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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Gladiolus scabridus - the road to conservation and commercialisation.

Campbell, Tracey Barbara. January 2005 (has links)
There is at present a growing concern and awareness of the endangered status of many indigenous South African plants in the wild, a number of which have potential for commercial production. One such example is Gladiolus scabridus, a vulnerable species endemic to the mountains of northern KwaZulu-Natal and southern Swaziland. It has considerable potential due to its floral characteristics. However, little is known about its horticultural requirements. Thus propagation and cultural practices were investigated with the aim of both conservation and commercialisation of the species. The ideal conditions for G. scabridus seed germination were determined. The presence or absence of light had no significant effect. Optimum germination was achieved at 20 QC of both winged and dewinged seeds. Higher temperatures appear to have a negative effect on germination and none of the winged seeds germinated at 30 QC. Under ideal conditions, fresh seed showed significantly higher vigour and viability than stored seed although the germination of stored seed was hampered by a higher internal fungal content. Successful tissue culture protocol was established for G. scabridus axillary bud and cormel halve explants. During the initial shoot initiation and proliferation stages (stage I and 11), the significantly higher shoot numbers occurred in the absence of growth regulators in both explant types. However, shoots with 1.0 mg 1 -1 6-benzyl-amino-purine (BAP) and 0.5 mg 1 -1 1-naphthalene-acetic-acid (NAA) were healthier in appearance. Higher levels of 5.0 mg 1 -1 NAA inhibited shoot production and encouraged root development in cormel halve explants. During stage 11, axillary bud explants showed root and cormlet development. More roots were initiated without growth regulators, whilst 5.0 mg 1 -1 NAA resulted in significantly better cormlet development. Shoot and cormlet growth of cormel halve explants during stage II was not significantly affected by the presence or absence of NAA and BAP. Significantly more roots were produced with 5.0 mg 1 -1 NAA. During stage III (rooting), the presence of activated charcoal (AC) was essential for the initiation and development of roots in vitro. Root and cormlet development in all explant types was significantly affected by the interaction between the previous treatments from stages I and 11 and the new treatments. During stage IV (hardening off) , most explants died down in the hardening off media leaving resting cormlets. There was a significant interaction between 1.0 mg 1 -1 NAA and 0.3 % AC from stage III, resulting in significantly more cormlets in both axillary bud and cormel halve explants. There was successful cormlet growth after cold storage which is advantageous in reducing the need for acclimatization. G. scabridus corms were successfully forced out of their normal flowering period. Temperatures of 10,5.5 and 2 QC showed successful corm initiation although the corms need to be stored for longer at warmer temperatures. It is suggested that a treatment of 2 QC for 6 weeks is the optimal condition for forcing G. scabridus corms. Although originating from a stressful environment, G. scabridus appears to show capacities for improved growth under controlled conditions. Fertilizer applications enhanced growth and reduced the time to flowering. Nitrogen (N) was found to be important for vegetative growth, flowering and daughter corm development, whereas potassium (K) influenced cormel production. Fertilizer with higher N and lower K is appropriate for the beginning and middle of the growing season and then adjusted to a lower N and higher K fertilizer to promote cormel formation. G. scabridus was found to produce prolific numbers of cormels which is an important source of plant material. Mineral leaf analysis showed that optimum levels for wild species are lower than those for hybrid gladioli with the optimum levels affected by physiological corm maturity and subsequent plant growth. Norms for postharvest handling of cut G. scabridus spikes have been developed. Spikes held in 2 % sucrose had a longer vase life and better floret opening and quality than those kept in distilled water, Prolong, Chrysal, 2 % sucrose and 2 % ethanol, 1 % sucrose, 4 % sucrose, 1 % sucrose and 0.5 % JIK, 2 % sucrose and 0.5 % JIK and 4 % sucrose and 0.5 % JIK, 2 % fructose and 2 % glucose. The use of commercially available solutions should be used with caution. Florets produced a climacteric-like CO2 peak, but levels of ethylene were unmeasurable. Cold storage and the use of polypropylene sleeves delays senescence. G. scabridus spikes secrete droplets of a sticky substance which was confirmed to be extra floral nectar through HPLC analysis. Market research revealed a positive response to the species from consumers and retailers alike with potential for cultivation as a cut flower and bedding plant. However, the cost will determine supply and demand. A field study conducted at Bivane Dam, northern KwaZulu-Natal, confirmed that G. scabridus colonies prevail in rocky, quartzite outcrops where they become wedged between the rocks. Plants were found at different stages of development with populations of not more than 108 plants per colony. Soil data of G. scabridus sites was compared to that of two sites nearby. It was found that G. scabridus soils are higher in phosphorus (P), zinc (Zn) and organic carbon. Leaf analysis confirmed that they have adapted their growth to low nutrient levels. The G. scabridus studies have clearly shown that the species can be successfully moved from a wild plant to a commercially viable one and in so doing its conservation status can also be improved. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.
82

