A study on certain factors that may affect the economic viability of backgrounding beef weaner calves on pastures in the Southern Cape area of South Africa
- Authors: Terblanche, Ian
- Date: 2020
- Subjects: Calves -- Weaning -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/47623 , vital:40259
- Description: The backgrounding of beef weaner calves from pastures has the potential to be developed as an intensive beef enterprise that can increase the income of smaller farms, given that these farms have the ability to produce good quality pastures. This study was conducted to verify the inputs that impact on the viability of pasture backgrounding systems in an attempt to provide beef producers with better information for decision making. The scientific research was conducted with the registered Kromme Rhee Bonsmara herd at the Kromme Rhee research farm of the Western Cape Department of Agriculture. The farm is situated at 18º50’E and 33º51’S in the Stellenbosch area and has an altitude of 177 m above sea level. The area is situated in the winter rainfall region of the Western Cape with an annual rainfall of 670 mm. The average summer temperature ranges between 15-35 ºC and winter temperature between 10-17 ºC. The aim of this study was to develop growth curves representing the growth of Bonsmara animals for use by beef producers in predicting future live weight of animals in a pasture backgrounding system. Dry matter (DM) intake was measured at various live weight stages in order to determine whether a prediction model could be established to represent the DM intake of growing Bonsmara cattle on pastures. Results were used as inputs to determine whether backgrounding on pastures was economically viable. Animals were weighed at monthly intervals. Weighings commenced from birth and continued for a period of 797 days, repeated with two production year groups. One group consisted of 18 heifers and 12 bulls that were weighed from birth till an average age of 759 days. The other group consisted of four heifers and seven bulls and was weighed from birth untill an average age of 892 days. Roughage supplementation was done with lucerne hay in periods of pasture shortfalls, while a protein and energy lick were supplied continuously. A feeding trial with 10 weaned heifers and 10 bull calves of the same year group was conducted to determine the average feed intake per individual animal over a thirteen-month period that commenced after weaning. Two groups of five Bonsmara bull calves and two groups of five Bonsmara heifers were grouped according to age and gender. The feed intake of the growing calves was recorded for different live weight categories. The animals received lucerne (Medicago sativa) hay on an ad lib basis, while a concentrate supplement was supplied at 2 kg per animal per day up until live weights of 350 kg for heifers and 380 kg for bulls was achieved. The lucerne based diet was formulated to simulate a diet for growing animals on pasture with additional supplementation. Group feed intake values of the four groups of animals were measured at about 20-day intervals over the trial period of 369 days. The feed waste was dried and weighed back to calculate a waste percentage to be used as a correction factor. The Gompertz growth function was used to develop growth curves for male and female Bonsmara animals. Results indicated a significant difference between the mature weight of males and females (P <0.05). In both year groups the nonlinear Gompertz growth model predicted heavier mature weight for males compared to females. Mature weights of bulls were respectively 44.4% and 68.5% higher than that of heifers over the two year period. Days at maximum growth occurred later for males than for females (P <0.05) and the maturing rate of males and females did not differ significantly. Individual average feed intakes were calculated from the group fed animals over the duration of the rearing period. The data revealed that feed intake for bulls can be predicted by the linear model, DMI= 0.16531 + 0.0235306 x live weight (P ≤0.001; R 2 = 78.25). The feed intake of heifers can be predicted by the linear model, DMI= -1.41991 + 0.0283891 x live weight (P ≤0.001; R 2= 76.25). Analysis of variance detected no difference between the percentage feed intake of heifers (2.46%) and bulls (2.40%), over the experimental period. Prices of different live weight groupings were analysed over seven years to establish whether cyclical price trends can be observed across years and seasonal price trends within years. Within years prices were found to differ between months. For all calf weight groups, the lowest prices occurred in the months of March, April, May, June and July which showed price indices significantly different (P <0.05) from indices of the months of October, November and December when highest prices occurred, confirming seasonality in weaner calf prices. Price indices were developed for use as an input in the economic viability assessment. A brief literature review on the production and quality of four common pastures in the Southern Cape was done to gather information for compiling pasture budgets for use in determining the economic viability of pasture backgrounding. The economic viability of backgrounding on pastures was evaluated on a gross margin level and illustrated for three pasture systems namely irrigated oats as a winter pasture, irrigated lucerne as a spring pasture and dryland P. clandestinum /E. plana /mixed grass also as a low-cost spring pasture. All three pasture systems showed a positive economic viability for the decision parameters used in the illustration. The gross margin of backgrounding on the oats pasture system was more sensitive to a small decrease in the predicted price or the predicted live weight and therefore a riskier option than backgrounding on the other two systems. Outputs from the gross margin analyses were used in partial budgeting to illustrate a robust decision support framework that beef farmers can use for making decisions whether to sell weaners straight after weaning as opposed to selling after a period of backgrounding on pastures. Overall results indicate that backgrounding of calves on pastures has the potential to be a viable beef enterprise on smaller farms in the region. Keywords: beef production; Gompertz growth curves, feed intake; pasture backgrounding; gross margin; partial budgets.
