protein legumes, in par-ticular shrub species, can contribute to improvedproductivity of livestock during dry seasons and atthe same time maintain and even restore soil fertility(Brewbaker 1986; Schultze-Kraft & Peters 1997;Peters et al. 2001; Shelton 2001). Cratylia argentea(Desv.) O. Kuntze (syn. C. floribunda Benth., Diocleaargentea Desv.) is a shrub legume which was selectedas promising for dry-season supplementation, par-ticularly in regions with acid soils and extended dryseasons(Argel MArgelLPeters & Schultze-Kraft 2002).Cratylia argentea belongs to the familyLeguminosae, subfamily Papilionoideae, and is themostwidely distributed ofthe fivespecies in the genus(de Queiroz & Coradin 1996; Pizarro et al. 1997). Theleafy shrub usually reaches 1.5–3 m, but there aretrees up to 10 m tall. It is found in a broad range ofhabitats from Western Peru to the state of Ceara´ inBrazil, and is well adapted to acid soils of low tomedium fertility and altitudes up to 1200 m asl(Xavieretal.1995;Maass1996;Schultze-Kraft1996;Peters & Schultze-Kraft 2002). Its nutritive value ishigher than thatof most other shrublegumes adaptedto acid soils. Plants contain only trace amounts oftannins(Lascano1996;Shelton2001).Ithasexcellentregrowthcapacityaftercuttingandcanbeusedassoilcover, mulch and green manure. The species is verydrought tolerant and remains green and productive