Production of Yam Tubers Using Seed Tubers from Vitroplants Regenerated from Aerial Stems in the Yam Species Dioscorea alata (L.) and Dioscorea cayenensis-rotundata (L. & P.) in Côte d’Ivoire

The aim of this study is to produce large quantities of yam tubers in the field from seed tubers derived from vitroplants regenerated from aerial stem cuttings and farmers’ tuber seeds. Seed tubers from ten yam cultivars, including five from Dioscorea alata (cDa083, cDa053, cDa115, cDa150 and cDa266) and five from Dioscorea cayenensis-rotundata (cDr015, cDr027, cDr150, cDr206 and cDr148) with distinct agro-morphological characteristics, were used as material. A completely randomized block design with 3 replications was used. In each block, all cultivars and seed types were represented. When put into cultivation, the tubers produced by the vitroplants all germinated and gave 100% healthy plants, compared with 86% to 100% healthy plants for the seed tubers produced by the farmers. Yields per hectare ranged from 10 to 25 tonnes for seed tubers produced by in vitro plants, and from 4 to 9 tons for seed tubers produced by farmers. Seed tubers from vitroplants can therefore be recommended to farmers as a solution to the problem of seed tuber unavailability.

Morphological Diversity and Distribution of <i>Garcinia kola</i>Heckel (Clusiaceae) in Two Agro-Ecological Areas of Côte d’Ivoire

The purpose of this study is to determine the morphological diversity and distribution of Garcinia kola Heckel (Clusiaceae) in two preferential agro-ecological growth areas in Cote d’Ivoire, for the sustainable management of the species. Ninety-four (94) trees of G. kola were sampled in Affery (south) and Biankouma (west) and characterized on the basis of 13 quantitative characteristics of the fruit, the general appearance of a plant, leaves and seeds. This study revealed the existence of very significant variability and differences within the trees sampled for most characteristics. Very strong correlations were found among the characteristics of the fruits. On the basis of these characteristics, it emerged that the fruits of the Biankouma area are larger than those of Affery. Multivariate analyses show that diversity is structured with tree distribution into four distinct groups based on the following discriminating characteristics: fruit height (Hfr), leaf width (largF), seed mass (Mgr) and trunk diameter (Dm). These parameters can be used as a basis for selecting and maintaining the high variability of G. kola. Analysis of the geographical distribution of trees, based on the nearest neighbour model, revealed an aggregate distribution in both areas.

Spatial patterns of a savanna palm tree Borassus aethiopum and its temporal variability

The spatial distributions and associations of plant species in a stand can provide essential information about their dynamics.However,since tree spatial distribution and association depend on factors that operate at different scales,disentangling the effects of environmental heterogeneity and plant-plant interactions requires the choice of a suitable null model for spatial analysis.We analyzed the spatial distributions of the same savanna palm tree populations that were studied,the underlying hypothesis being that these distributions have changed in 20 years.To remove the effect of large-scale environmental heterogeneity,the inhomogeneous L-function under the heterogeneous Poisson null model was used.We showed:(i)unlike 20 years ago,adults had a regular distribution instead of an aggregated distribution in the grass savanna;(i)although the spatial distribution of seedlings and juveniles was always aggregated,we observed a decrease in the size of the aggregates(intensities);ili)except for juveniles,no other stages were associated with nutrient-rich patches,which was also different 20 years ago;(iv)we did not observe any particular difference in structure between two study sites,only that female palm trees were spatially associated with entire-leafed seedlings in the reserve while they were spatially independent in the rural area.Our study supports the hypothesis that the spatial distributions have partially changed,and that the management of spatial heterogeneity has improved and given more precision in the results.