- Full Text:
- Date Issued: 2020
- Authors: Terblanche, Ian
- Date: 2020
- Subjects: Calves -- Weaning -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/47623 , vital:40259
- Description: The backgrounding of beef weaner calves from pastures has the potential to be developed as an intensive beef enterprise that can increase the income of smaller farms, given that these farms have the ability to produce good quality pastures. This study was conducted to verify the inputs that impact on the viability of pasture backgrounding systems in an attempt to provide beef producers with better information for decision making. The scientific research was conducted with the registered Kromme Rhee Bonsmara herd at the Kromme Rhee research farm of the Western Cape Department of Agriculture. The farm is situated at 18º50’E and 33º51’S in the Stellenbosch area and has an altitude of 177 m above sea level. The area is situated in the winter rainfall region of the Western Cape with an annual rainfall of 670 mm. The average summer temperature ranges between 15-35 ºC and winter temperature between 10-17 ºC. The aim of this study was to develop growth curves representing the growth of Bonsmara animals for use by beef producers in predicting future live weight of animals in a pasture backgrounding system. Dry matter (DM) intake was measured at various live weight stages in order to determine whether a prediction model could be established to represent the DM intake of growing Bonsmara cattle on pastures. Results were used as inputs to determine whether backgrounding on pastures was economically viable. Animals were weighed at monthly intervals. Weighings commenced from birth and continued for a period of 797 days, repeated with two production year groups. One group consisted of 18 heifers and 12 bulls that were weighed from birth till an average age of 759 days. The other group consisted of four heifers and seven bulls and was weighed from birth untill an average age of 892 days. Roughage supplementation was done with lucerne hay in periods of pasture shortfalls, while a protein and energy lick were supplied continuously. A feeding trial with 10 weaned heifers and 10 bull calves of the same year group was conducted to determine the average feed intake per individual animal over a thirteen-month period that commenced after weaning. Two groups of five Bonsmara bull calves and two groups of five Bonsmara heifers were grouped according to age and gender. The feed intake of the growing calves was recorded for different live weight categories. The animals received lucerne (Medicago sativa) hay on an ad lib basis, while a concentrate supplement was supplied at 2 kg per animal per day up until live weights of 350 kg for heifers and 380 kg for bulls was achieved. The lucerne based diet was formulated to simulate a diet for growing animals on pasture with additional supplementation. Group feed intake values of the four groups of animals were measured at about 20-day intervals over the trial period of 369 days. The feed waste was dried and weighed back to calculate a waste percentage to be used as a correction factor. The Gompertz growth function was used to develop growth curves for male and female Bonsmara animals. Results indicated a significant difference between the mature weight of males and females (P <0.05). In both year groups the nonlinear Gompertz growth model predicted heavier mature weight for males compared to females. Mature weights of bulls were respectively 44.4% and 68.5% higher than that of heifers over the two year period. Days at maximum growth occurred later for males than for females (P <0.05) and the maturing rate of males and females did not differ significantly. Individual average feed intakes were calculated from the group fed animals over the duration of the rearing period. The data revealed that feed intake for bulls can be predicted by the linear model, DMI= 0.16531 + 0.0235306 x live weight (P ≤0.001; R 2 = 78.25). The feed intake of heifers can be predicted by the linear model, DMI= -1.41991 + 0.0283891 x live weight (P ≤0.001; R 2= 76.25). Analysis of variance detected no difference between the percentage feed intake of heifers (2.46%) and bulls (2.40%), over the experimental period. Prices of different live weight groupings were analysed over seven years to establish whether cyclical price trends can be observed across years and seasonal price trends within years. Within years prices were found to differ between months. For all calf weight groups, the lowest prices occurred in the months of March, April, May, June and July which showed price indices significantly different (P <0.05) from indices of the months of October, November and December when highest prices occurred, confirming seasonality in weaner calf prices. Price indices were developed for use as an input in the economic viability assessment. A brief literature review on the production and quality of four common pastures in the Southern Cape was done to gather information for compiling pasture budgets for use in determining the economic viability of pasture backgrounding. The economic viability of backgrounding on pastures was evaluated on a gross margin level and illustrated for three pasture systems namely irrigated oats as a winter pasture, irrigated lucerne as a spring pasture and dryland P. clandestinum /E. plana /mixed grass also as a low-cost spring pasture. All three pasture systems showed a positive economic viability for the decision parameters used in the illustration. The gross margin of backgrounding on the oats pasture system was more sensitive to a small decrease in the predicted price or the predicted live weight and therefore a riskier option than backgrounding on the other two systems. Outputs from the gross margin analyses were used in partial budgeting to illustrate a robust decision support framework that beef farmers can use for making decisions whether to sell weaners straight after weaning as opposed to selling after a period of backgrounding on pastures. Overall results indicate that backgrounding of calves on pastures has the potential to be a viable beef enterprise on smaller farms in the region. Keywords: beef production; Gompertz growth curves, feed intake; pasture backgrounding; gross margin; partial budgets.
