Elie A. Padonou

Differences in germination capacity and seedling growth between different seed morphotypes of Afzelia africana Sm. in Benin (West Africa)

Summary Afzelia africana is a multi-purpose woody species threatened by a lack of natural regeneration in the wild. In the present study, differences in seed germination capacity and seedling growth between morphotypes of the seeds of A. africana Sm. were evaluated. A total of 600 seeds were collected in the Sudanian and Guinean climatic zones of Africa and their lengths, widths, thicknesses, and weights were recorded. A hierarchical classification and canonical discriminant analysis were applied to the above traits of seeds from the different climatic zones. An analysis of variance with repeated measures was applied to seed morphotypes identified by hierarchical classification to test for the effect of these morphotypes on seed germination and seedling growth. Hierarchical classification helped to identify three seed morphotypes. Canonical discriminant analysis performed on these morphotypes revealed highly significant differences. Morphotype 1 consisted of seeds from the Guinean zone, while seeds from the Sudanian zone were clustered in morphotypes 2 and 3. Morphotype 1 had the longest and heaviest seeds, while the shortest and lightest seeds were from morphotype 3. Morphotype 1 and morphotype 3 seeds showed rapid germination, while only morphotype 1 seedlings displayed rapid growth. Morphotype 1, consisting of large seeds, was superior in terms of its germination ability and seedling growth, and represents the best choice for species restoration purposes.

Natural variation in fruit characteristics and seed germination of Jatropha curcas in Benin, West Africa

Summary An investigation was conducted in the ten phytodistricts of Benin, West Africa, in order to assess the level of morphological variation in Jatropha curcas seed and their germination potential. Hierarchical classification of the morphological traits of seeds identified five morphotypes, using 54% of the overall morphological information. Canonical discriminant analysis performed on the five morphotypes revealed highly significant differences. Morphotype 1 included seeds from the phytodistricts of Côtier, Pobè, The Ouémé Valley, and Plateau. Morphotype 2 and Morphotype 5 seeds were from the phytodistricts of Bassila, Zou, and Borgou-Sud; while Morphotype 3 and Morphotype 4 seeds were from the phytodistricts of Borgou-Nord, the Atacora Chain, and Mekrou-Pendjari. Significant morphological variation existed within the seeds as a consequence of genetic make-up and/or environmental effects. Seed from Mekrou-Pendjari and the Atacora Chain were black, smooth, light (0.67 g seed–1), and small (1.76 cm-long and 1.15 cm-wide). Seed from Plateau, Côtier,The Ouémé Valley, and Pobè zones were brown, rough, heavy (0.84 g seed–1), and large (1.97cm-long, 1.2 cm-wide). All seed germination started 4 d after sowing and ended between day-7 and day-8. Seed germination timing varied significantly with morphotype.