Biocontrol agents in combination with moringa oleifera leaf extract for integrated control of botrytis cinerea of tomato.

Masters Degree. University of KwaZulu-Natal, Pietermaritzburg.Tomatoes and tomato-based foods provide essential nutrients beneficial to human health. Despite these benefits from tomatoes, postharvest losses result in unprofitable tomato production in some parts of the world. During ripening and harvesting, tomato becomes susceptible to diseases resulting in shorter shelf life. Susceptibility of tomato plants to Botrytis cinerea which causes grey mould infection can occur at any growth stage and the most susceptible growth stage is during ripening and senescing. Factors such as mechanical injuries, inadequate storage conditions, inappropriate handling, and transport affect tomato quality. The use of chemicals not only negatively affects farmers' yield by further enhancing pesticide resistance to crop pathogens but also influences other sectors of communities through contamination of drinking water sources which is an environmental hazard. There is a need to emphasise and encourage sustainable agricultural strategies such as biological control and plant extracts as alternative strategies which are eco-friendly and economically sustainable. Therefore, the main aim of this research was to examine the effect of biocontrol agents and Moringa oleifera leaf extract, individually and in combination, to control B. cinerea on tomatoes in vitro and in vivo. A total of 48 biocontrol agents were isolated from different parts of tomato leaves, citrus leaves, mushrooms and erect prickly pear. The isolates were screened against B. cinerea for the inhibitory effect and as potential control of the pathogen on potato dextrose agar (PDA) and tomato fruits. Serratia marcescens, Bacillus pumilus and Bacillus safensis inhibited B. cinerea by more than 50% in vitro. During in vivo screening, Serratia and Bacillus isolates inhibited grey mould incidence on ‘Jam’ tomatoes by more than 70%. The scanning electron microscopy images of the pathogen samples treated with biocontrol agents showed swollen and lysed mycelia. Moringa leaf extracts (MLE) were prepared into four concentrations MLE 1%, MLE 2%, MLE 3% and MLE 4%. The MLE concentrations were tested for their antifungal activity on the pathogen growth during in vitro studies. High concentrations were found to have some inhibitory effect on the mycelial growth of B. cinerea. There was no significant difference observed in the control, MLE 1% and MLE 2% since no mycelial inhibition was observed after 7 days at 25°C. For in vivo studies, all the concentrations had some inhibitory effect against grey mould on ‘Jam’ tomatoes. This was evidenced by lower disease incidence observed on the fruits treated with the moringa leaf extract compared to the control treatment. Scanning electron micrographs showed morphological changes in the hyphae on the samples treated with concentrations of MLE and there was also a breakage on the pathogen hyphae. Furthermore, this study evaluated the integrated control of B. cinerea using S. marcescens, B. safensis and B. pumilus integrated with MLE 2% and MLE 3% in vitro and in vivo. S. marcescens, B. safensis and B. pumilus integrated with MLE 2% and MLE 3% successfully suppressed mycelial growth of B. cinerea in vitro. Treating tomato fruits with S. marcescens, B. safensis and B. pumilus integrated with MLE 2% and MLE 3% reduced the disease incidence of grey mould compared to the control. The SEM images of the mycelial growth of B. cinerea showed shrinkage, and breakage of pathogen mycelia and the spores were damaged showing breakage and immature spores both in vitro and in vivo. Integrating moringa leaf extract, Serratia spp. and Bacillus spp. have the potential to be an alternative to synthetic fungicides to control postharvest pathogens

Synthesis and characterization of high-quality PbI2 nanopowders from depleted SLA accumulator anode and cathode.

High-quality lead iodide (PbI2) nanoparticles were synthesized from both anode and cathode of a discarded sealed lead-acid accumulator as starting materials. The structure, morphology, chemical composition and optical properties of washed PbI2 were investigated using X-ray diffraction, field emission scanning electron microscope, photoluminescence and energy-dispersive X-ray spectrometer. The XRD measurements indicated the presence of pure hexagonal PbI2 nanoparticles. Application of the Scherrer equation indicates crystal sizes between 13.703 and 14.320 nm. SEM indicated the presence of spherical particle agglomerations between 1.5 and 3.5 μ m in diameter. The measured band gap using two methods was consistent at 2.75 eV. EDS results suggest the absence of impurities in the synthesized nanoparticles. The overall results suggest that discarded sealed lead-acid accumulators can source pure hexagonal-phase lead iodide nanoparticles with potential applications in perovskite solar cells. The novelty aspect is that this approach has not been previously reported

The possible introduction of advance pricing agreements in South Africa income tax legislation

This treatise analyses the suitability of the Advance Pricing Agreements (APA) for the South African Transfer Pricing legislation. The transfer pricing legislation places emphasis on the arm's length principle. Determining an arm's length price is problematic and as a result some countries have resorted to APA's to establish an arm's length price up-front, and thus avoid reviews and subsequent audits. The treatise first focuses on the transfer pricing provisions and other relevant applicable sections of the Act from the South African point of view, and it then examines the current status quo, i.e. the review processes used by the South African Revenue Services (SARS) as detailed in the Organisation of Economic Co-operation and Developments (OECD) Guidelines and the SARS Practice Note. Since negotiated tax treaties form part of the South Africa law, the impact of these treaties are discussed in Chapter 4. The treatise discusses in detail an APA from the OECD's point of view. It examines the objectives of an APA; the benefit and the shortcomings of using an APA. It then examines the APA request processes from a Canadian perspective and the administration of the APA from an USA perspective. The treatise examines South African trading partners using APA in transfer pricing matters, with reference to the effects and the challenges such countries face. The treatise concludes by looking at the benefits provided by use of an APA by South African major trading partners. The effect and the use of such APA will have in South Africa is also discussed and how it should be modelled; the present status quo with regard to personnel at SARS; and the possible impact the introduction and implementation will have in South Africa

A summary of new findings on the biological effects of selenium in selected animal species: a critical review.