- Full Text:
- Date Issued: 2020
Investigation of the interaction between truck tyre waste rubber particulate and penetration grade and polymer modified bituminous binders
- Authors: Mgangato, Siseko
- Date: 2020
- Subjects: Truck equipment industry
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/48500 , vital:40882
- Description: Recent studies have investigated the waste tyre crumb rubber (TCR)-bitumen interaction by observing the swelling of waste TCR at elevated temperatures. It was found that the waste TCR-bitumen interaction alters the rigidity and shape of TCR, which causes the failure of asphalt mixtures. Consequently, the problem occurs when the waste TCR swells during waste TCR-bitumen interaction from mixing and transportation of the asphalt mixture. Extensive laboratory studies have shown that the rate of absorption of bitumen is correlated with the TCR rubber composition and particle size. However, it is possible that swelling of waste TCR can be prevented or reduced before waste TCR-bitumen interaction by means of pre-treating the rubber crumb as to prevent the alteration of bitumen properties. Therefore, this study seeks to investigate the interaction of truck tyre wastes rubber particulates (WRP)-bitumen with the pretreatment of truck tyre WRP with H2SO4, HNO3 and HCℓ. This treatment was done to make TCR suitable for the dry process asphalt mixtures, where TCR acts as a filler instead of altering bitumen binder properties. The investigation characterized truck tyre WRP-bituminous binder interaction by interacting a single truck tyre WRP with penetration grade (50/70 and 70/100) and industrial polymer modified binders (AE-2 and PolyMod). The interaction through kinetic study revealed that the swelling of truck tyre WRP is either a non-Fickian two-step swelling or anomalous diffusion mechanism of bituminous binders. In addition, the study showed that temperature has an effect on the diffusion, sorption and permeation coefficients; where coefficients increased as the temperature was increased. The characterization of which bituminous binder component was observed by the truck tyre WRP was studied using Fourier Transform Infra-Red Spectroscopy (FTIR), Carbon 13 Nuclear Magnetic Spectroscopy (13C NMR) and Thermalgravimetric Analysis (TGA). The study showed that by analysing the extracted bituminous binder from residual truck tyre WRP after the interaction, Polycyclic Aromatic Hydrocarbons (PAHs) consisting of molecular structure characteristics of bitumen constituent aromatics. So as to restricting the diffusion of bituminous binder into truck tyre WRP, the surface of truck tyre WRP was treated with H2SO4, HNO3 and HCℓ acids from concentrations of 1, 6 and 12 M. The H2SO4 and HCℓ treated WRP showed a change in molecular ii structure, toluene sorption coefficient, surface morphology and thermal characteristics (TGA and DSC). However, changes that were observed with the HNO3 treatment showed that the truck tyre WRP material was in fact being digested by the HNO3 acid. In all the respective acid treatments, the effects were distinct with 12 M acid concentration. This was observed with a decrease in toluene sorption coefficient with increasing acid concentration. From the treatment of the truck tyre WRP with H2SO4, HNO3 and HCℓ acids, the 6 M acid concentration showed desirable characteristics. Interaction of the respective acid treated truck tyre WRP-bituminous binder interaction was carried out following the drainage basket method. In this investigation, the 6 M acid (H2SO4, HNO3 and HCℓ) treated WRP was used and it was found that swelling followed a two-stage and anomalous non-Fickian diffusion patterns. Hence HNO3 absorbed the least binders and this was confirmed by the low sorption coefficients. Although the H2SO4 and HCℓ did not show a significant difference with 50/70 and 70/100 and a significant change with AE-2 and PolyMod binder absorption, the dynamic shear rheometre (DSR) measurements revealed that the residual binders (50/70, 70/100, AE2 and PolyMod) had a higher rutting temperature than respective original binder, where G*/sinδ is ≤ 1 kPa. These binders also had lower fatigue to cracking temperature through analysis of G*sinδ at 5 000 kPa. In addition, the measured phase angle at the respective rutting temperature showed to be between 45 ̊and 90 ̊which suggested that the binders were viscoelastic. Viscoelastic characteristics were therefore assessed using multiple stress creep recovery test (MSCR). The measured MSCR parameters, % recovery and non-recoverable compliance, showed that there was a slight gain in elasticity with 50/70 and 70/100 after the interaction. The AE-2 and PolyMod binders experienced a decrease in elasticity after the interaction. Despite unforeseen outcomes, the treatment of truck tyre WRP with H2SO4, HNO3 and HCℓ acids decreased the swelling phenomenon of truck tyre WRP in a bituminous binder.
