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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.
41

An investigation into the challenges facing Thulamela Local Municipality with regard to the supply of electricity

Magoro, Salminah Azwinndini 11 December 2012 (has links)
Oliver Tambo Institute of Governance and Policy Studies. / MPM
42

Institutional capacity of electricity supply services for rural communities in Mutale Local Municipality of Limpopo Province

Mudzanani, Nkhangweleni Seth 12 February 2016 (has links)
MPM / Oliver Tambo Institute of Governance and Policy Studies
43

Impacts of greenhouse gases from coal power stations on climatic trends in Witbank areas, South Africa

Mafamadi, Mercia Aluwani 18 May 2018 (has links)
MESHWR / Department of Hydrology and Water Resources / Greenhouse gases (GHGs) from coal power station affect the behaviour of climatic parameters such as the temperature, rainfall and evaporation, over a long period of time, hence causing climatic trends. This study focused on investigating the impacts of Greenhouse gases (GHGs) from coal power stations on climatic and hydrological trends in Witbank area. To accomplish this, linear regression (LR) and Mann-Kendall (MK) trend test were used to detect the hydro-climatic trends and their significance. GHG emissions were obtained from Eskom’s sustainability report on the Eskom website. Temperature data for the years 1950- 2000 and 1993-2016 and rainfall data for the years 1925-2000 and 1993-2016 were used. Double Mass Analysis (DMA) was used to check the homogeneity and consistency of temperature and rainfall data from South African Weather Services (SAWS) station with the Lynch database and Water Research Commission (WRC) data. Data was patched and extended using LR where necessary. Trends in temperature, precipitation and flow were assessed using MK trend test and LR based on monthly, seasonal, and annual scales. GHG emissions were compared with the hydro-climatic data over time in order to detect the impacts of GHG emissions on temperature, rainfall and streamflow. The MK results indicated that GHG emissions had some impacts on temperature with statistically significant increase in annual, monthly and seasonal time scales for the period 1950-2016. LR also produced the same results for annual temperature. Monthly and seasonal temperature could not be produced with the LR method because of data gaps. The MK and LR models produced similar results, indicating that there was a non-significant increase in temperature before coal power stations were introduced (1950-1974) and a significant increase in temperature after the commissioning of coal power stations (1975-2016). MK and LR also produced the same results for annual rainfall data, indicating that there was a significant increase in rainfall before coal power stations were introduced (1925-1974) and a non-significant increase after the commissioning of coal power stations (1975-2016). For monthly time scales MK and LR indicated increasing and decreasing trends before and after coal power stations were introduced. MK and LR results for streamflow stations B2H004 and B2H007 showed similar results indicating non-significant increase in annual and seasonal streamflow, but differed in monthly streamflow where MK showed significant increases whilst LR showed non-significant trends. The study concluded that GHGs from coal power stations had significant impacts on the hydro-climatic trends in Witbank area. GHGs from coal power stations caused significant increase in temperature as temperature increased by 3.7°C after coal power stations were introduced, whereas temperature had increased by 1.7 °C. It is recommened that more research should be done on alternative sources of energy such as wind and solar energy to check their suitability and applicability in South Africa. / NRF
44

Membrane bioreactor application within the South African textile industry: pilot to full-scale

