Domestication Potential of Garcinia kola Heckel (Clusiaceae): Searching for Diversity in South Cameroon

Seeds and bark of Garcinia kola Heckel (Clusiaceae) are popular products in West and Central Africa. Despite the tree's economic and cultural importance, little is known about its phenotypic and genotypic variation. This study characterised the morphological and genetic diversity of G. kola in South Cameroon, searching for traits and populations that might be used for domestication. Morphological assessment and amplified fragment length polymorphism (AFLP) markers were applied to characterise diversity among geographic populations from Central and South regions, and between managed and wild trees. AFLP-SURV and analysis of molecular variance results indicated that a major part of genetic diversity is harboured within populations rather than between them. Bayesian analysis, principal component analysis and t-SNE identified three clusters where Ebolowa emerged as the transition population combining features from both regions. Trees from the South demonstrated a higher incidence of domestication-related traits, showing higher genetic diversity compared to the Central region. This suggests that individuals from the South might be more suitable for selection as "elite trees" in future breeding strategies for the species. No significant differences in phenotype and genotype were revealed between wild and managed populations, suggesting G. kola is still in the early stages of its domestication process

Improving growth of stockplants and rooting ability of leafy stem cuttings of Allanblackia floribunda Oliver (Clusiaceae) using different NPK fertilizers and periods of application

Our study addressed the effect of granular NPK 20-10-10 doses (0, 25 and 50 g/plant) applied to A. floribunda stockplants on growth of stockplant and the effect on rooting ability of foliar NPKs (15-15-30, 20-20-20 and 30-10-10) applied on leafy stem cuttings in propagators at different physiological stages of rooting process (setting, callus initiation and both). Results show that fertilizer doses significantly (p = 0.03) affect the number of cuttings that could be produced by stockplants 6 months after application. The mean number of cuttings per plant increased with fertilizer doses with the highest value of 11.06 +/- 0.41 % for 50 g. Application of NPK 20-20-20 foliar fertilizer on stem cuttings at callus stage, significantly (p = 0.04) boosted rooting of stem cuttings after 28 weeks (85.71 +/- 4.1 %). Number of roots per cutting was not significantly different (p = 0.98). However, the highest frequency of cuttings displayed three roots was observed on NPK 20-20-20 (To + Cal) and NPK 30-10-10 (To + Cal). From this study, we can conclude that, 50 g of NPK 20-10-10 fertilizer application on stockplants produced the greatest number of vegetal material. Treated with NPK 20-20-20 at callus initiation stage or both (i. e. at setting and at callus initiation stage), rooting performs better

Variation phénotypique des fruits des écotypes de Dacryodes edulis (G. Dom) H.J. Lam récoltés dans trois zones agro-écologiques de la République Démocratique du Congo

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Nursery substrates and provenances influence rooting performance of juvenile, single-node vine cuttings of Gnetum africanum Welw. (Gnetaceae)

Gnetum africanum Welw. (Gnetaceae) is a forest vine that is highly valued for its leaves which are a source of food and income. Because wild populations are threatened by over-harvesting, there is an increasing need to cultivate the plant, which in turn entails a need for developing good quality planting material. This study investigates the effects of four provenances, four substrates and their interactions on rooting and shoot development of vine cuttings of G. africanum using the non-mist propagation system developed by ICRAF. Single-node, half-leafed vine cuttings were used and data on rooting and leaf production were collected monthly from the second to the fifth months. Rooting percentages were subjected to analysis of variance using logistic regression procedures in Genstat version 12. Provenance (P<0.001), substrate (P<0.001) and interaction between provenance and substrate (P<0.001) showed highly significant effects on rooting. Excel was used to determine rooting percentages, with the highest observed in fine sand on cuttings from Lekie-Assi (81%) and Boumnyebel (79%) which are high G. africanum exploitation areas in the Centre Region of Cameroon. Boumnyebel showed a significantly higher shoot development than the other provenances. Fine sand and sharp sand can be recommended for rapid, low-cost production of G. africanum planting material

Allanblackia floribunda: a new oil tree crop for Africa: amenability to grafting

Three Allanblackia species (A. floribunda, A. stuhlmannii and A. parviflora) with high nutritive, medicinal, cosmetic and economic values are currently being domesticated as new oil tree crops. Allanblackia seeds contain a hard white fat consisting mostly of stearic (52-58%) and oleic (39-49%) acids. This unusual fatty acid content has the right properties for many different food and cosmetic products making them commercially interesting. Vegetative propagation studies on A. floribunda, which grows naturally in the moist forest of Cameroon and Nigeria, were initiated aimed at evaluating its amenability to grafting. Scions were grafted onto 18 month old rootstocks of A. floribunda using side tongue, top cleft, side veneer, whip-and-tongue methods under nursery conditions in Cameroon. In parallel, side tongue and inverted 'T' budding methods were also tested in situ on young A. floribunda wildings growing under semi-deciduous and evergreen tree covers. In addition, the effects of protecting side tongue new grafts with non perforated translucent plastic, perforated translucent plastic and aluminium foil were assessed. Under nursery conditions, side tongue grafts were significantly more successful (80.0 +/- A 6.3%), than grafts of side veneer (52.5 +/- A 7.9%), top cleft (55.0 +/- A 7.9%) and whip and tongue (50.0 +/- A 7.9%). The success of side tongue graft was further increased (86.7 +/- A 6.2%) under the shade of evergreen trees when protected by non perforated translucent plastic. These results indicate the potential for in situ grafting and 'top working' to promote cultivation of more productive germplasm of Allanblackia within multifunctional agricultural systems