- Full Text:
- Date Issued: 2020
- Authors: Mgangato, Siseko
- Date: 2020
- Subjects: Truck equipment industry
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/48500 , vital:40882
- Description: Recent studies have investigated the waste tyre crumb rubber (TCR)-bitumen interaction by observing the swelling of waste TCR at elevated temperatures. It was found that the waste TCR-bitumen interaction alters the rigidity and shape of TCR, which causes the failure of asphalt mixtures. Consequently, the problem occurs when the waste TCR swells during waste TCR-bitumen interaction from mixing and transportation of the asphalt mixture. Extensive laboratory studies have shown that the rate of absorption of bitumen is correlated with the TCR rubber composition and particle size. However, it is possible that swelling of waste TCR can be prevented or reduced before waste TCR-bitumen interaction by means of pre-treating the rubber crumb as to prevent the alteration of bitumen properties. Therefore, this study seeks to investigate the interaction of truck tyre wastes rubber particulates (WRP)-bitumen with the pretreatment of truck tyre WRP with H2SO4, HNO3 and HCℓ. This treatment was done to make TCR suitable for the dry process asphalt mixtures, where TCR acts as a filler instead of altering bitumen binder properties. The investigation characterized truck tyre WRP-bituminous binder interaction by interacting a single truck tyre WRP with penetration grade (50/70 and 70/100) and industrial polymer modified binders (AE-2 and PolyMod). The interaction through kinetic study revealed that the swelling of truck tyre WRP is either a non-Fickian two-step swelling or anomalous diffusion mechanism of bituminous binders. In addition, the study showed that temperature has an effect on the diffusion, sorption and permeation coefficients; where coefficients increased as the temperature was increased. The characterization of which bituminous binder component was observed by the truck tyre WRP was studied using Fourier Transform Infra-Red Spectroscopy (FTIR), Carbon 13 Nuclear Magnetic Spectroscopy (13C NMR) and Thermalgravimetric Analysis (TGA). The study showed that by analysing the extracted bituminous binder from residual truck tyre WRP after the interaction, Polycyclic Aromatic Hydrocarbons (PAHs) consisting of molecular structure characteristics of bitumen constituent aromatics. So as to restricting the diffusion of bituminous binder into truck tyre WRP, the surface of truck tyre WRP was treated with H2SO4, HNO3 and HCℓ acids from concentrations of 1, 6 and 12 M. The H2SO4 and HCℓ treated WRP showed a change in molecular ii structure, toluene sorption coefficient, surface morphology and thermal characteristics (TGA and DSC). However, changes that were observed with the HNO3 treatment showed that the truck tyre WRP material was in fact being digested by the HNO3 acid. In all the respective acid treatments, the effects were distinct with 12 M acid concentration. This was observed with a decrease in toluene sorption coefficient with increasing acid concentration. From the treatment of the truck tyre WRP with H2SO4, HNO3 and HCℓ acids, the 6 M acid concentration showed desirable characteristics. Interaction of the respective acid treated truck tyre WRP-bituminous binder interaction was carried out following the drainage basket method. In this investigation, the 6 M acid (H2SO4, HNO3 and HCℓ) treated WRP was used and it was found that swelling followed a two-stage and anomalous non-Fickian diffusion patterns. Hence HNO3 absorbed the least binders and this was confirmed by the low sorption coefficients. Although the H2SO4 and HCℓ did not show a significant difference with 50/70 and 70/100 and a significant change with AE-2 and PolyMod binder absorption, the dynamic shear rheometre (DSR) measurements revealed that the residual binders (50/70, 70/100, AE2 and PolyMod) had a higher rutting temperature than respective original binder, where G*/sinδ is ≤ 1 kPa. These binders also had lower fatigue to cracking temperature through analysis of G*sinδ at 5 000 kPa. In addition, the measured phase angle at the respective rutting temperature showed to be between 45 ̊and 90 ̊which suggested that the binders were viscoelastic. Viscoelastic characteristics were therefore assessed using multiple stress creep recovery test (MSCR). The measured MSCR parameters, % recovery and non-recoverable compliance, showed that there was a slight gain in elasticity with 50/70 and 70/100 after the interaction. The AE-2 and PolyMod binders experienced a decrease in elasticity after the interaction. Despite unforeseen outcomes, the treatment of truck tyre WRP with H2SO4, HNO3 and HCℓ acids decreased the swelling phenomenon of truck tyre WRP in a bituminous binder.
