How does seed size of Arachis pintoi affect establishment, top-growth and seed production?

Abstract

The adoption of Arachis pintoi in mixed pastures in the humid tropics remains limited to specific success cases, mainly because of high seed cost. The search for methods to reduce these costs is a key challenge towards promoting wider adoption of this legume in livestock production systems in the tropics. One possible option is to select for smaller seeds, which would allow lower sowing rates, while ensuring similar plant numbers. Alternatively, high seed production costs could be offset by utilizing forage from seed production fields for hay or silage prior to seed harvest. This study evaluated the effects of seed size on crop performance of A. pintoi cv. BRS Mandobi in a tropical forage + seed production system, plus the effects of harvesting forage during the growth stage on seed production. Parameters measured were: ground cover, height, pest and disease incidence, total forage and leaf yield plus seed yield and seed sizes. Smaller seeds resulted in morphologically smaller plants and lower forage mass during the initial phase of crop establishment. However, seed size had no effect on ground cover at the end of the establishment period or on seed production and quality. Harvesting forage during the growth cycle had no effect on seed production. This indicates the possibility of harvesting forage from seed crops of A. pintoi during growth without jeopardizing seed yields as a means of offsetting high costs of seed production. However, the study has failed to provide conclusive evidence whether variation in seed size in BRS Mandobi is mainly genetic or a response to micro-environmental conditions. Further studies with individual plants from BRS Mandobi are necessary to determine the heritability of seed size.