Clonal propagation of Detarium microcarpum and Khaya senegalensis

The slow growth of seedlings and the impact of insect pests are major limitations to the use of indigenous species in plantations in Burkina Faso. Thus, the use of vegetative propagules and resistant clones may enhance the success of plantations. The objectives of this thesis were to develop efficient and simple clonal propagation methods for two indigenous species, Detarium microcarpum and Khaya senegalensis, and to compare the growth of sexual and asexual propagules. Two clonal propagation methods were developed: root cuttings for D. microcarpum and stem cuttings for K. senegalensis. Root segment length and diameter were key factors that affect sprouting and rooting ability. Root segments of 20 cm length and 15-60 mm diameter were the most successful. Stockplant and auxin application influenced root formation by leafy stem cuttings of K. senegalensis. High proportions of cuttings taken from seedling have rooted, while cuttings obtained from older trees rooted poorly, highlighting maturation as critical factor. The rooting ability of cuttings from older trees was improved by pollarding and auxin application. Comparison of sexual and asexual plantlets of D. microcarpum revealed that root suckers and seedling sprouts had a closer morphological resemblance. The well-established root system and the high carbohydrate concentrations in the roots of seedling sprouts may favor a growth comparable to that of root suckers. Seedlings and stecklings of K. senegalensis had similar growth patterns with respect to: the relative growth rates of stem length, leaf, stem, root and the total plant biomass; the biomass fraction to total plant biomass of leaf, stem and root; leaf area productivity; foliar carbon isotope ratio; and carbohydrate concentrations in roots. However, water stress was a major growth-limiting factor, resulting in a reduction in plant growth, biomass production, and carbohydrate concentration. As these studies constitute a first step toward the effective use of clonal propagules of D. microcarpum and K. senegalensis to ensure successful plantation, more investigations examining the effects of donors, the application of plant growth regulators are required in order to optimize the techniques