Interactive Effects of Substrate and Length on the Ability of Root Segment Cuttings of <i>Burkea Africana </i>(Hook)<i> and Uvaria Chamae</i> (P. Beauv)<i> </i>to Regenerate

Abstract

The Guinean Savanah Highlands of Adamawa is replete with multipurpose tree species, among which <i>Burkea africana and Uvaria chamae</i> are particularly noteworthy. Despite their importance, they remain in the wild and are subjected to overexploitation. The present study aims to contribute to the domestication of these species by root segment propagation. Specifically, the study aims to evaluate the seasonal variations in carbohydrate reserves (starch, soluble sugars, and sucrose) in other to determine the most favorable period for root cutting collection, assess the effect of substrate and length of root segment cuttings on the budding and rooting capacity of these species, evaluate the effect of carbohydrate content on bud emergence, root formation, callus induction, and control response in cuttings. For the seasonal fluctuation of carbohydrate, the experimental design was a complete randomized design with one factor represented by the season, and two replications. In the case the root propagation, the experimental design was a split-plot with three replications. The main treatment comprised three substrates (sand/sawdust, black soil/sawdust, black soil), while the sub-treatments were represented by three lengths of root segments cuttings (RSC) (10, 15, 20cm). The experimental unit consisted of 10 cuttings. Results showed that the onset of the rainy season coincides with peak of starch, soluble sugars and sucrose for <i>Burkea africana </i>and <i>Uvaria chamae</i>, marking the most favorable period for root cutting collection. The budding rate of <i>Burkea africana</i> showed significant variation (0.04 < 0.05), with values of 2.22 ± 1.96% in a black soil/sawdust mixture and 14.44 ± 12.36% in black soil after 26 weeks. For <i>Uvaria chamae</i> the best substrate was the mixture of black soil/sawdust (63.33 ± 45.27%). The number of leaves for <i>Burkea africana</i> was substantially higher in black soil (4.27 ± 2.16). The difference was statistically significant (0.008 < 0.01). For <i>Burkea africana</i> and <i>Uvaria chamae</i>, the optimal cutting length for budding was 20 cm (11.11 ± 10.52%, 81.11 ± 26.20%). The rooting rate of <i>Uvaria chamae</i> exhibited considerable variability the best rate was those of the black soil/sawdust substrate (22.22 ± 20.33%). The rooting rate varied from 5.55 ± 4.26% for cuttings of 10 cm to 23.33 ± 21.79% for those of 20 cm.Budded cuttings clustered with soluble sugars and sucrose. Rooted cuttings correlate negatively with all carbohydrate. Control cuttings were closely associated with starch. All these informations are important to develop scales and strategies toward the domestication of this species.