An investigation of the indigenous ways of knowing about wild food plants (imifino): a case study

Cimi, Phumlani Viwe January 2009 (has links)
This study was conducted in Grahamstown in the Eastern Cape, South Africa. It is a qualitative case study located within the interpretive paradigm and was carried out over a period of a year. The theory implicit in the interpretive paradigm is of human beings as interpreters and constructors of a meaningful world. Thus, the focus of this study was on investigating the benefits of indigenous ways of knowing about wild food plants (imifino) in conjunction with hands-on activity-based lessons. This was done with the view to promote a conceptual understanding of nutrition and conservation in the Natural Sciences. The transformation of the school curriculum in South Africa called Curriculum 2005 (C2005) underpinned by the outcomes-based education (OBE) philosophy also triggered this study. The C2005 and OBE emphasise that learners’ prior everyday knowledge should be taken into account during the teaching and learning processes. The intention of the curriculum is to promote the idea of grounding knowledge in local contexts, while being sensitive to global imperatives. Although the acquisition of western knowledge has been and still is invaluable to all, on its own, it has been incapable of responding adequately to modern society in the face of massive and intensifying disparities, untrammeled exploitation of resources, and rapid depletion of the earth’s natural resources. Essentially, indigenous knowledge systems represent both a heritage and resource that should be protected, promoted, developed and, where appropriate, conserved. It is a resource that should serve the present and succeeding generations as many people’s cultural practices still rely on the use of wild plants. Within this context it should be borne in mind that the overexploitation of natural resources threatens not only biodiversity but also local traditional knowledge systems and ultimately cultural heritage; and research has a role to play in this regard. The research process in this study evolved into two main phases. The initial phase involved mobilising Grade 7 learners’ prior everyday knowledge on wild food plants (imifino). This led to the second phase of the research project, which was aimed at developing concepts through three hands-on activity-based lessons. I invited a community member to give a lesson on what imifino is and how to collect and prepare it, with the belief that the involvement of parents and community members in learners’ education can help bridge the gap between everyday life and school science. It is for these reasons that I believe that the constructive perspective can provide an appropriate methodological framework, conceptual structure and terminology for analysis of teaching and learning activities on the use of wild food plants in this study. The data generation techniques used in this study were questionnaires, observations and interviews (semi structured and focus group). A wide range of data generation techniques were employed to crystallise and validate the data generated using triangulation. The results from the analysed data revealed that consideration of indigenous ways of knowing in conjuction with hands-on practical activities enhanced interaction and learning among the learners. Also, linking of scientific knowledge to learners’ everyday lives was useful in fostering meaning-making and conceptual development.
83

Indigenous plants in the Limpopo province : potential for their commercial beverage production

