Diversité morphologique des fruits et discrimination d’écotypes potentiels de Hyphaene thebaica dans la vallée de Goulbi N’Kabba (Maradi, Niger)

An emblematic species of the Sahelian agricultural landscape, the doum palm (Hyphaene thebaica Mart.) is widely distributed across Niger's agroecological zones, where it structures landscapes and diversifies local populations' livelihoods. Despite its ecological and socio-economic importance, scientific knowledge of its intraspecific diversity remains limited. Existing work on this species has mostly focused on ethnobotany, species ecology, and harvesters' practices, while integrated assessment of the morphological and biochemical variability of its fruits remains at an early stage at the local and regional levels. It is against this backdrop that the present study characterized the morphological variability of H. thebaica fruits in order to identify the morphotypes present in the Goulbi N'Kabba valley (Maradi, eastern Niger). A sample of eleven morphotypes was identified on the basis of the relative homogeneity of their shape and volume at three collection sites near this valley. For each morphotype, five mother trees at least 50 m apart were identified; from each mother tree, five fruits were randomly harvested, for a total sample of 275 fruits. On each fruit, seven variables were measured — length, width, total weight, mesocarp weight, shell weight, kernel weight, and volume — then compiled in Excel and analyzed using Past 4.0 software (Kruskal-Wallis, Mann-Whitney, and Duncan/Tukey tests, and multivariate analysis: PCA + HCA). PCA accounted for 75.7% of the variance on the first two axes, and all variables significantly discriminated between morphotypes (ANOVA, p < 10⁻⁷), with kernel weight (F = 58.3) followed by volume (F = 53.6) being the most discriminating morphometric descriptors; HCA (Ward's method) confirmed a structure broadly consistent with this typology, although the optimal agreement (ARI = 0.49) was reached around nine groups, with some neighboring morphotypes remaining morphologically close. These results, statistically well founded at the univaria.