Effects of seed provenance, pre-treatment and mass on germinability and seedling growth of Balanites aegyptiaca (L.) Delile and Ricinodendron heudelotii (Bail.) Pierre in Benin (West Africa)

Balanites aegyptiaca (L.) Delile and Ricinodendron heudelotii (Bail.) Pierre are socioeconomically important species in sub-Saharan Africa. This study was conducted to assess the seed germinability and seedling growth of those species based on several treatments and to define proper conservation and domestication strategies in Benin. The seeds were randomly collected in their natural habitats. The experiment was conducted using a split-split plot design and the data was analyzed using the generalized linear mixed and survival models. The heaviest seeds (B. aegyptiaca seed mass ≥3 g and R. heudelotii ≥ 1.50 g) provided the highest germination rates (73.60 ± 5.19% and 62.50 ± 5.71%, respectively) when seeds were scarified with a hammer. For B. aegyptiaca seedlings, the seeds from the phytodistrict of North Borgou scarified with a hammer and the heaviest seeds showed the highest total height (36.43 ± 1.03 cm), basal diameter (2.84 ± 0.03 mm), the greatest number of leaves (32), and ramifications. The heaviest seeds of R. heudelotii had also the highest value for total height at the day-28 after sowing (26.73 ± 13.56 cm) until the day-105 (151.97 ± 6.37 cm). The heaviest seeds of R. heudelotii from the phytodistrict of Pobe showed the highest basal diameter (12.53 ± 1.47 mm) and the greatest number of leaves (14), with almost no ramification during the trial period. These findings constitute a step forward in upscaling the reproduction of these species for better contribution to economies while serving in restoration plans.