Identification of determining traits of seed production in Carapa procera and Pentadesma butyracea, two native oil trees from riparian forests in Burkina Faso, West Africa

Natural resources are of vital importance for populations of African rural communities. Native oil trees are sources of promotable products for which the natural resource availability is urgently needed. The present study aims to assess the seed production of two oil tree species, Carapa procera and Pentadesma butyracea to identify traits related to seed production. Seeds were collected from 77 trees of C. procera and 36 trees of P. butyracea and, stem diameter, height and crown diameters were measured. Ten mature fruits per tree were collected randomly and seeds were extracted, counted, dried and weighed to obtain dry weight. Analyses of variance were performed to test for differences in seed production between years and between size classes of trees. To predict seed production, best subsets regression was used to perform predictive allometric equations by selecting tree size variables for appropriate models. The seed production per tree of C. procera and P. butyracea was 1-11 kg depending on tree size. For both species, there was a significant variation (p < 0.05) among stem diameter classes, with the highest seed weight found in the >50 cm classes. Seed production did not vary significantly between years. The regression equation models performed for the prediction of seed production in both species were statistically significant (p < 0.05). They showed high goodness-of-fit (R2 > 70%) and revealed good predictive accuracy for new observations. The predictive equations established are useful tools for the planning of rational seed exploitation for both native oil trees.