Rampedi, Isaac Tebogo 12 1900 (has links)
South Africa has over 19 500 different indigenous plant species. Most of these are of ethnobotanical significance and are still used by local rural communities as medicine, food and for making beverages. The relatively little research that has been conducted on indigenous plant species has focused mainly on their medicinal potential. However, in view of the rapidly growing size of the global and local beverage industry and their constant search for new products, beverage-making indigenous plant species may have commercial development potential. To date, no detailed studies have been conducted on these plants, especially in the species-rich Limpopo province. The aim of this study was, therefore to evaluate the potential of indigenous plants for commercial beverage production. In order to achieve this, a survey was conducted in the Limpopo province to identify beverage-making plants and to document beverage preparation methods. Selected beverages were analysed and evaluated for their nutrient and sensory characteristics and a market product acceptability survey was conducted to identify those beverages with the greatest potential for development. Sixty three different beverage-plant species were identified in three study areas within the Limpopo province. These were used for the preparation of teas, fruit juices and alcoholic beverages. Plants that received further research attention were selected on the basis of their status as indigenous plants, frequency of use, nature of harvesting methods and availability. Some of the selected beverages were found to be rich in nutrients, especially with respect to vitamin C and mineral content. Furthermore, sensory analyses and market surveys indicated that four species, namely, Doyvalis caffra, Garcinia livingstonei, Grewia flavescens and Englerophytum magalismontanum have potential for further development for the beverage industry while Athrixia phylicoides has commercialisation potential as a herbal tea. However, further research is required to improve and refine preparation methods and to ensure compliance with quality standards. The availability of sufficient plant material for the industry must also be ensured. This research has indicated that South African indigenous plants have untapped market potential for the beverage industry which, if developed sustainably, could contribute to economic growth of the rural parts of South Africa. / Environmental Sciences / D. Ed. (Environmental Management)
84

Diversité, endémisme, géographie et conservation des Fabaceae de l'Afrique Centrale / Diversity, endemism, geography and conservation of Fabaceae of Central Africa

Ndayishimiye, Joel 21 October 2011 (has links)
La connaissance de la distribution spatiale des espèces et leurs déterminants constituent les principaux thèmes de la biogéographie et de l’écologie. Cette thèse a été réalisée sur les Fabaceae de l’Afrique Centrale :Burundi, République Démocratique du Congo et Rwanda. Composées de trois sous-familles (Caesalpinioideae, Faboideae et Mimosoideae), les Fabaceae sont présentes dans tous les biomes terrestres du monde. La présente étude a pour objectif d’évaluer et localiser la diversité spécifique, déterminer les zones de conservation des Fabaceae, identifier leur modèle de distribution spatiale et examiner l’impact potentiel de la déforestation sur les espèces indicatrices de cette famille. Les facteurs environnementaux déterminant la distribution des espèces endémiques de Fabaceae, les zones favorables à leur présence et l’évaluation de leur état de conservation ont également été analysés. L’étude a consisté à vérifier et à digitaliser tous les échantillons d’herbiers des Fabaceae conservés au Jardin Botanique National de Belgique et à l’Université Libre de Bruxelles. Les Systèmes d’Information Géographique ont été largement utilisés. Les analyses spatiales ont montré une distribution non uniforme de la diversité spécifique des Fabaceae. Les zones où la diversité spécifique coïncide avec celle des espèces endémiques ont été suggérées comme prioritaires pour la conservation. L’analyse de groupement appliquée sur le jeu de données des Mimosoideae a mis en évidence trois régions floristiques majeures. Ces