Developing sustainable regeneration techniques for four African mahogany species: grafting methods for success and growth

Development of planting materials through vegetative propagation has been difficult in some timber species due to ontogenetic aging which slows down rooting of stem cuttings. Applying grafting techniques helped produce quality planting materials with unique characters, as these techniques influenced union establishment and successful growth of the grafted plants. This study assessed effects of different grafting techniques on establishment and early growth of four African mahogany species (Khaya ivorensis, K. anthotheca, K. grandifoliola and K. senegalensis) using 2-year old seedling rootstocks and scions from mature trees with desirable stem form. We assessed effects of three grafting methods (top-cleft, side grafting, and whip and tongue), and scion type on growth performance of the African mahogany species at 6 months after grafting. K. grandifoliola scion grafted onto K. grandifoliola rootstock recorded highest mean graft success (81.67%), number of leaves formed (11.6) and shoot height growth (7.47 cm) in the top-cleft method. The whip and tongue method was least successful among the three methods. Homografted plants had greatest influence on the grafting parameters for highest mean successes in K. grandifoliola/K. grandifoliola (81.67%), K. anthotheca/K. anthotheca (73.33%) and K. senegalensis/K. senegalensis (63.33%) except K. ivorensis scion type which occurred in the heterograft K. grandifoliola/K. ivorensis (76.67%). Highest performance of the top-cleft method is attributed to good contact between cambia of the grafted species and thus their easy union and growth. Grafting of the four African mahogany species is most successful using top-cleft grafting technique for sustainable production of improved cultivars for restoration and conservation.