Influence of morphological characteristics of fruits and provenances on seedling emergence and early growth in Detarium microcarpum Guill. & Perr. and Detarium senegalense J.F. Gmel. (Fabaceae) in Benin.

Detarium microcarpum and Detarium senegalense are multipurpose tree species native to Africa. The plant parts of these species are overexploited leading to the decline in their natural populations. This study assessed the possibility for seed-based propagation of these species. Specifically, the aims were to identify their fruit morphotypes in the phytodistricts of Bassila and Borgou-Sud (Sudano-Guinean zone of Benin) and to assess the influence of the fruit morphotypes and their provenances on seedling emergence and early growth parameters. A total of 2400 and 330 fruits were collected for D. microcarpum and D. senegalense respectively and characterised based on five morphological descriptors. Hierarchical clustering was used to group fruits in morphotypes with similar characteristics. A randomized complete block design with three replicates was used for the trial on seedling emergence and early growth for each species and for 182 days. A linear mixed model on longitudinal data was applied on seedling emergence and early growth data. Three fruit morphotypes were identified for D. microcarpum and two morphotypes for D. senegalense. Morphotypes 2 of both species were those which gave the highest seedling emergence rates (88.33% for D. microcarpum, and 50% for D. senegalense). Considering the provenances, the best seedling emergence performances were observed for seeds from the Borgou-Sud district (93.89% in D. microcarpum and 39.17% in D. senegalense). Also, these seeds were those which gave the highest values of growth parameters. Morphotypes 2 of both species gave the highest values for total height and number of leaves. This study revealed that Borgou-Sud morphotype 2 for each of the two species constitutes potential candidates for domestication programs.