For arid zones such as the Sahel, drought is one of the most important constraints to the survival and development of plants playing a key role in the livelihoods of human populations. The domestication of fruit trees such as Adansonia digitata and Parkia biglobosa for the Sub-Saharan region has been suggested as a strategy to improve local population livelihoods. The present thesis studies the adaptive properties to drought stress of A. digitata and P. biglobosa at nursery level, two species native to African savannas.

Nursery trials were established with seeds of seven provenances of each of the two species. Three water regimes were applied, corresponding to 100%, 75% and 50% of field capacity. The effects of drought stress on the seedling survival, growth and dry matter partitioning was investigated on both species, and for A. digitata the experiment also included seedling morphology and physiology.

A. digitata had a much higher survival rate than P. biglobosa. However, both species showed a strong reduction of the relative growth rate (diameter and height) and the total dry weight under the effect of applied water stress. Despite differences between provenances of P. biglobosa, it was not possible to link their geographical position or climatic parameters to growth performance, fresh to dry weight or shoot to root ratios. Although some morphological parameters were correlated with the rainfall for A. digitata, none of the physiological differences between provenances were correlated to environmental parameters of the site of origin. However, the provenance from East Africa was in several aspects different from the West African provenances.

For none of the species, there was correlation between the studied parameters and the performance under stress. Therefore provenance recommendations for planting based on the results can hardly be given, other than to use extreme caution if provenances from East Africa are introduced to West Africa, in the case of A. digitata. Until a better understanding of the two species morphology and physiology under drought stress has been achieved, there seems to be no alternative to field testing.