Germination Capacity of Annonaceae Seeds (Annona muricata L., A. squamosa L. and A. senegalensis Pers.) Cultivated Under Axenic Conditions

Despite their socio-economical potential, edible Annonaceae are underused in Senegal. The misuse of their various organs associated with the adverse effects of drought and seasonal bush fires reduce drastically natural regeneration. The limiting factors intrinsic to the seeds also lessen the renewal of stands in the wild. This study was undertaken to evaluate the in vitro germination capacity of Annonaceae seeds and to define the optimal conditions favorable to their germination process. Viability study and germination capacities were undertaken with a focus on seeds stored at 6°C for one month. Various pretreatments such as with bleach, sulfuric acid (95%) solution and complete husking of seeds, were carried out at different temperature levels, in various lightening conditions or in darkness. The best germination percentages were recorded with both seeds scarified mechanically and chemically. Whatever the species, the germination is improved when the pretreatment duration with concentrated sulfuric acid increases. The highest germination rates were obtained at 30 °C for Annona muricata (61%) and A. squamosa (74%) and at temperature levels of 27 °C and 30 °C for A. senegalensis (59%). The A. squamosa seeds, previously scarified with absolute sulfuric acid for 60 min, better germinated in darkness (69%) than under illumination (46%) in contrast to those of A. senegalensis (58% in the light and 44% in the dark) and of A. muricata (63% in the light and 32% in the dark).