Centrosema rotundifolium is an amphicarpic wild legume whose potential as pasture species on acid soils of low fertility in the semi-arid to dry-subhumid tropics has been recognised only recently. Amphicarpy, i.e. the ability of the same plant to produce both above- and below-ground seeds, contributes to the regeneration potential of plants from the soil seed bank and thus to the persistence of a plant population in a pasture. Little is so far known concerning the mechanism of amphicarpy in a perennial plant and the effect of environmental factors on the balance between below-ground and above-ground reproduction. In the project, the influence of various environmental stress factors on the resource allocation is investigated on a sandy soil of low fertility in East Venezuela, a site that is representative for neotropical savanna regions. The factors under study are intraspecific competition (plant density), interspecific competition (associated grasses), intensity of defoliation (forage utilisation), fire and fertilization.