- Full Text:
- Date Issued: 2020
The effect of top dressing treatments on stolon weaning and keeping quality on two potato cultivars in the Gamtoos river valley
- Authors: Murray, Roger Benjamin
- Date: 2020
- Subjects: Plants -- Effect of nitrates on
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/48522 , vital:40884
- Description: Potatoes are an important crop in the Eastern Cape, and in South Africa as a whole, as a nutritious staple food. For consumers, they provide a quality, relatively low-priced form of carbohydrate and, for farmers, they are a valuable cash crop. The nutritional requirements of Solanum tuberosum L., in particular its nitrogen (N) needs, during cultivation is an aspect warranting further research. The Eastern Cape is a prime potato-producing region and, as such, is an appropriate and logical choice in terms of a suitable location for the required study. Improper farming practices with regards to improper fertilizer application techniques can adversely affect yields, and excessive application of fertilizer is fundamentally economically unsound, adverse towards the environment and potentially detrimental to the crop. It is therefore imperative that nutrients – and nitrogen in particular – are available to the crop in the correct quantities at the correct time. The objective of this dissertation was to accurately identify the nitrogen fertilizer needs of potatoes – with specific emphasis on whether or not nitrogen affects stolon growth and development. The potato cultivar used in the research trial was Mondial, which is a cultivar well-established in the region. Nitrogen applications needed to be closely monitored with regards to the total seasonal amount of nitrogen applied, the timing of applications and the amount applied at each application. Meaningful data accumulated from this study will help farmers in the area to accurately assess the efficiency of their farming operations. Excessive or insufficient plant nutrition affects tuber bulking and quality. The objective was to accurately identify this “sweet spot” (i.e. the optimal measure and timing) with regards to fertilization, especially nitrogen, while also taking into account various other factors that affect healthy tuber development and stolon formation. The untested assertion that prompted this study was that too much nitrogen adversely affects the number of stolons – and therefore, the number of tubers, since tubers grow from the stolons. It is generally accepted that too little N will adversely affect yields and yield potential will not be achieved, and that too much N will adversely affect yields, incur unnecessary costs and potentially degrade the environment. Optimum nitrogen application quantities were therefore identified, along with points at which deviations from optimum yields occurred. There were 8 distinct treatment combinations – namely: a rate of 150kg/ha, 250kg/ha, 350kg/ha and 450kg/ha – of nitrogen (N) throughout the growing season, administered at 2 different timings (hereafter referred to as the Application Timings). The applications of nitrogen were administered as follows: Application Timing 1 (50% N at planting : 25% N as Topdressing 1 : 25% N as Topdressing 2) and Application Timing 2 (75% N at planting : 12.5% N as Topdressing 1 : 12.5% N as Topdressing 2). The findings suggest that while nitrogen played a role in increasing yield, there was no conclusive evidence to suggest that stolons were weaned by excessive amounts of nitrogen throughout the growing season. The results obtained from statistical analysis showed that, between Application Timing 1 (50%:25%:25%) and Application Timing 2 (75%:12.5%:12.5%), neither split application timing was superior to the other in terms of tuber yield or effect on the average number of stolons when data from all three plantings were combined. In some instances, high stolon numbers were observed in the high N application plots. The highest stolon count in a single data collection in Planting 1 was in the 450kg/ha App. 1 plots in the 3rd data collection. The highest stolon count in a single data collection in Planting 2 was in the 250kg/ha App. 2 plots in the 2nd data collection. The highest stolon count in a single data collection was in the 350kg/ha App. 2 plots in the 3rd data collection. The conjecture that excessive nitrogen causes stolon weaning in potatoes was not supported by the findings of the experiments conducted in the three trial plantings which constituted this research study.