De Jager, Debbie January 2013 (has links)
Thesis submitted in the requirements for the degree Doctor Technologiae: Chemical Engineering in the Faculty of Engineering at the CAPE PENINSULA UNIVERSITY OF TECHNOLOGY, 2013 / To date, limited information has been published on textile wastewater treatment, for re-use, in South Africa (SA), with treatment processes focusing on conventional wastewater treatment methods. A large contributor to the contamination of water within textile industries is from dyehouse processes. A major concern in textile wastewater treatment is the release of azo dyes and their metabolites, some of which are carcinogenic and mutanogenic, into the environment since they are xenobiotic and aerobically recalcitrant to biodegradation. A necessity therefore exists to find an effective treatment method capable of removing both the strong colour and the toxic organic compounds from textile wastewater. Membrane bioreactors (MBRs) are favoured when treating high-strength wastewater, since the membrane area is determined by the hydraulic throughput and not the biological load; no sludge is wasted and all bacteria are retained within the reactor, including specific bacteria capable of degrading the toxic, non-biodegradable constituents present in textile wastewater. MBR systems, using various configurations have been utilised extensively in the rest of the world to treat textile wastewater at both lab and pilot-scale. This DTech project formed part of a collaborative Water Research Commission (WRC) funded project K5/1900 - Pilot application of a dual-stage membrane bioreactor (dsMBR) for industrial wastewater treatment. The main purpose of this study was the on-site evaluation of a pilot-scale dsMBR incorporating two ultrafiltration (UF) sidestream membrane modules for the treatment, recovery and re-use of textile wastewater. The objectives of this project were to determine the treatment efficiency of the system; to evaluate the degree of colour removal from the textile wastewater; to improve residual colour removal within the system using treatment processes, such as NF and RO, as well as to propose a design and cost for a full-scale plant. A textile industry located in Bellville, Western Cape, was chosen as the industrial partner for the on-site evaluation of a semi-automated pilot wastewater treatment MBR plant using two 5.1 m2 Norit X-flow AirliftTM membrane modules. Since the wastewater treatment system was located on the premises, real continuously changing industrial wastewater was being treated. The industrial textile wastewater was treated in a series of tanks: 1) an anaerobic tank, which cleaved the azo bonds of the reactive dyes; 2) an anoxic tank containing reduced amounts of dissolved oxygen, in which denitrification occurred; and 3) an aerobic tank, in which i) nitrification, as well as ii) mineralisation of the aromatic amines occurred. The UF-membrane modules would account for the removal of any organic material. The wastewater stream was characterised by a chemical oxygen demand (COD) range of between 45 to 2,820 mg/L and an average biological oxygen demand (BOD) of 192.5 mg/L. The dsMBR achieved an average COD reduction of 75% with a maximum of 97% over the 220 day test period. The COD concentration obtained after dsMBR treatment averaged at 191 mg/L, which was well within the City of Cape Town industrial wastewater discharge standard. The average reduction in turbidity and TSS was 94% and 19.6%, respectively, during the UF-MBR stage of the system. Subsequent treatment of the UF permeate with nanofiltration (NF) for 4 days, alternated with reverse osmosis (RO) for 14 days removed both the residual colour and salt present in the UF permeate. A consistent reduction in the colour of the incoming wastewater was evident. The colour in the wastewater was reduced from an average of 659 ADMI units to ~12 ADMI units in the NF permeate, a lower American dye manufacturing index (ADMI) (i.e. method of colour representation) compared to the potable water (~17 ADMI units) utilised by the industrial partner in their dyeing processes. The colour was reduced from an average of 659 to ~20 ADMI units in the RO permeate, a lower ADMI and therefore colour when compared to the potable water. An average conductivity rejection of 91% was achieved with conductivity being reduced from an average of 7,700 to 693 μS/cm and the TDS reduced from an average of 5,700 to 473 mg/L, which facilitated an average TDS rejection of 92%. Based on the composition of the UF permeate fed to the RO membrane a maximum removal of 98.7% was achieved for both conductivity and total dissolved solids (TDS). The proposed full-scale plant would incorporate a UF-MBR system, followed by NF, RO, flocculation and a filter press. Therefore, the two waste products produced during operation of the proposed full-scale plant, would be the solid filter cakes and the liquid filtrate from the filter press. Implementing the proposed full-scale plant it would cost the industrial partner an operating cost of ZAR 113.85 and ZAR 3,415.49 to treat 97.1 m3 and 2,913 m3 of textile wastewater, respectively, per day and per month. This results in an annual saving of ZAR 845,848 on potable water expenses. This research, would provide SA textile industries, with an option to: 1) reduce their water consumption, thereby utilising less of a valuable decreasing commodity; 2) meet the SA government discharge standards and reduce their discharge costs; 3) reduce their carbon footprint (i.e. reduce their impact on the environment) by re-using their treated wastewater and therefore using less water from the municipality; and 4) decrease their annual expenditure on water, since the treated wastewater would be available for re-use.
45

Women in engineering : identifying and analyzing gender socialization in the faculty of engineering at the University of Kwazulu-Natal

Francis, Maryann Marilyn 11 1900 (has links)
The research problem reflected a lower number of female postgraduate students and academics as compared to their male counterparts within the Faculty of Engineering at the University of KwaZulu-Natal. A descriptive survey was disseminated to a stratified sample of undergraduate final year students in the disciplines of Chemical, Civil, Mechanical, Electrical, Electronic, Computer and Bioresources Engineering. An online survey was also sent to the nine female academics within the Faculty. The study indicates that the social and academic environment within the Faculty of Engineering at the University of KwaZulu-Natal was not a deterrent to female graduates studying further and entering academia. The exam performance of both male and female students was similar and neither the drop-out rate nor failure was due to gender but rather to the choice of degree. An issue of concern to both the student and the academic group was the low numbers of female academics. / Development Studies / M.A. (Development Studies)
46