trois régions correspondent aux régions phytogéographiques définies par White (1979, 1983). L’étude des Caesalpinioideae a confirmé l’existence d’espèces indicatrices de territoires phytogéographiques de Ndjele (1988). L’étude de cas réalisée au Katanga (R.D. Congo) a montré que la déforestation constitue une menace potentielle pour ces espèces, les plus vulnérables étant inféodées aux habitats forestiers. La distribution potentielle des espèces endémiques de Fabaceae (Caesalpinioideae) a montré une convergence entre les cartes de la distribution actuelle et celles issues de la distribution potentielle. Des sites où les espèces n’ont jamais été signalées ont été identifiés. La distribution potentielle a démontré le rôle des déterminants environnementaux dans la distribution des espèces endémiques. Cette étude a également prouvé que d’importantes proportions des zones de diversité des espèces endémiques ne sont pas couvertes par la conservation actuelle de l’Afrique Centrale. Cette thèse confirme que l’Afrique Centrale est une zone importante de conservation de la biodiversité. L’étude devrait être poursuivie en étendant la distribution potentielle aux Fabaceae non endémiques afin de définir leurs aires de distributions, critère indispensable pour évaluer le degré de vulnérabilité d’une espèce. La création de nouvelles aires protégées renforcerait le système actuel de conservation dans cette région./Knowledge of the spatial distribution of species and its determinants constitutes a principal theme in biogeography and ecology. This dissertation focused on the Fabaceae family of Central Africa: Burundi, the Democratic Republic of the Congo and Rwanda. Composed of three subfamilies (Caesalpinioideae, Faboideae and Mimosoideae), Fabaceae species are present in all terrestrial biomes of the world. The current study aimed to assess and locate Fabaceae species diversity, to determine potential conservation zones, to identify the spatial distribution pattern and to examine the potential impact of deforestation on some indicator species of this family. The environmental factors driving the distribution of endemic Fabaceae have been identified, as well as the potential areas of occurrence; their conservation status in the region has also been studied. The current study has verified and digitized all the herbarium samples kept at the National Botanical Garden of Belgium and the Université Libre de Bruxelles regarding the Fabaceae family. Geographic Information Systems have been used frequently. Spatial analysis showed an uneven distribution of Fabaceae species diversity. The zones where species richness depends on endemic species diversity are suggested to have priority for conservation. A cluster analysis applied to the dataset of Mimosoideae has highlighted three major floristic regions. These three regions correspond to existing phytogeographical regions defined by White (1979, 1983). A study on Caesalpinioideae species of Central Africa has confirmed the existence of indicator species of phytogeographic territories of Ndjele (1988). A case study conducted in Katanga (D.R Congo) showed that deforestation constitutes a potential threat for these species, the most vulnerable being those strictly confined to forest habitats. The potential distribution of endemic Fabaceae (Caesalpinioideae) showed a clear convergence between the current distribution maps and the potential distibutions. Sites where those species had not been reported before have been identified. The potential distribution enabled to identify the importance of the different environmental factors for each endemic species’ distribution. This study also showed that large regions characterized by important endemic species diversity are not covered by current zones of conservation in Central Africa. This dissertation confirms Central Africa as an important zone for biodiversity conservation. The current research should be completed by the potential distribution of non endemic Fabaceae species of Central Africa, an important criterion to evaluate their degree of vulnerability. Creation of new protected areas would reinforce the current status of conservation in the region. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished
85