- Full Text:
- Date Issued: 2020
- Authors: Murray, Roger Benjamin
- Date: 2020
- Subjects: Plants -- Effect of nitrates on
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/48522 , vital:40884
- Description: Potatoes are an important crop in the Eastern Cape, and in South Africa as a whole, as a nutritious staple food. For consumers, they provide a quality, relatively low-priced form of carbohydrate and, for farmers, they are a valuable cash crop. The nutritional requirements of Solanum tuberosum L., in particular its nitrogen (N) needs, during cultivation is an aspect warranting further research. The Eastern Cape is a prime potato-producing region and, as such, is an appropriate and logical choice in terms of a suitable location for the required study. Improper farming practices with regards to improper fertilizer application techniques can adversely affect yields, and excessive application of fertilizer is fundamentally economically unsound, adverse towards the environment and potentially detrimental to the crop. It is therefore imperative that nutrients – and nitrogen in particular – are available to the crop in the correct quantities at the correct time. The objective of this dissertation was to accurately identify the nitrogen fertilizer needs of potatoes – with specific emphasis on whether or not nitrogen affects stolon growth and development. The potato cultivar used in the research trial was Mondial, which is a cultivar well-established in the region. Nitrogen applications needed to be closely monitored with regards to the total seasonal amount of nitrogen applied, the timing of applications and the amount applied at each application. Meaningful data accumulated from this study will help farmers in the area to accurately assess the efficiency of their farming operations. Excessive or insufficient plant nutrition affects tuber bulking and quality. The objective was to accurately identify this “sweet spot” (i.e. the optimal measure and timing) with regards to fertilization, especially nitrogen, while also taking into account various other factors that affect healthy tuber development and stolon formation. The untested assertion that prompted this study was that too much nitrogen adversely affects the number of stolons – and therefore, the number of tubers, since tubers grow from the stolons. It is generally accepted that too little N will adversely affect yields and yield potential will not be achieved, and that too much N will adversely affect yields, incur unnecessary costs and potentially degrade the environment. Optimum nitrogen application quantities were therefore identified, along with points at which deviations from optimum yields occurred. There were 8 distinct treatment combinations – namely: a rate of 150kg/ha, 250kg/ha, 350kg/ha and 450kg/ha – of nitrogen (N) throughout the growing season, administered at 2 different timings (hereafter referred to as the Application Timings). The applications of nitrogen were administered as follows: Application Timing 1 (50% N at planting : 25% N as Topdressing 1 : 25% N as Topdressing 2) and Application Timing 2 (75% N at planting : 12.5% N as Topdressing 1 : 12.5% N as Topdressing 2). The findings suggest that while nitrogen played a role in increasing yield, there was no conclusive evidence to suggest that stolons were weaned by excessive amounts of nitrogen throughout the growing season. The results obtained from statistical analysis showed that, between Application Timing 1 (50%:25%:25%) and Application Timing 2 (75%:12.5%:12.5%), neither split application timing was superior to the other in terms of tuber yield or effect on the average number of stolons when data from all three plantings were combined. In some instances, high stolon numbers were observed in the high N application plots. The highest stolon count in a single data collection in Planting 1 was in the 450kg/ha App. 1 plots in the 3rd data collection. The highest stolon count in a single data collection in Planting 2 was in the 250kg/ha App. 2 plots in the 2nd data collection. The highest stolon count in a single data collection was in the 350kg/ha App. 2 plots in the 3rd data collection. The conjecture that excessive nitrogen causes stolon weaning in potatoes was not supported by the findings of the experiments conducted in the three trial plantings which constituted this research study.
- Full Text:
- Date Issued: 2020
A comparison of different strategies to control pests and diseases in Brassica spp. production in the Western Cape
- Van Niekerk, Abraham Johannes
- Authors: Van Niekerk, Abraham Johannes
- Date: 2019
- Subjects: Pesticides , Pests -- Control Agricultural pests , Plant diseases
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/44122 , vital:37113
- Description: Brassica spp. are cultivated all over the world, commercial species include: cabbage, broccoli, kale, kohlrabi and turnip. In this study the focus was on broccoli (Brassica oleracea) production in the Western Cape province of South Africa and its economically important pests and diseases: sugar beet cyst nematode (Heterodera schachtii), diamondback moth (Plutella xylostella), white blister (Albugo candida) and clubroot (Plasmodiophora brassicae), and the different methods to control these pests and diseases. The control methods focused on in this study included a commercial chemical control programme, a biological control programme and a holistic approach. Other factors were bio-fumigation and chemical fumigation and different crop rotation practices including rotation crops versus no rotation crops. The experimental design was a strip split plot design, with different pest and disease management strategies as the main plot treatment and fumigation and rotation treatment combinations arranged in strips across the main plot treatments. The main plot design was a randomized complete block with four programmes (Control, Holistic, Chemical and Biological) replicated four times and laid out in a Randomised Complete Block Design (RCBD). The treatment design of the strip plot factors was a 2x2 factorial with two fumigations (fumigated chemically and fumigated biologically) and two rotations (crop rotated and monoculture) randomly allocated across main plot treatments. Each experimental unit consisted of 40 plants. Plants were evaluated weekly for the incidence of white blister and diamondback moth. Incidences of clubroot and white blister infection of heads of broccoli were recorded 78 days after planting. Baseline soil samples were analysed to establish the soil chemical properties. Post-trial soil samples were also analysed to investigate the effect of the different practices and programmes on the soil chemical properties. Nematodes were extracted pre-trial and post-trial, and the effect of fumigation and crop rotation on plant parasitic nematodes and the nematode population diversity investigated. In the post-trial soil chemical analysis, a significantly higher concentration of Na was recorded for the biological programme when crop rotation was included compared to the no rotation treatment. The concentration of K was also significantly higher in the no rotation compared to the rotation treatment. The nematode results showed very high numbers of bacterial feeders in all the samples. Overall nematode diversity was lacking and showed very few fungal feeders, omnivores and predators. The nematode indices for all of the samples showed that nematodes were highly enriched and unstructured. Of the plant parasitic nematodes, only Heterodera spp. were obtained in the pre-trial analysis, and incidences of these nematodes were lower at the end of the trial. Low numbers of other plant parasitic nematodes viz. Pratylenchus, Paratrichodorus and Tylenchorhynchus were reported for the post-trial analysis of the soil. Because of the low numbers of plant parasitic nematodes, it was not possible to analyse the data statistically. With regard to diamondback moth and the fungal diseases, crop rotation and fumigation did not significantly affect the incidence of white blister and diamondback moth. A significant “days after planting by control programme” interaction was reported for the incidence of white blister on foliage and the incidence of diamondback moth. All three control programmes significantly reduced the incidence of diamondback moth with the chemical programme being significantly more effective than the other two programmes. All three programmes also significantly reduced the incidence of white blister on foliage and the holistic and biological programmes significantly reduced the incidence of white blister on broccoli heads with the holistic programme being significantly more effective than the biological programme. There was no clubroot infection in the trial for any of the treatments. Results of this study showed that it is possible to manage diseases and pests of broccoli using a holistic approach. However, long term trials are needed to confirm the results obtained in this study.
