Biophysical characterisation of Dacryodes edulis fruits from three markets in Cameroon

Studies were done in order to assess variation in fruit size and weight, nut size and weight and determinate relationships between these characteristics and price using 149 samples of Dacryodes edulis fruits from three markets at the peak of season in Cameroon. 50 samples per market in two markets (Mfoundi market [Yaonde] and Makenene centre market) and 49 samples in Makenene East market were bought randomly from traders. The measurement of 10 characteristics of 24 fruits per sample identified significant variation in fruit size and weight and nut weight in each market. Fruit price was found to vary with flesh mass, fruit mass and fruit size in retailers markets while wholsalers don't take into account fruit variability. In contrast, pulp price per kg was negatively correlated with flesh weight in wholesalers' markets. The most frequent skin colour was "georgetown lime" (29A7 in the Methuen colour code) and the most frequent flesh colour was violet (18D6 in the Methuen colour code). From this study, Dacryodes edulis fruit ideotype fetching highest price in the retailers markets is characterized by length, flesh and fruit mass and white skin colour

Domestication of Dacryodes edulis in West and Central Africa: characterisation of genetic variation

New initiatives in agroforestry are seeking to integrate trees with marketable products into farming systems. This is being done in order to provide marketable timber and non-timber forest products from farms that will enhance rural livelihoods by generating cash for subsistence farmers. Dacryodes edulis (Safou) is one of the candidate tree species in West and Central Africa for domestication, which has commercial potential in local, regional or even international markets. This paper describes: (i) the characterisation of tree-to-tree variation in fruit traits and the opportunities for selecting D. edulis cultivars based on the intraspecific variation found in local populations in Cameroon and Nigeria, (ii) the identification of multi-trait ideotypes for potential cultivar development, (iii) the organoleptic attributes which are important traits for selection, and (iv) an assessment of the relationships between fruit mass and market prices in fruit samples from three markets, at the peak of season, in Cameroon

Rebuilding Tree Cover in Deforested Cocoa Landscapes in Côte d’Ivoire: Factors Affecting the Choice of Species Planted

Intensive cocoa production in Côte d’Ivoire, the world’s leading cocoa producer, has grown at the expense of forest cover. To reverse this trend, the country has adopted a “zero deforestation” agricultural policy and committed to rehabilitating its forest cover through the planting of high-value tree species in cocoa landscapes using a participatory approach. However, little is known regarding the factors influencing farmers’ introduction of high-value tree species to cocoa landscapes. We tested the hypothesis that ten previously reported factors to influence agroforestry system adoption to predict the number and choice of tree species that farmers introduce to cocoa farms. We interviewed 683 households in the cocoa-producing zone of Côte d’Ivoire and counted tree species on their cocoa farms. On average, two tree species were recorded per surveyed farm. Generalized Poisson regression models revealed that, in the cocoa production area, experience in tree planting and expected benefits, including income and food, influence tree species introduction through planting or “retention” when clearing land for cocoa establishment. The age of the farmer also influenced (p = 0.017) farmers’ tree species planting on cocoa farms. Fewer tree species were introduced into current intensive cocoa-production areas than in “old cocoa-loops” and forested areas. The number of tree species introduced to cocoa farms increased with expected benefits and experience in tree planting. The number of planted tree species also increased with farmers’ age. Tree species were mostly selected for the provision of shade to cocoa, production of useful tree products (38%), and income from the sale of these products (7%). Fruit tree species were the most planted, while timber tree species were mostly spared when clearing land for cocoa production

Domestication of Irvingia gabonensis: 2. The selection of multiple traits for potential cultivars from Cameroon and Nigeria

