Genetic differentiation in leaf phenology among natural populations of Adansonia digitata L. follows climatic clines

Leafing phenology is an important component of climatic adaptation in semi-arid regions. The questions are to what extent phenology is under genetic control and represent adaptation to local climates? In the present study, we compare leaf phenology among Adansonia digitata L. trees of 27 different origins from West and East Africa and test if the differences follow climatic clines. Timing of bud burst was largely synchronized with the start of rainy season, but some few individual trees showed bud burst before the first rain. Timing of leaf senescence was under genetic control with substantial differences among origins. The timing of senescence was for some origins at the end of rainy season and for some in the beginning of the dry season. Differences among origins in timing of leaf senescence were related to the variation in drought just before- and in the first months of the rainy season at the sites of origin. Populations from drier sites had the earliest leaf shed at the common test site indicating that trees have been adapted to the prevailing climatic conditions at the sites of origin. We discuss the results in the light of possible triggering factors. Keywords: Baobab, Geographic variation, Phenological phases, Senescence, Budburs

Variability of vitamins B1, B2 and minerals content in baobab (<i>Adansonia digitata</i>) leaves in East and West Africa

The regional variability and age–age correlation on vitamin B1, vitamin B2 and minerals (Ca, Mg, P, K, Cu, Fe, Mn, Na, and Zn) concentration in baobab leaves were investigated. Baobab was cultivated from seeds from 11 countries including Benin, Burkina Faso, Kenya, Malawi, Mali, Mozambique, Niger, Tanzania, Togo, Senegal, and Sudan. Vitamins B1 and B2 content were assessed using microbiological VitaFast kits methods and minerals by atomic absorption and flame spectrometry methods. Overall, the results showed a higher content of vitamin B2 compared to vitamin B1 with the highest vitamin B2 content (1.04 ± 0.05 mg/100 g DM) from Senegal. The highest iron (Fe) content of 26.39 mg/100 g was found in baobab leaves from Mali. For age–age correlation, adult baobab leaves of Nankoun in Burkina Faso provided the highest calcium (Ca) content of 3373 mg/100 g. However, for provenance trial, young plants from three communities of Burkina Faso showed the highest calcium (Ca) and potassium (K) content. The study demonstrated that vitamins B1 and B2 and mineral contents in baobab leaves vary with the country and the age of the tree. Vitamin B1 content was higher in baobab leaves from ascendants compared to those from descendants, while in contrast vitamin B2 content was higher in the leaves from the descendants compared to their ascendants (mother tree)