Vegetative propagation of Balanites aegyptiaca (L.) Del., Diospyros mespiliformis Hochst. ex. A. Rich. and Sclerocarya birrea (A. Rich.) Hochst. in northern Cameroon

Introduction. The suckering and the air layering methods of three multipurpose fruit trees, B. aegyptiaca, D. mespiliformis and S. birrea, were studied in Kering (Sudano-Sahelian zone of Cameroon) in order to contribute to the low-cost propagation of these overexploited species. Materials and methods. Three representative stations of this locality (home gardens, bush and river banks) were selected. A study was carried out with 90 trees per species in each of these stations. A preliminary ground investigation under these 90 selected trees per species was carried out to detect natural root suckering or ground layering. Then, the possibilities of induction of suckers at the beginning of the rainy season by partial wounding or complete cutting of roots and the aptitude for air layering at the end of the rainy season were tested on these selected samples. Results and discussion. The S. birrea species presented a high aptitude for natural root suckering compared with the two other species. D. mespiliformis suckered reasonably well, whereas B. aegyptiaca, a much grazed fodder species, showed here a weak aptitude for natural suckering. The station effect on suckering was significant, with a higher frequency of the suckers on the river banks. The natural terrestrial layering was not noticed on the total of 270 trees investigated. The induction of root suckering realised at the beginning of the rainy season by the method of complete cutting of roots appeared more effective after 9 months (mean rate of 57.7% for all species) compared with the method of partial wounding of roots (rate of 37.7%). The light amplified root suckering on stressed roots. Induced suckers generally appeared on the proximal side (near the stem of the mother tree) of the stressed roots, but also on the distal side. Realised at the end of the rainy season, the air layering trials of B. aegyptiaca showed 95% success, whereas the two other species were refractory after 5 months of observation. Conclusion. Besides genetic, physiological and environmental factors that could influence the success of air layering or root suckering of these species, S. birrea and D. mespiliformis were predisposed in this ecosystem to root suckering, while B. aegyptiaca can be easily propagated by air layering. This opens up new ways for the multiplication of these wild fruit-bearing species overexploited by the populations.