The Angolan population has to deal with a high child mortality rate and various deficiency syndromes due to malnutrition. The diet is mainly based on carbohydrate rich plants, lacking important macro- and micronutrients. Currently the majority of cultivated plants originate from regions outside Africa. Although indigenous edible plant species are incorporated in the African diet, they only play a minor role and are often neglected in agricultural systems. The introduction of nutritive, fast-growing American fruit species as ananas, avocado or guava displace natural growing crops. In recent years the potential of wild edible plants to combat malnutrition, face climate change and deal with existing soil conditions has become of special concern. Leavy vegetables as Amaranthus spec., legumes as cowpea (Vigna unguiculata (L.) Walp.) or fruits as marula (Sclerocarya birrea (A.Rich.) Hochst. or baobab (Adansonia digitata L.) have gained public and commercial interest. However, only a few African edible plant species are cultivated in small plantations (“Fazenda”) or home gardens in the surrounding of villages. Horticultural or nutritional data are often incomplete and not representative. The scientific knowledge even impairs for species which are not cultivated and regarded only as snack or child food by the local population. Such plants as from the genus of chocolate berries (Vitex L.), vine rubber (Landolphia P.Beauv.) or Parinari Aubl. were of special interest for this PhD thesis.
Iron and zinc are widely deficient in the diet of the Angolan population and plant products as fruits from Canarium schweinfurthii Engl. or leaves of Crassocephalum rubens (Juss. ex Jacq.) S.Moore can help to combat resulting syndromes. However, the obtained contents of the 43 plant species have to be verified on additional plant material as contents are known to vary. Nevertheless, the results serve as a baseline and represent first insights into the nutritive profile of the respective wild edible plants. Those important comparative values direct future research, although the inconsistency of plant individuals impede exact statements. On the other hand, this fact also bears a great research potential for studies on the effects of plant varieties, localities or age of tissues. Yields of the studied plant species and incorporated volumes of the edible plant parts are still unknown, but important parameters.
The forest tree Caloncoba welwitschii Oliv. has spiny fruits with a delicious, fatty orange pulp. Besides our studies no research focus was ever directed to its nutritional potential although the pulp is appreciated by the local population. A high number of seeds in respect to a comparatively low amount of pulp probably impede nutritional analysis and agricultural interest. However, an in-depth analysis of existing varieties and an appropriate selection could improve the yield as the pulp is of special nutritional value. It contains high amounts of calcium and magnesium, vitamin B1, B2 and E. The protein composition further revealed high amounts of indispensable amino acids (Thr, Val, Ile, Leu). The tree often remains in disturbed areas as it is usually protected against human placed fires. The rural population appreciate the ornamental flowers, its diverse medical applications and its ability to attract insects. This demonstrates the enormous potential wild edible plants can have protecting natural habitats and plant individuals. Useful species are safeguarded by locals and emphasizing the manifold utilizations and the nutritional potential of other species seem to be a promising opportunity protecting the natural environment. Benefits of indigenous food plants are therefore manifold. They already grow in surrounding areas and need no expensive cultivation techniques; they are likely more resistant to existing pests and cushion the effects of slash-and-burn farming on soil erosion and rising ground temperatures.
Barren, acidic soils with high plant-available amounts of metals as aluminum and manganese impede the cultivation of commercial introduced crops. Application of fertilizers or soil amelioration techniques to enhance the yield are time and cost intensive. Otherwise, indigenous edible plant species are adapted to local growing conditions and grow without special care. Thus, the analysis of physical and chemical soil characteristics was conducted for eight traditionally utilized edible plants from the province Uíge. As plants evolved together with their parameters, they developed different strategies to deal with high amounts of plant-available metals. One example are accumulators, plants which contain extraordinarily high metal contents in their aboveground tissue. Anisophyllea quangensis Engl. ex Henriq., Landolphia lanceolata (K.Schum.) Pichon, Tristemma mauritianum J.F.Gmel., and Eugenia malangensis (O.Hoffm.) Nied. are first described to contain more than 1000 ppm aluminum in their dried leaves and can thus be categorized as Al-hyperaccumulator. These plants survive on marginal sides and bear additionally edible fruits with nutritional potential and small amounts of Al. For this reason, they are of special interest combating malnutrition and can at the same time cover and protect the ground. Diversifying the agricultural system with local growing plants seem to be a promising alternative to current monocultures of conventional crops.
In course of the data evaluation, it became apparent that there is a huge lack of knowledge concerning wild edible plants in Africa. Comprehensive data about the nutritional profile, growing conditions, germination or yield only exist for model plants or common crops. Results of this PhD thesis therefore serve as first insight into the potential of a selection of wild edible plants from Angola. Exemplary a comprehensive literature review was conducted for the genus Landolphia P.Beauv. covering all research areas from rubber production over botanical investigations to mechanical studies. Striking are the close interactions of the different scientific disciplines. Ethnobotanical utilization patterns are closely linked to pharmacological studies or nutritional analysis. The subshrub Landolphia lanceolata, which is native to the D.R. Congo and Angola, was involved in all different analysis conducted in this thesis. Results and their complex interactions are briefly outlined. The rhizomatous species grows on fine sand in the savannah. The soil of the examined species from Uíge was extremely acidic and low in nutrients. However, high aluminum contents were found in the leaves indicating accumulation processes within the plant tissues. The aluminum content of the edible fruit pulp was further elevated, which, depending on quantity and frequency of consumption, can be a threat to human health. Other hazardous minerals were not found in the pulp. The delicious fruit contains further antioxidants, vitamin B1, C and E. Landolphia species can yield many fruits on one individuum, which are often sold on local markets and generate alternative income for the local population. Furthermore, leaves and roots of this species are known by traditional healers to relieve cough or rheumatism. Pharmacological studies already determined promising antiplasmodial activities of the root and leaf extract. The latex extraction from L. lanceolata roots is destructive and the obtained rubber of low quality. It is accordingly advisable to utilize other species of the genus Landolphia for rubber production.
As illustrated by the many purposes of Landolphia lanceolata, indigenous plant species can help to overcome some of the major problems African populations have to face. Wild edible fruits diversify the local diet and are an important source of macro- and micronutrients. The protection of existing populations and their habitat as well as intensified cultivation can help to recover disturbed, open vegetation sites. Erosion can be prevented and the soil will be safeguarded without external support as power or fund requirements. Further, the economic situation of the rural population would be improved by the sale of products from the species. Another advantage of indigenous plants in contrast to conventional crops are their multipurpose applications. A lasting agriculture with minimum management requirements can be developed, render unnecessary fertilizers, herbicides or insecticides. Investigations on wild edible plants therefore bear a great potential directing future research activities, inform the local population and implement sustainable utilization forms protecting the natural environment.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:87153 |
| Date | 20 September 2023 |
| Creators | Baumgärtel, Christin |
| Contributors | Lautenschläger, Thea, Neinhuis, Christoph, Papenbrock, Jutta, Technische Universität Dresden |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, doc-type:doctoralThesis, info:eu-repo/semantics/doctoralThesis, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
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