- Full Text:
- Date Issued: 2019
- Authors: Van Niekerk, Abraham Johannes
- Date: 2019
- Subjects: Pesticides , Pests -- Control Agricultural pests , Plant diseases
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/44122 , vital:37113
- Description: Brassica spp. are cultivated all over the world, commercial species include: cabbage, broccoli, kale, kohlrabi and turnip. In this study the focus was on broccoli (Brassica oleracea) production in the Western Cape province of South Africa and its economically important pests and diseases: sugar beet cyst nematode (Heterodera schachtii), diamondback moth (Plutella xylostella), white blister (Albugo candida) and clubroot (Plasmodiophora brassicae), and the different methods to control these pests and diseases. The control methods focused on in this study included a commercial chemical control programme, a biological control programme and a holistic approach. Other factors were bio-fumigation and chemical fumigation and different crop rotation practices including rotation crops versus no rotation crops. The experimental design was a strip split plot design, with different pest and disease management strategies as the main plot treatment and fumigation and rotation treatment combinations arranged in strips across the main plot treatments. The main plot design was a randomized complete block with four programmes (Control, Holistic, Chemical and Biological) replicated four times and laid out in a Randomised Complete Block Design (RCBD). The treatment design of the strip plot factors was a 2x2 factorial with two fumigations (fumigated chemically and fumigated biologically) and two rotations (crop rotated and monoculture) randomly allocated across main plot treatments. Each experimental unit consisted of 40 plants. Plants were evaluated weekly for the incidence of white blister and diamondback moth. Incidences of clubroot and white blister infection of heads of broccoli were recorded 78 days after planting. Baseline soil samples were analysed to establish the soil chemical properties. Post-trial soil samples were also analysed to investigate the effect of the different practices and programmes on the soil chemical properties. Nematodes were extracted pre-trial and post-trial, and the effect of fumigation and crop rotation on plant parasitic nematodes and the nematode population diversity investigated. In the post-trial soil chemical analysis, a significantly higher concentration of Na was recorded for the biological programme when crop rotation was included compared to the no rotation treatment. The concentration of K was also significantly higher in the no rotation compared to the rotation treatment. The nematode results showed very high numbers of bacterial feeders in all the samples. Overall nematode diversity was lacking and showed very few fungal feeders, omnivores and predators. The nematode indices for all of the samples showed that nematodes were highly enriched and unstructured. Of the plant parasitic nematodes, only Heterodera spp. were obtained in the pre-trial analysis, and incidences of these nematodes were lower at the end of the trial. Low numbers of other plant parasitic nematodes viz. Pratylenchus, Paratrichodorus and Tylenchorhynchus were reported for the post-trial analysis of the soil. Because of the low numbers of plant parasitic nematodes, it was not possible to analyse the data statistically. With regard to diamondback moth and the fungal diseases, crop rotation and fumigation did not significantly affect the incidence of white blister and diamondback moth. A significant “days after planting by control programme” interaction was reported for the incidence of white blister on foliage and the incidence of diamondback moth. All three control programmes significantly reduced the incidence of diamondback moth with the chemical programme being significantly more effective than the other two programmes. All three programmes also significantly reduced the incidence of white blister on foliage and the holistic and biological programmes significantly reduced the incidence of white blister on broccoli heads with the holistic programme being significantly more effective than the biological programme. There was no clubroot infection in the trial for any of the treatments. Results of this study showed that it is possible to manage diseases and pests of broccoli using a holistic approach. However, long term trials are needed to confirm the results obtained in this study.