Program management practices in context of Scrum : a case study of two South African software development SMMEs

Singh, Alveen January 2015 (has links)
Submitted in fulfilment of the requirements for the degree of Doctor of Technology: Information Technology, Durban University of Technology, Durban, 2015. / Agile approaches have proliferated within the software development arena over the past decade. Derived mainly from Lean manufacturing principles, agile planning and control mechanisms appear minimal and fluid when compared to more traditional software engineering approaches. Scrum ranks among the more popular permutations of agile. Contemporary literature represents a rich source of contributions for agile in areas such as practice guidelines, experience reports, and methodology tailoring; but the vast majority of these publications focus on the individual project level only, leaving much uncertainty and persistent questions in the multi-project space. Questions have recently been raised, by both academics and practitioners alike, concerning the ability of Scrum to scale from the individual project level to the multi-project space. Program management is an area encompassing practice and research areas concerned mainly with harmonizing the existence of competing simultaneous projects. Existing literature on program management essentially perceives projects as endeavours that can be carefully planned at the outset, and controlled in accordance with strong emphasis placed on economic and schedule considerations. This complexion seems to be mostly a result of well-established and ingrained management frameworks like Project Management Institute (PMI), and is largely at odds with emerging practices like Scrum. This disparity represents a gap in the literature and supports the need for deeper exploration. The conduit for this exploration was found in two South African software development small to medium sized enterprises (SMMEs) practicing Scrum. The practical realities and constraints faced by these SMMEs elicited the need for more dynamic program management practices in support of their quest to maximize usage of limited resources. This thesis examines these practices with the aim of providing new insights into the program management discourse in the context of Scrum software development environments. The research approach is qualitative and interpretive in nature. The in-depth exploratory case study research employed the two software SMMEs as units of analysis. Traditional ethnographic techniques were commissioned alongside minimal researcher participation in project activities. Activity Theory honed the data analysis effort and helped to unearth the interrelationships between SMME characteristics, program management practices, and Scrum software development. The results of the data analysis are further refined and fashioned into eleven knowledge areas that represent containers of program management practices. This is the product of thematic analysis of literature and data generated from fieldwork. Seeing as the observed practices were highly dynamic in nature, concept analysis provided a mechanism by which to depict them as snapshots in time. As a theoretical contribution, proposed frameworks were crafted to show how program management practices might be understood in the context of organizations striving towards agile implementation. Furthermore, representations of the mutually influential interfaces of SMME characteristics and Scrum techniques that initiate the observed fluid nature of program management practices, are brought to the fore.
47

Travel patterns and safety of school children in the eThekwini Municipality

Dhoda, Salma January 2009 (has links)
Submitted in fulfilment of the academic requirements for the degree of Magister Technologiae: Department of Civil Engineering and Surveying, Faculty of Engineering and the Built Environment, Durban University of Technology, 2009. / The annual incidence of pedestrian casualties on South African roads is approximately 34 000. This includes 4 000 deaths, 10 000 serious injuries and 20 000 minor injuries, costing the country an estimated R2,55 billion. A large number of injuries involve children and this is distressing but preventing this is a challenge. Statistics indicate that pedestrians are most at risk. School children have been identified as forming a considerable percentage of pedestrians. Consequently it is important to understand factors that influence children's travel patterns as an initial step toward reducing the accident rate. This study examines children's travel patterns at primary and secondary schools in the eThekwini area. In the absence of statistics regarding journeys to transport children to school, a questionnaire survey was designed to determine demographics, mode of travel to school, travel cost and duration, factors influencing choices of alternate modes of travel and problems experienced during school travel in terms of road safety. In addition, an on-site investigation was undertaken to assess the relevant engineering aspects including geometric design, traffic calming, signage and other traffic management aspects. This study focuses on scholar transport and discusses the findings of pilot and focal surveys. On analyzing the data, various problems were identified, namely: the road environment favours drivers over pedestrians, an absence of a formal travel plan, poor driver behaviour and an absence of dedicated school buses. A range of possible solutions is recommended. The recommendations focus on the Engineering, Enforcement and Evaluation aspects.
48

Developing a sustainability benchmarking system : a case study of the provincial government Western Cape’s immovable asset assessment pilot project

