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

Abstract Balanites aegyptiaca (L.) Delile and Ricinodendron heudelotii (Bail.) Pierre are socioeconomically important but endemic species to sub-Saharan Africa. This study was conducted to assess the germination capacity of their seeds and seedling growth according to seed provenance, seed mass and pre-treatment techniques as a contribution to the development of strategies for their conservation and domestication in Benin. The seeds were randomly collected in the species occurrence phytodistricts. A split-split plot design with three replicates was used. The survival analysis and generalized linear mixed effects models were implemented on the data. Findings were that 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%) with seeds scarified with a hammer first emerging at day-8 and day-10 for B. aegyptiaca and R. heudelotii respectively. For B. aegyptiaca seedlings, the seeds from North Borgou phytodistrict 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 (1). The heaviest seeds of R. heudelotii showed also the highest total height from the day-28 after sowing (26.73 ± 13.56 cm) until the day-105 (151.97 ± 6.37 cm) and those from Pobe phytodistrict 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 towards upscaling the reproducibility of these species for better contribution to economies while serving for restoration plans.