Etude taxonomique et biogéographique des plantes endémiques d'Afrique centrale atlantique: le cas des Orchidaceae / Taxonomic and biogeographic study of plants endemic to the Atlantic Central Africa: the case of the Orchidaceae

Droissart, Vincent 16 January 2009 (has links)
L’Afrique centrale atlantique (ACA) englobe l’ensemble du domaine bas-guinéen, les îles du Golfe de Guinée et une partie de l’archipel afromontagnard. Plusieurs centres d’endémisme ont été identifiés en son sein et sont généralement considérés comme liés à la présence de refuges forestiers durant les périodes glaciaires. Cependant, l’origine de cet endémisme, sa localisation et les méthodes permettant d’identifier ces centres restent controversées. La localisation de ces zones d’endémisme et des plantes rares qu’elles abritent, est pourtant un prérequis indispensable pour la mise en place de politiques cohérentes de conservation et demeure une priorité pour les organisations privées, institutionnelles ou gouvernementales actives dans la gestion et le maintien durable de la biodiversité.<p><p>Cette étude phytogéographique porte sur la famille des Orchidaceae et est basée sur l’analyse de la distribution des taxons endémiques de l’ACA. Elle s’appuie sur un jeu de données original résultant d’un effort d’échantillonnage important au Cameroun et d’un travail d’identification et de localisation de spécimens dans les principaux herbaria européens abritant des collections d’ACA. Durant cette étude, (i) nous avons tout d’abord identifié ces taxons endémiques et documenté leur distribution au travers de plusieurs contributions taxonomiques et floristiques, (ii) nous nous sommes ensuite intéressé aux nouvelles méthodes permettant d’analyser ces données d’herbier de plantes rares et donc pauvrement documentées, testant aussi l’intérêt des Orchidaceae comme marqueurs chorologiques, et finalement, appliquant ces méthodes à notre jeu de données, (iii) nous avons délimité des centres d’endémisme et identifié les territoires phytogéographiques des Orchidaceae en ACA.<p><p>(i) Une révision taxonomique des genres Chamaeangis Schltr. et Stolzia Schltr. a été réalisée respectivement. Sept nouveaux taxons ont été décrits: Angraecum atlanticum Stévart & Droissart, Chamaeangis spiralis Stévart & Droissart, Chamaeangis lecomtei (Finet) Schltr. var. tenuicalcar Stévart & Droissart, Polystachya engogensis Stévart & Droissart, Polystachya reticulata Stévart & Droissart, Stolzia repens (Rolfe) Summerh var. cleistogama Stévart, Droissart & Simo et Stolzia grandiflora P.J.Cribb subsp. lejolyana Stévart, Droissart & Simo. Plusieurs notes taxonomiques, phytogéographiques et écologiques supplémentaires ont également été redigées. Au total, nous avons identifié 203 taxons d’Orchidaceae endémiques d’ACA parmi lesquels 193 sont pris en compte pour l’étude des patrons d’endémisme.<p><p>(ii) Au Cameroun, les patrons de distribution des Orchidaceae et des Rubiaceae endémiques d’ACA ont été étudiés conjointement. Des méthodes de rééchantillonnage des données (raréfaction) ont été appliquées pour calculer des indices de diversité et de similarité. Elles ont permis de corriger les biais liés à la variation de l’effort d’échantillonnage. Un gradient de continentalité a été observé, les parties côtières étant les plus riches en taxons endémiques d’ACA. Contrairement à la région du Mont Cameroun et aux massifs de Kupe/Bakossi qui ont connu une attention particulière des politiques et des scientifiques, la partie côtière du sud Cameroun, presque aussi riche, reste mal inventoriée pour plusieurs familles végétales.<p><p>Cette analyse à l’échelle du Cameroun a également permis de comparer les patrons d’endémisme des Orchidaceae et des Rubiaceae. Les différences observées seraient principalement dues à la présence d’Orchidaceae terrestres dans les végétations basses et les prairies montagnardes de la dorsale camerounaise alors que les Rubiaceae sont généralement peu représentées dans ces habitats. Au sein des habitats forestiers, la concordance entre les patrons d’endémisme des Orchidaceae et des Rubiaceae remet en question l’utilisation des capacités de dispersion des espèces comme critère pour choisir les familles permettant l’identification des refuges forestiers et semble ainsi confirmer la pertinence de l’utilisation des Orchidaceae comme marqueur chorologique.<p><p>La distribution potentielle a été utilisée pour étudier en détail l’écologie, la distribution et le statut de conservation de Diceratostele gabonensis Summerh. une Orchidaceae endémique de la région guinéo-congolaise uniquement connue d’un faible nombre d’échantillons. Cette méthodologie semble appropriée pour compléter nos connaissances sur la distribution des espèces rares et guider les futurs inventaires en Afrique tropicale.