Variability of the morphological characters of Balanites aegyptiaca (L.) del. based on the climatic gradient of Zinder Region (East-Central Niger)

This study, carried out in the centre-east of Niger, aims to analyse the variability in morphological characteristics of Balanites aegyptiaca, based on the climatic gradient. Thirteen (13) morphological descriptors were defined and used to characterise the natural populations of B. aegyptiaca. They concerned measurements on the morphological aspects of the leaves, thorns and fruits of six (6) spontaneous populations of Balanites aegyptiaca. For each population of B. aegyptiaca, a random selection of 30 individuals carrying fruits was made. On each individual, measurements were made on 10 fresh leaves, 10 fully developed thorns free from parasites, and 10 ripe fruits showing no signs of physical damage. In total, 1800 fruits, 1800 leaves and 1800 thorns coming from 180 individuals of Balanites aegyptiaca were subjected to measurements. The results of the study showed that populations from the sahelo-sudanian zone are characterised by heavy and big fruits, long leaflets and petioles, and thorns with large diameters. Those from the strictly sahelian zone were characterised by large endocarps and a thick pulp. Those from the sahelo-saharian zone were especially characterised by long thorns. This study has demonstrated the morpholoigcal variability of populations of Balanites aegyptiaca according to the climatic gradient, confirming the adaptability of the species in relation to the climate’s aridity. This ability to adapt explains the wide ecological dispersion of the Balanites aegyptiaca. The current study is a contribution to an improved understanding of the different morphotypes of Balanites aegyptiaca, and constitutes a step towards the domestication of the species.