Meiring, Casper Johannes Knoetze 04 1900 (has links)
Thesis (MPhil)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Building structures have a major impact on the quality of the macro-climates of the world, in particular in terms of pollution and environmental costs associated with their creation, operation and maintenance. Emerging global trends to make buildings more efficient, effective and sustainable, led to the question can one establish how sustainable existing buildings are? Building rating tools like LEED, BREEAM and Green Star, can already be used to rate and certify buildings in terms of their environmental performance and sustainability, but seem to fall short of establishing true overall building performance sustainability. As an architect, the researcher was involved in a project to develop a process for the Provincial Government Western Cape to comply with the Government Immovable Asset Management Act, Act no.19 of 2007 (GIAMA). The problem statement of this study links to the objective to comply with GIAMA, which requires that all government buildings be assessed in terms of their sustainability. This led to a number of research questions being asked. The first of these questions are what can be learnt from currently available rating systems and would it be possible to track and monitor the sustainability performance of a building over time. This triggered a series of related questions: What role can benchmarking play in establishing and tracking a building’s sustainability over time? How can benchmarking help to identify which part of a building’s overall sustainability is most in need of resourcing, to bring it closer to overall sustainability? How can capital and maintenance expense budgets associated with the building life-cycle be effectively utilised to bring buildings closer to overall sustainability? How can the availability of detailed information pertaining to the costs and benefits of green investments in existing buildings help building owners to identify the best initiatives to invest in? The methodology used in this study to answer the above questions is based on two research approaches. The first part made use of a literature review to establish and define the knowledge framework to be used in the second case study portion of the study. The methodology used for the case study was based on applied research, where the real life problems associated with the development of a suitability benchmarking process for the PGWC was documented and assessed. The results of the study found that there exist a missing link between theoretical knowledge of sustainability benchmarking and the legislative requirement of GIAMA and that this missing link is the standardised accurate and verifiable data required for the benchmarking process. In addition to this it was also found that the social aspects of buildings are generally neglected. A universal standard for collection of the required data is also needed. The study also highlighted that a general misperception exist that Environmental Sustainability is synonymous with the Sustainability paradigm. / AFRIKAANSE OPSOMMING: Bou strukture het 'n groot impak op die gehalte van die makro-streke van die wêreld. Veral in terme van besoedeling en die ekologiese koste wat verband hou met die ontwikkeling, werking en onderhoud daarvan. Globale opkomende tendense om geboue meer doeltreffend en volhoubaar te maak, het gelei tot die vraag: Hoe kan 'n mens die volhoubaarheid van 'n bestaande gebou vasstel? 'n Aantal bou-graderings-stelsels, soos LEED, BREEAM en Green Star, kan reeds gebruik word om geboue te gradeer en sertifiseer in terme van hul omgewingsvolhoubaarheid, maar skiet te kort ten opsigte van algehele volhoubaarheid van ʼn gebou. As ʼn argitek was die navorser betrokke by ʼn projek om ʼn proses te ontwikkel vir die Provinsiale Regering van die Wes-Kaap (PGWK) om te voldoen aan die Wet op die Bestuur van Onroerende Regeringsbates, Wet no. 19 van 2007. Die probleemstelling van hierdie studie koppel aan die vereiste om te voldoen aan Wet 19 van 2007, wat vereis dat alle regeringsgeboue geassesseer word ingevolge hul volboubaarheid . Dit het gelei tot 'n aantal navorsingsvrae: Eerstens, watter lesse kan geleer word uit die bestaande bou-graderings-stelsels en tweedens, is dit moontlik om op die volhoubaarheid van 'n gebou te monitor en gradeer oor tyd? Dit het tot verwante vrae gelei, naamlik: Watter rol die stel van maatstawe kan speel om die volhoubaarheid van ʼn gebou te monitor? Hoe kan die stel van maatstawe bepaal watter aspekte van 'n gebou die meeste hulpbronne benodig, ten einde dit nader aan algehele volhoubaarheid te bring? Kan die kapitaal- en instandhoudingsbegrotings, wat verband hou met die lewens-siklus van die gebou, effektief gebruik word om ʼn gebou nader aan volhoubaarheid te bring? Hoe kan die beskikbaarheid van inligting met betrekking tot die koste en voordele van groen beleggings van bestaande geboue, gebou-eienaars help om die beste inisiatiewe te identifiseer om in te belê? Die metode wat in hierdie studie gebruik is om bogenoemde vrae te antwoord, is gebaseer op twee navorsings benaderings. Die eerste deel van hierdie studie het gebruik gemaak van 'n literatuuroorsig om ʼn kennisraamwerk te definieer en te vestig, wat dan in die tweede deel van die studie, ʼn gevallestudie, gebruik word. Die metode wat gebruik is vir die gevalle studie is gebaseer op toegepaste navorsing, waar die werklike probleme wat verband hou met die ontwikkeling van 'n geskikte volhoubaarheid maatstawings proses vir die PRWK gedokumenteer en geassesseer is. Die resultate van die studie was die bevinding dat daar 'n vermiste skakel bestaan tussen die teoretiese kennis ten opsigte van ‘n maatstawings stelsel vir volhoubaarheid en die wetlike vereiste van Wet 19 van 2007. Die vermiste skakel is dat gestandariseerde, accurate en verifieerbare data bemodig word vir die maatstawings proses. Daar is ook gevind dat die sosiale impakte van geboue verwaarloos word. Die studie stel voor dat ʼn universele standaard benodig word vir die versameling van die vereiste data. Die studie het ook n belangrike observasie gemaak dat daar 'n algemene wanopvatting in die industrie bestaan dat Omgewingsvolhoubaarheid sinoniem is met die Volhoubaarheid paradigma.
49