<p><p>(iii) En ACA, les Orchidaceae permettent d’identifier plusieurs centres d’endémisme qui coïncident généralement avec ceux identifiés précédemment pour d’autres familles végétales. Ces constats supportent aussi l’utilisation des Orchidaceae comme marqueur chorologique. La délimitation des aires d’endémisme des Orchidaceae a ainsi permis de proposer une nouvelle carte phytogéographique de l’ACA. Les éléments phytogéographiques propres à chacune des dix phytochories décrites ont été identifiés et leurs affinités floristiques discutées. Les résultats phytogéographiques obtenus (a) soutiennent l’existence d’une barrière phytogéographique matérialisée par la rivière Sanaga entre les deux principaux centres et aires d’endémisme de l’ACA, (b) étendent l’archipel afromontagnard situé principalement au Cameroun au plateau de Jos (Nigeria) et (c) montrent l’importance de la chaîne montagneuse morcelée Ngovayang-Mayombe pour la distribution de l’endémisme en ACA. Cette chaîne de montagne, qui s’étend le long des côtes de l’océan du sud Cameroun au Congo-Brazzaville et qui correspond à plusieurs refuges forestiers identifiés par de nombreux auteurs, est ici considérée comme une seule aire d’endémisme morcelée./<p>Atlantic central Africa (ACA) covers the Lower Guinean Domain, the four islands of the Gulf of Guinea and a part of the afromontane archipelago. Different centres of endemism have been identified into this area and are usually considered as related to glacial forest refuges. However, the origin of this endemism, the localization of the centres and the methods employed to identify these centres are subject to debate. Yet, the localization of these centres of endemism and the identification of the rare plants they harbor is an essential prerequisite to setting up rational conservation policies, and remains a priority for private, institutional and governmental organizations which are dealing with the sustainable management of biodiversity.<p><p>This phytogeographical study focuses on Orchidaceae and analyses the distribution of the taxa endemic to ACA. We use an original dataset resulting from an important sampling efforts and the identification of specimens coming from all the principal herbaria where collections from ACA are housed. During this study, (i) we first identified the taxa endemic to ACA and documented their distribution through several taxonomic and floristic contributions, (ii) we used and developed new methods allowing to correct for sampling bias associated with the use of rare and poorly documented taxa, testing at the same time the use of Orchidaceae as chorological markers, and finally, applying these methods to our dataset, (iii) we delimited the centres of endemism and identified the phytogeographical territories of Orchidaceae in ACA.<p><p>(i) A taxonomic revision of Chamaeangis Schltr. and Stolzia Schltr. respectively was carried out. Seven new taxa were described: Angraecum atlanticum Stévart & Droissart, Chamaeangis spiralis Stévart & Droissart, Chamaeangis lecomtei (Finet) Schltr. var. tenuicalcar Stévart & Droissart, Polystachya engogensis Stévart & Droissart, Polystachya reticulata Stévart & Droissart, Stolzia repens (Rolfe) Summerh var. cleistogama Stévart, Droissart & Simo and Stolzia grandiflora P.J.Cribb subsp. lejolyana Stévart, Droissart & Simo. Several additional taxonomic, phytogeographical and ecological notes were also published. We finally identified 203 Orchidaceae taxa endemic to ACA, among which 193 were used to study the patterns of endemism.<p><p>(ii) In Cameroon, the distribution patterns of both Orchidaceae and Rubiaceae endemic to ACA were studied. Subsampling methods (rarefaction) were applied to calculate diversity and similarity indices and to correct potential bias associated with heterogeneous sampling intensity. A gradient of continentality was confirmed in Cameroon, the coastal part being the richest in taxa endemic to ACA. The Cameroon Mountain and the Kupe/Bakossi mountain massifs have received a great consideration of politics and scientists. On the contrary, the Southern coastal part of Cameroon, though almost as rich as the Northern part, remains poorly known for several plant families.<p>This analysis also allowed us to compare patterns of endemism of Orchidaceae and Rubiaceae. The differences observed could be mainly due to the terrestrial habit of some Orchidaceae, which are only found in the grasslands of the highest part of the Cameroonian volcanic line where endemic Rubiaceae are rare. Within forest habitats, the concordance between the patterns of endemism of Orchidaceae and Rubiaceae question the widespread use of dispersal ability as a selection criterion for the families used to identify forest refuges. This also confirms the relevance of Orchidaceae as chorological marker.<p><p>Species distribution modelling was used of an in depth study of the ecology, the distribution and the conservation status of Diceratostele gabonensis Summerh. an Orchidaceae endemic to the Guineo-Congolian regional centre of endemism which is only known from very few collections. This method is proved to be appropriate to complete our knowledge on the distribution of rare plant species and to guide the future inventories in tropical Africa.<p><p>(iii) In ACA, an analysis of the distribution of endemic Orchidaceae confirmed the presence and location of several centres of endemism previously identified on the basis of other plant families. This result again supports the use of Orchidaceae as a chorological marker. The chorological study of the endemic Orchidaceae allowed us to propose a new phytogeographical map for ACA. Phytogeographical elements for each of the ten phytochoria described were identified and their floristic affinities were also discussed. Our results (a) support the existence of a phytogeographical barrier, materialized by the Sanaga River, between the two main centres and area of endemism of the ACA, (b) extend the limits of the afromontane archipelago to the Jos Plateau in Nigeria and (c) show the importance of the Ngovayang-Mayombe line to explain the distribution of endemism in ACA. This mountainous line, stretching along the ocean coast from Southern Cameroon to Congo-Brazzaville, corresponds to several forest refuges identified by many authors, and is here considered as an unique but discontinuous area of endemism.<p><p><p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished
86

