A preliminary study on the germination of Sclerocarya birrea subsp. caffra

Abstract

Seeds of Sclerocarya birrea (A. Rich.) Hochst. subsp. caffra (Sond.) Kokwaro, commonly known as marula, occur in locules within a hard lignified endocarp. The endocarp appears to restrict germination mainly by offering mechanical resistance. It may also restrict the leaching of germination inhibitors and possibly serve as a barrier to oxygen diffusion. The endocarp does not restrict water uptake. High germination counts were only obtained by removing opercula. Leaching slightly improved germination of seeds in intact endocarps. The optimum germination temperature of opercula-removed seeds was between 27° and 37°C. Storage improved rate of germination. Sade van Sclerocarya birrea (A. Rich.) Hochst. subsp. caffra (Sond.) Kokwaro, algemeen bekend as maroela, kom voor in vrughokke binne ’n harde gelignifiseerde endokarp. Skynbaar verhoed die endokarp saadkieming hoofsaaklik weens die meganiese weerstand wat dit bied. Dit mag ook die uitloging van kiemingsremstowwe beperk en moontlik weerstand teen die diffusie van suurstof bied. Die endokarp beperk nie wateropname nie. Goeie saadkieming is alleenlik verkry na verwydering van operkulums. Loging het die kieming van sade in intakte endokarpe effens verhoog. Die optimum kiemingstemperatuur van sade, na verwydering van operkulums, was tussen 27° en 37°C. Opberging het die tempo van kieming verhoog.