Improvement of Seed Germination and Seedling Growth of African Rosewood (Pterocarpus erinaceus Poir) by Seed Pretreatment, Seedling Substrate and Growing Medium

Abstract

Pterocarpus erinaceus is a highly valuable species endemic to West Africa. In Côte d'Ivoire, it is subject to abusive and illegal exploitation, compromising the survival of stands and, above all, its natural regeneration. The aim of this study was to determine the optimum conditions for the germination and development of Pterocarpus erinaceus seedlings in the nursery. The experiment was conducted at the experimental site of the botanical garden of the Peleforo GON COULIBALY University (UPGC) following a randomized Fisher block design with three replications between May and August 2024. Four pretreatments were applied to Pterocarpus erinaceus seeds sown on two substrates in two environments. These were pretreatments (hulled seed, unhulled seed, unhulled seed soaked in ordinary water for 24 hours and hulled seed soaked in ordinary water for 24 hours), substrates (black earth and potting soil) and environments (tunnel and shade). The results showed that hulled seeds grown on sterilized black soil under tunnel conditions showed the best germination rate (81.67%) within a germination time of 3 days with a mean germination time of 7 days after sowing (DAS). These were followed by hulled seeds sown on black soil under shade conditions, with a 76.66% germination rate within a germination period of 3 days and an average germination time of 7.51 days after sowing. The seedlings obtained from these hulled seeds had a height of 20 cm, 7 leaves and a diameter of 1.45 mm in two months in the nursery under tunnel conditions, compared with 14.96 cm in height, 6 leaves and a diameter of 1.95 mm under shade conditions, which considerably reduced the time taken in the nursery compared with previous work. Thus, the technique of hulled seeds grown on black soil under tunnel conditions can be recommended for germinating Pterocarpus erinaceus seeds for planting purposes.