Travel patterns and safety of school children in the eThekwini Municipality

Dhoda, Salma January 2009 (has links)
Submitted in fulfilment of the academic requirements for the degree of Magister Technologiae: Department of Civil Engineering and Surveying, Faculty of Engineering and the Built Environment, Durban University of Technology, 2009. / The annual incidence of pedestrian casualties on South African roads is approximately 34 000. This includes 4 000 deaths, 10 000 serious injuries and 20 000 minor injuries, costing the country an estimated R2,55 billion. A large number of injuries involve children and this is distressing but preventing this is a challenge. Statistics indicate that pedestrians are most at risk. School children have been identified as forming a considerable percentage of pedestrians. Consequently it is important to understand factors that influence children's travel patterns as an initial step toward reducing the accident rate. This study examines children's travel patterns at primary and secondary schools in the eThekwini area. In the absence of statistics regarding journeys to transport children to school, a questionnaire survey was designed to determine demographics, mode of travel to school, travel cost and duration, factors influencing choices of alternate modes of travel and problems experienced during school travel in terms of road safety. In addition, an on-site investigation was undertaken to assess the relevant engineering aspects including geometric design, traffic calming, signage and other traffic management aspects. This study focuses on scholar transport and discusses the findings of pilot and focal surveys. On analyzing the data, various problems were identified, namely: the road environment favours drivers over pedestrians, an absence of a formal travel plan, poor driver behaviour and an absence of dedicated school buses. A range of possible solutions is recommended. The recommendations focus on the Engineering, Enforcement and Evaluation aspects.
50

The development of transgenic sweet potato (Ipomoea batatas L.) with broad virus resistance in South Africa.

