Ecophenotypic variation of fruits, natural seed germination and seedling growth of Picralima nitida in Dahomey Gap: implication for conservation and valorization

Abstract

Picralima nitida is an important African medicinal plant species threatened in the Dahomey Gap. It is used in pharmaceutical industries and traditional medicine to treat several diseases. Despite its importance, this the species faces a serious conservation problem. It is rare, especially in the Dahomey Gap countries in contrast to the Guinean zone. The present study aims to contribute to the conservation of P. nitida by assessing the ecophenotypic variation of the fruit, natural seed germination and seedling growth. A total of 1,200 fruits were collected in two phytodistricts of Dahomey Gap to evaluate the morphotypes. The seeds were evaluated for natural germination with different substrates. The results on ecophenotypic variation and natural seed germination revealed no significant difference (p > 0.05) between the fruits from the two phytodistricts. However, three morphotypes of fruits were obtained with significant difference (p < 0.05). Morphotype 1 gathered large, round and heavy fruits, morphotype 2 fruits were elongated oval-shaped, and morphotype 3 fruits were short, round and light. The highest germination rate (73.33%) was obtained with morphotype 1 seeds on the substrate composed of 100% top soil. The fruits from the phytodistrict of Pobe had seeds with the highest rate of germination (55.55%) on the substrate composed of 100% top soil. The use of organic matter in the substrate of germination stimulated the growth of P. nitida seedlings after seed germination.