Ten fruit and kernel traits were assessed in 24 fruits of each of 152Irvingia gabonensis trees in three distinct populations inwest and central Africa [2 populations of non-planted trees in Cameroon:Nko'ovos II (21 trees) and Elig-Nkouma (31 trees) and 1 population ofplanted trees in Nigeria: Ugwuaji (100 trees)]. Strong relationships were foundbetween fruit weight and other fruit traits (e.g. flesh weight[r 2 = 0.99: P < 0.001],fruit length [r 2 = 0.74–0.83:P < 0.001], fruit width[r 2 = 0.77–0.88: P< 0.001]). In contrast, relationships between kernel weight and otherkernel/nut traits (e.g. shell weight and nut weight) were found to be weak[r 2 = 0.009–0.37, P =0.058–0.001], with the exception of nut weight at Nko'ovos II(r 2 = 0.65, P < 0.001).Relations hips between fruit and kernel traits (fruit massv. kernel mass, fruit mass v. shellmass, flesh mass v. kernel mass, nut massv. fruit mass and flesh depth v.kernel mass) were found to be very weak. This indicates that domesticationthrough the selection and vegetative propagation of multiple-trait superiorphenotypes is unlikely to be able to combine good fruit characteristics and goodkernel characteristics within cultivars. Consequently, domestication activitiesshould independently focus on ideotypes representing: lsquofresh fruitrsquotraits, and lsquokernelrsquo traits, that combine high values of thedifferent fruit and kernel characteristics respectively. Evidence from thisstudy indicates that selection of the three trees closest to the fruit ideotypeper village as the mother plants for vegetative propagation and cultivardevelopment, should give village level gains of 1.3 – 2-fold in fruitmass, and up to 1.5-fold in taste. Similarly for the kernel ideotype, selectionof the three trees with the best fit would give potential gains in kernel massof 1.4 – 1.6-fold

Domestication of Irvingia gabonensis: 4. tree-to-tree variation in food-thickening properties and in fat and protein contents of dika nut

Dika nut kernels were extracted from the nuts of 24 Irvingia gabonensis fruits collected from 151 trees in three villages in Cameroon and Nigeria. Methods were developed for the milling, de-fatting, hot-water pasting and rapid visco-analysis of the samples, to simulate the cooking of dika nut meal as a food-thickening agent. Two parameters (viscosity and drawability), thought to relate to the soup-thickening quality of dika nut meal, were derived from the traces. The samples exhibited significant tree-to-tree variation in viscosity, drawability and fat content, and differences between their villages of origin were significant. Thickening was found not to be directly associated with protein content. Similarly, the fat content did not contribute to the thickening properties at temperatures above fat melting point. Fat determination and fatty acid profiling indicated that the fat content ranged from 37.5% to 75.5% and identified myristic and lauric acids as the major fatty acid components. This study is part of a wider tree domestication project characterising tree-to-tree variation in fruit, nut and kernel traits of I. gabonensis with the aim of improving the livelihoods of subsistence farmers

Domestication potential of Marula (Sclerocarya birrea subsp. caffra) in South Africa and Namibia: 2. Phenotypic variation in nut and kernel traits

As part of a wider study characterizing tree-to-tree variation in fruit traits as a pre-requisite for cultivar development, fruits were collected from each of 63 marula (Sclerocarya birrea) trees in Bushbuckridge, South Africa\ud and from 55 trees from the North Central Region of Namibia. The nuts were removed from the fruit flesh, and the kernels extracted, counted and weighed individually to determine the patterns of dry matter partitioning among the nut components (shell and kernel) of different trees. Mean nut, shell and kernel mass were not significantly different between the two countries. Between sites in South Africa there were highly significant differences in mean nut mass, shell mass, kernel mass and kernel number. In Namibia, there were highly significant differences between geographic areas in mean shell mass, kernel mass and kernel number, but not in nut mass. These differences had considerable impacts on shell:kernel ratios (8.0-15.4). In South Africa, mean kernel mass was significantly greater in fruits from farmers’ fields (0.42 g) than from communal land (0.30 g) or natural woodland (0.32 g). Within all sites, in both South Africa and Namibia, there was highly significant and continuous variation between individual trees in nut mass (South Africa=2.3-7.1 g; Namibia=2.7-6.4 g) and kernel mass (South Africa=0.09-0.55 g; Namibia=0.01-0.92 g). The small and valuable kernels constitute a small part of the nut (Namibia=6.1-11.1%; South Africa=7.6-10.7%). There can be 4 kernels per nut, but even within the fruits of the same tree, kernel number can vary between 0-4, suggesting variation in pollination success, in addition to genetic variation. The nuts and kernels of the Namibian trees were compared with the fruits from one superior tree ('Namibian Wonder': nuts=10.9 g; kernels=1.1 g). Oil content (%) and oil yield (g/fruit) also differed significantly between trees (44.7-72.3% and 8.0-53.0 g/fruit). The percentage frequency distribution of kernel mass was skewed from trees in farmers’ fields in South Africa and in some sites in Namibia, suggesting a level of anthropogenic selection. It is concluded that there is great potential for the development of cultivars for kernel traits, but there is also a need to determine how to increase the proportion of nuts with four kernels, perhaps through improved pollination success