Selenium is an essential trace element important for many physiological processes, especially for the functions of immune and reproductive systems, metabolism of thyroid hormones, as well as antioxidant defense. Selenium deficiency is usually manifested by an increased incidence of retention of placenta, metritis, mastitis, aborts, lowering fertility and increased susceptibility to infections. In calves, lambs and kids, the selenium deficiency demonstrates by WMD (white muscle disease), in foals and donkey foals, it is associated with incidence of WMD and yellow fat disease, and in pigs it causes VESD (vitamin E/selenium deficiency) syndrome. The prevention of these health disorders can be achieved by an adequate selenium supplementation to the diet. The review summarizes the survey of knowledge on selenium, its biological significance in the organism, the impact of its deficiency in mammalian livestock (comparison of ruminants vs. non-ruminants, herbivore vs. omnivore) and possibilities of its peroral administration. The databases employed were as follows: Web of Science, PubMed, MEDLINE and Google Scholar

Dopants concentration on the properties of various host materials by sol-gel method: Critical review

Over the past years, the interest in doped phosphor materials has been extensively studied, due to their potential in applications such as light emitting diodes (LEDs), photonic circuits, sensors, and luminescent thin films. The most investigated phosphor materials by researchers include strontium aluminate, Zinc aluminate, magnesium aluminate, silica, and so forth. The incorporation of dopant ions in the host materials has shown a significant effect on the luminescence efficiency and the emission bands' position, which influences their kind of application. To achieve such luminescent materials, the sol-gel method has proved to be a competent method for the synthesis of doped phosphor materials due to its high purity, high homogeneity, and low-temperature processing. In this review, various sol-gel-prepared doped nanophosphor materials have been investigated. The effect of dopant concentration on the optical, morphological, and structural properties of nanophosphors were thoroughly discussed. Informative conclusions and up-to-date recommendations were drawn for future research and the possible establishment of new applications

Overview on Different types of Solar Cells: An Update

Solar energy is free from noise and environmental pollution. It could be used to replace non-renewable sources such as fossil fuels, which are in limited supply and have negative environmental impacts. The first generation of solar cells was made from crystalline silicon. They were relatively efficient, however very expensive because they require a lot of energy to purify the silicon. Nowadays, the production of solar cells has been improved since the first generation (thin-film solar cells, dye-sensitized solar cells, perovskite solar cells, and organic solar cells). In this work, the development of solar cells was discussed. The advantages, limitations, challenges, and future trends of these solar cells were also reported. Lastly, this article emphasized the various practices to promote solar energy and highlighted the power conversion efficiency of the fabricated devices

Overview on Different Types of Solar Cells: An Update

Solar energy is free from noise and environmental pollution. It could be used to replace non-renewable sources such as fossil fuels, which are in limited supply and have negative environmental impacts. The first generation of solar cells was made from crystalline silicon. They were relatively efficient, however very expensive because they require a lot of energy to purify the silicon. Nowadays, the production of solar cells has been improved since the first generation (thin-film solar cells, dye-sensitized solar cells, perovskite solar cells, and organic solar cells). In this work, the development of solar cells was discussed. The advantages, limitations, challenges, and future trends of these solar cells were also reported. Lastly, this article emphasized the various practices to promote solar energy and highlighted the power conversion efficiency of the fabricated devices

Developments on Perovskite Solar Cells (PSCs): A Critical Review

This review provides detailed information on perovskite solar cell device background and monitors stepwise scientific efforts applied to improve device performance with time. The work reviews previous studies and the latest developments in the perovskite crystal structure, electronic structure, device architecture, fabrication methods, and challenges. Advantages, such as easy bandgap tunability, low charge recombination rates, and low fabrication cost, are among the topics discussed. Some of the most important elements highlighted in this review are concerns regarding commercialization and prototyping. Perovskite solar cells are generally still lab-based devices suffering from drawbacks such as device intrinsic and extrinsic instabilities and rising environmental concerns due to the use of the toxic inorganic lead (Pb) element in the perovskite (ABX3) light-active material. Some interesting recommendations and possible future perspectives are well articulated

A Review of the Impact of Zinc Oxide Nanostructure Morphology on Perovskite Solar Cell Performance

Zinc oxide (ZnO) has been widely studied over the last decade for its remarkable properties in optoelectronic and photovoltaic devices because of its high electron mobility and excitonic properties. It has probably the broadest range of nanostructured forms that are also easy and cheap to synthesize using a wide variety of methods. The volume of recent work on ZnO nanostructures and their devices can potentially overshadow significant developments in the field. Therefore, there is a need for a concise description of the most recent advances in the field. In this review, we focus on the effect of ZnO nanostructure morphologies on the performance of ZnO-based solar cells sensitized using methylammonium lead iodide perovskite. We present an exhaustive discussion of the synthesis routes for different morphologies of the ZnO nanostructure, ways of controlling the morphology, and the impact of morphology on the photoconversion efficiency of a given perovskite solar cell (PSC). We find that although the ZnO nanostructures are empirically similar, one-dimensional structures appear to offer the most promise to increasing photoconversion efficiency (PCE) by their proclivity to align and form vertically stacked layers. This is thought to favor electron hopping, charge mobility, and conductivity by allowing multiple charge conduction pathways and increasing the effective junction cross-sectional area. The combined effect is a net increase in PCE due to the reduced surface reflection, and improved light absorption