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University of Wales, Bangor (2010)

Balanites aegyptiaca : A resource for improving nutrition and income of dryland communities in Uganda

Okia, C. A

Titre : Balanites aegyptiaca : A resource for improving nutrition and income of dryland communities in Uganda

Auteur : Okia, C. A

Université de soutenance : University of Wales, Bangor

Grade : Doctor of Philosophy (PhD) 2010

Résumé
Balanites aegyptiaca (L.) Del. (desert date), an important but neglected indigenous fruit tree in the drylands of Uganda was studied with the aim of understanding its local use and management as a prerequisite for its domestication and commercialisation for improved livelihoods of dryland communities. The specific objectives were to : (i) document local knowledge on use, management and conservation, (ii) determine the distribution and population status, (iii) assess its phenology, fruit yield and characteristics, (iv) document local processing and market potential of the leaves, fruits and oil, and (v) determine the nutritional composition of leaves, fruit pulp and kernel. The study was conducted in the semi-arid areas of Katakwi and Adjumani districts in Uganda where Balanites is commonly found and utilised. The two districts are geographically and ethnically different thus, providing a basis for comparison. Information on local knowledge was collected through household survey using a semi-structured questionnaire, focus group discussions and key informant interviews. A total of 150 respondents comprising an equal number of males and females were interviewed. Four populations of Balanites were inventoried in the wild and on-farm using plotless sampling and nearest neighbour techniques. Phenological events (leafing, flowering and fruiting) were monitored monthly over two years. Key informant interviews were conducted to capture information on local processing of Balanites products while a rapid market survey involving 45 traders and 50 urban consumers was carried out to assess market potential of the products. Forty five local leaders were interviewed using a self-administered questionnaire about policy related issues on management and promotion of Balanites in Uganda. Nutritional composition of Balanites leaves, flowers, and fruit pulp, and the fatty acid profile of the oil extracted from seed kernels were determined using standard procedures. The results revealed that both communities from Katakwi and Adjumani districts are heavily dependent on Balanites products during the dry season and have accumulated local knowledge regarding its use and management. Although the Iteso community in Katakwi district consume Balanites fruits, they mainly prefer its leaves as a vegetable. In contrast, the Madi community in Adjumani district highly value its fruits for consumption and often use the nuts to extract edible oil. All these products were traded in local markets and contributed about 12% of household incomes. The market was, however, limited by the products‟ short shelf life, poor processing and lack of a developed market. Both communities used concoctions made from various parts of Balanites tree to treat ailments such as, skin infections, stomach-aches and joint pains. Ecologically, Balanites is mainly found along rivers and swamps in Karamoja, Teso and West Nile subregions and in sites dominated by moderately acidic sandy clay soil. The population density of Balanites was higher in Adjumani (17 – 30 trees ha-1) than in Katakwi (2 – 8 trees ha-1). There was no significant (P≤0.05) difference in tree densities in the wild and on-farm. There are no clear management arrangements for wild Balanites trees while those on-farms are managed by land owners. Balanites was rarely planted although 51% of the farmers claimed that they retained and managed natural regeneration on farms. Regeneration is insufficient due to annual bush fires. Leafing and flowering mainly occur in the dry season (November – March) while fruiting starts during dry season and extends into early rains (April - May). Fruits take seven to eight months to develop in the rainy season, and ripen in the dry season (December – February). The method used for leaf harvesting is destructive as it involves cutting small branches bearing young leaves. Fruits are mainly collected after abscission. In Katakwi district, the leaves are boiled and sold in markets while in Adjumani district the fruits are sold fresh. The local method used by women in Adjumani district to process Balanites oil is similar to that used for processing shea butter/oil. Despite the high oil demand, its production is low due to difficulties in cracking nuts ; hence only 5% of nuts are currently used for oil production. Nutritionally, Balanites leaves, flowers and fruit pulp are good sources of protein, K, Fe, Mn, Zn and Cu and in all cases, leaves and flowers were superior to fruit pulp. Kernel oil yield was 45% and the resulting oil contained four major fatty acids in the following order of magnitude : linoleic>oleic>stearic>palmitic. The level of unsaturated fats was higher (65.6%) than that of saturated fats (34.4%). There was no significant (P≤0.05) difference in fatty acid content of locally and solvent extracted oil. It is concluded that Balanites products are nutritionally and economically important for the rural dryland communalities in Uganda. There is a need to build upon the local knowledge documented in this study by developing techniques for cracking Balanites nuts to increase oil production. For the foreseeable future, work on Balanites should concentrate on value addition, product development, and sustainable management of wild and on-farm trees.

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