Sivparsad, Benice. 20 November 2013 (has links)
Sweet potato (Ipomoea batatas Lam.) is ranked as the seventh most important food crop in the world and its large biomass and nutrient production give it a unique role in famine relief. However, multiple virus infection is the main disease limiting factor in sweet potato production worldwide. The main objective of this research project was to develop a transgenic sweet potato cultivar with broad virus resistance in South Africa (SA). A review of current literature assembled background information pertaining to the origin, distribution and importance of the sweet potato crop; viruses and complexes infecting sweet potato; and the strategies used in sweet potato virus detection and control. A survey to determine the occurrence and distribution of viruses infecting sweet potato (Ipomoea batatas Lam.) was conducted in major sweet potato-growing areas in KwaZulu-Natal (KZN). A total of 84 symptomatic vine samples were collected and graft inoculated onto universal indicator plants, Ipomoea setosa Ker. and Ipomoea nil Lam. Six weeks post inoculation, typical sweet potato virus-like symptoms of chlorotic flecking, severe leaf deformation, stunting, chlorotic mosaic, and distinct interveinal chlorotic patterns were observed on indicator plants. Under the transmission electron microscope (TEM), negatively stained preparations of crude leaf sap and ultra-thin sections from symptomatic grafted I.setosa plants revealed the presence of elongated flexuous particles and pinwheel type inclusions bodies‟ that are characteristic to the cytopathology of Potyviruses. Symptomatic leaf samples from graft-inoculated I. setosa and I. nil were assayed for Sweet potato feathery mottle virus (SPFMV), Sweet potato mild mottle virus (SPMMV), Sweet potato chlorotic stunt virus (SPCSV), Sweet potato chlorotic fleck virus (SPCFV), Sweet potato virus G (SPVG), Sweet potato mild speckling virus (SPMSV), Sweet potato caulimo-like virus (SPCaLV), Sweet potato latent virus (SPLV), Cucumber mosaic virus (CMV), and Sweet potato C-6 virus (C-6) using the nitrocellulose membrane enzyme-linked immunosorbent assay (NCM-ELISA). The majority of leaf samples (52%) tested positive for virus disease and showed the occurrence of SPFMV, SPMMV, SPCSV, SPCFV, SPVG, SPMSV, and SPCaLV. Of these 7 viruses, the most frequently detected were SPFMV (39%), SPVG (30%), followed by SPCSV (13%) and SPMMV (12%). SPCaLV and SPCFV at 10% and SPMSV at 7% were found exclusively in samples collected from one area. SPFMV, SPVG, SPCSV, and SPMMV were identified as the most prevalent viruses infecting sweet potato in KZN. The genetic variability of the three major viruses infecting sweet potato (Ipomoea batatas Lam.) in KZN was determined in this study. A total of 16 virus isolates originating from three different locations (Umbumbulu, Umfume and Umphambanyomi River) in KZN were analyzed. These comprised of 10 isolates of Sweet potato feathery mottle virus (SPFMV), five isolates of Sweet potato virus G (SPVG) and one isolate of Sweet potato chlorotic stunt virus (SPCSV). The phylogenetic relationships of the SPFMV, SPVG and SPCSV isolates from KZN relative to isolates occurring in SA and different parts of the world were assessed. The division of SPFMV into four genetic groups (strains) according to the phylogenetic analysis of coat protein encoding sequences revealed mixed infections of the O (ordinary) and C (common) strains in sweet potato crops from KZN. All SPFMV isolates showed close lineage with isolates from South America, East Asia and Africa. The SPVG isolates showed high relatedness to each other and close lineage with other isolates, especially those from China and Egypt. Analysis of the partial sequence of the Heat shock protein 70 homologue (Hsp70h) gene indicated that the SPCSV isolate from KZN belongs to the West African (WA) strain group of SPCSV and showed close relatedness to an isolate from Argentina. The knowledge of specific viral diversity is essential in developing effective control measures against sweet potato viruses in KZN. Multiple virus infections of Sweet potato feathery mottle virus (SPFMV), Sweet potato chlorotic stunt virus (SPCSV), Sweet potato virus G (SPVG) and Sweet potato mild mottle virus (SPMMV) cause a devastating synergistic disease complex of sweet potato (Ipomoea batatas Lam.) in KZN. In order to address the problem of the multiplicity and synergism of sweet potato viruses in KZN, this study aimed to develop transgenic sweet potato cv. Blesbok with broad virus resistance. An efficient and reproducible plant regeneration protocol for sweet potato (Ipomoea batatas Lam.) cultivar Blesbok was also developed in this study. The effect of different hormone combinations and type of explants on shoot regeneration was evaluated in order to optimize the regeneration protocol. Coat protein (CP) gene segments of SPFMV, SPCSV, SPVG and SPMMV were fused to a silencer DNA, the middle half of the nucleocapsid (N) gene of Tomato spotted wilt virus (TSWV) and used as a chimeric transgene in a sense orientation to induce gene silencing in the transgenic sweet potato. Transformation of apical tips of sweet potato cv. Blesbok was achieved by using Agrobacterium tumefaciens strain LBA4404 harboring a modified binary vector pGA482G carrying the plant expressible neomycin phosphotransferase ll gene (nptll), the bacterial gentamycin-(3)-N-acetyl-transferase gene and the expression cassette. A total of 24 putative transgenic plants were produced from the transformed apical tips via de novo organogenesis and regeneration into plants under 50mg/L kanamycin and 200 mg/L carbenicillin selection. Polymerase chain reaction (PCR) and Southern blot analyses showed that six of the 24 putative transgenic plants were transgenic with two insertion loci and that all plants were derived from the same transgenic event. The six transgenic sweet potato plants were challenged by graft inoculation with SPFMV, SPCSV, SPVG and SPMMV- infected Ipomoea setosa Ker. Although virus presence was detected using NCM-ELISA, all transgenic plants displayed delayed and milder symptoms, of chlorosis and mottle of lower leaves when compared to the untransformed control plants. These results warrant further investigation under field conditions. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.

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