Life history, population dynamics and conservation status of Oldenburgia grandis (Asteraceae), an endemic of the Eastern Cape of South Africa

Swart, Carin January 2008 (has links)
Oldenburgia grandis is a rare, long-lived woody paleoendemic of the Fynbos Biome of South Africa. Confined to quartzite outcrops, it has a small geographic range and narrow habitat specificity. O. grandis responds to its fire-prone environment by resprouting. Elasticity analysis of O. grandis reveals that growth and fecundity were traded off for persistence of adult, mature and sapling stages. Morphological adaptations such as a corky fire-resistant bark and the ability to resprout after fire are traits that O. grandis have evolved to persist in a frequently disturbed environment. Population growth rate for sites undisturbed by fire for a number of years (l = 1.01) and sites at various stages of recovery after fire (l = 1.00) were very similar. The highest variation in transition probabilities for all sites was seen in the persistence of the seedling stage and growth from seedling to sapling. Observed population structure and stable stage distribution determined by the matrix model show that sites recently undisturbed by fire had high abundances of the adult and sapling stages. A peak in sapling stages was seen for the stable stage distribution where similar peak in sapling numbers were seen for population structures of sites at various stages of recoveryafter fire. Favourable environmental conditions for the persistence of O. grandis populations include no fire with transition probabilities between the observed minimum and maximum and fire frequency at a 10 year interval where seedling protection from the fire is high and adult and mature mortalities during the fire are low. Stochastic environmental events that could put populations (particularly small populations) at an increased risk of extinction include high to moderate fire intensities where seedling protection from the fire is low and adult and mature mortalities are high as a result of the fire.
87

The nutritional knowledge and consumption of blackjack by hypertensive patients in Vhembe District, Limpopo Province, South Africa

Gavhi, Fhatuwani 20 September 2019 (has links)
MSCPNT / Department of Nutrition / Hypertension remains a major public health problem that needs different comprehensive health strategies to deal with it. Indigenous vegetables, Blackjack in particular, have been shown to possess anti-hypertensive properties that are attributed to bioactive chemical substances such as phytochemicals, fiber, antioxidants as well as micronutrients that include potassium, magnesium, calcium, vitamin C, zinc, iron and copper. The use of indigenous vegetables in combination with the conventional hypertension treatment may reduce hypertensive conditions; hence, the purpose of this study was to determine Blackjack nutritional knowledge and consumption by hypertensive patients. A cross-sectional study employing both quantitative and qualitative methods was conducted on 275 hypertensive participants at Mphambo and Mutale Health Centers, Vhembe District of Limpopo Province, South Africa. A questionnaire was used to collect data on participants’ Blackjack nutritional knowledge, Blackjack availability around their households as well as their Blackjack consumption patterns and nutritional status. The Blackjack nutritional knowledge data was triangulated with focus group discussions and participants’ nutritional status was assessed by anthropometric and dietary intake methods. The body mass index (BMI) was calculated and dietary intake frequency from selected foods was determined. Blood pressure was measured using Microlife automatic blood pressure monitor. The findings indicated that most hypertensive participants had poor knowledge of the nutritional importance of Blackjack and its associated medicinal contribution on hypertension management. Participants were unable to mention different diseases that can be prevented or managed by Blackjack, which was mostly consumed once a week with porridge during the summer season. Hypertensive patients were consuming high amounts of sodium and less amounts of minerals that are known to regulate blood pressure, such as potassium and magnesium. Hypertensive patients had high prevalence of overweight and obesity and most were either in hypertension stage 1 or stage 2. Lack of Blackjack nutritional knowledge may have contributed to a decreased consumption of Blackjack by hypertensive patients. The health professionals should promote the nutritional benefits of Blackjack in rural areas, particularly to hypertensive patients to raise awareness of Blackjack’s benefits in disease prevention and management. / NRF
88

Use of the Athrixia phylicoides plant in Tshwane: an anthropological study

Siko, Maggie Ngwanamaphoto 02 1900 (has links)
This study focuses on the use of the Athrixia phylicoides plant in Tshwane, Gauteng, South Africa. The plant is used within the domestic domain as a beverage, for medicinal purposes, as well as for the manufacturing of domestic brooms. The aim of the study was to investigate the use and market of Athrixia phylicoides in two of the Tshwane markets, namely; Denneboom and Marabastad. Case study design, participant observation and interviews were employed to collect data. A literature review was conducted to construct a theoretical framework. The study reveals that traditional healers, broom makers and customers have a remarkable knowledge about Athrixia phylicoides, which has been untapped thus far. In addition, the study indicates that possible extinction of the Athrixia phylicoides plant, due to over-harvesting and lack of conservation, will pose a challenge to the market. / Anthropology / M.A. (Anthropology)

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