Morphological and genetic diversity of wild and domesticated populations of njansang (Ricinodendron heudelotii) (Baill.) Heckel in Cameroon

Bc. Martin Smetana

Master's thesis

Abstract:

Ricinodendron heudelotii (Baill.) Heckel (Euphorbiaceae) is a multipurpose tree species native to humid tropical forests of sub-Saharan Africa. The species is most valued for its oily kernels, which are an important source of food and income for many communities in West Africa, including Cameroon, where the kernels are known as njansang. The main goal of this study was to gather more information on the intraspecific variability of populations of R. heudelotii from different geographical sites in Cameroon and acquire insight of the local ethnobotanical knowledge of the species. This was achieved in 3 objectives. In the first one, intraspecific diversity of R. heudelotii was assessed by measuring morphological characteristics of, in total, 380 fruits and 696 seeds collected from 50 trees coming from 4 different sites in Cameroon. The resulting data did not show statistically significant difference between the 3 populations from sites found in the South region (Vallée-du-Ntem division), while the population found in the Centre region (Nyong-et-Mfoumou division) did differ significantly in terms of fruit length and seed weight. Thus, the second objective was accomplished through principal component analysis of the morphological data which showed the existence of 2 well-defined populations, 1 in each geographical region, while suggesting great variability within the populations as well. The third objective was done by questioning the local farmers, 31 in the South region and 35 in the Centre region. The ethnobotanical information provided insight into management and importance of the species to local communities. It is evident that R. heudelotii is of great value and there is interest in increasing cultivation and production of its kernels, although there are still certain obstacles delaying the domestication efforts. Further research on the species, especially in the field of genetics, and close cooperation with the local communities and researchers seems vital for achieving a successful outcome.

Keywords

genetic diversity, morphology, Farming practices, R. heudelotii, njansang

Language used: English

Date on which the thesis was submitted / produced: 24. 4. 2023

Thesis defence

• Supervisor: prof. Ing. Bohdan Lojka, Ph.D.
• Reader: Naji Sulaiman, externi

Czech University of Life Sciences Prague

Faculty of Tropical AgriSciences

Master programme:
Tropical Crop Management and Ecology