- Full Text:
- Date Issued: 2019
Comparison of consumer perspectives of the natural and commercial synthetic chemical-based mosquito repellent products
- Authors: Ndoyana, Lusanda
- Date: 2019
- Subjects: Insect baits and repellents , Mosquitoes -- Control Consumers -- Attitudes Consumers -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/42902 , vital:36704
- Description: The present study was conducted to determine the perceptions of consumers between the natural mosquito repellent products and the synthetic chemical mosquito repellent products. The perception is that natural mosquito repellent products are more effective than synthetic chemical mosquito repellents based on odour, cost and quality. A comparison of the two products was done in a form of a structured questionnaire where randomly selected participants were given two questionnaires. The participants were asked to provide their perceptions concerning cost, quality and odour. Each participant was also given one formulated natural (green) candle and one synthetic (white) chemical mosquito repellent product. The formulated natural candles contain Oil of Lemon Eucalyptus (OLE) as the active ingredient. OLE is a natural plant-based repellent which is extracted from the leaves and twigs of the lemon-scented gum eucalyptus plant. The results showed that both products were effective in terms of cost, product quality and odour. However, the natural mosquito repellent product was more effective than the synthetic chemical product based on the observed p-value results.
- Full Text:
- Date Issued: 2019
- Authors: Ndoyana, Lusanda
- Date: 2019
- Subjects: Insect baits and repellents , Mosquitoes -- Control Consumers -- Attitudes Consumers -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/42902 , vital:36704
- Description: The present study was conducted to determine the perceptions of consumers between the natural mosquito repellent products and the synthetic chemical mosquito repellent products. The perception is that natural mosquito repellent products are more effective than synthetic chemical mosquito repellents based on odour, cost and quality. A comparison of the two products was done in a form of a structured questionnaire where randomly selected participants were given two questionnaires. The participants were asked to provide their perceptions concerning cost, quality and odour. Each participant was also given one formulated natural (green) candle and one synthetic (white) chemical mosquito repellent product. The formulated natural candles contain Oil of Lemon Eucalyptus (OLE) as the active ingredient. OLE is a natural plant-based repellent which is extracted from the leaves and twigs of the lemon-scented gum eucalyptus plant. The results showed that both products were effective in terms of cost, product quality and odour. However, the natural mosquito repellent product was more effective than the synthetic chemical product based on the observed p-value results.
- Full Text:
- Date Issued: 2019
Development of polypropylene – waste tyre crumbs based tpe's with the aid of vistamaxxtm as a compatibiliser
- Authors: Masele, Siyamtanda
- Date: 2019
- Subjects: Polymers , Polymerization Crumb rubber Rubber
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/42589 , vital:36670
- Description: Polypropylene (PP) is a semi crystalline thermoplastic polymer and one of the most commonly used polyolefins. It is well known for its poor impact resistance; hence, for industries such as the automotive and packaging, reinforced PP is widely used. In general plastic waste disposal is a global crisis raising environmental and human health concerns, with PP being the highest consumed polymer globally; hence a push in the reuse and recycling of PP. Recycled polypropylene has limited uses for industrial applications due to its highly reduced properties owing to the recycling process which inhabits cutting of chains lengths, broadened molecular weight distributions and compromised crystallinity. Several studies have investigated the use of reinforcing fillers and modifiers in order to improve properties of PP. Inorganic materials and minerals such as CaCO3, Mica, Talc and glass fibre are used as fillers to improve mechanical properties (tensile and hardness), but still lacks in improving the impact resistance. Thermoplastic elastomers (TPE) are typically used where elastomer and thermoplastics fail as individual components. This is because they have the benefit of thermoplastic properties at hypo ambient condition and elastomer properties such as good impact and elongation at sub-zero conditions. The study took a route of using PP and waste tyre crumb rubber (CR) material to prepare potentially low-cost waste based TPE’s, which would then inherit both properties of PP and the rubber component. VistamaxxTM 6202 (EPR), a commercial name for ethylene-propylene monomer (EPR), was used as a compatibiliser to improve interaction between PP and CR and to contribute towards the overall improvement of various properties such as mechanical properties. VistamaxxTM has a low glass transition temperature (Tg, = -30 ºC), which is important for low temperature applications such as cold storage; it also has a very high elongation and as a result contributed significantly to the overall properties when used in TPE blends. The study highlighted differences between two TPE compounding formulation pathways; namely master-batch (MB) and design of experiments (DoE). The MB formulations were blends that were prepared by a conventional way of compounding; where a pre-mixed CR/EPR blend, in the ratio of 80(CR):20(EPR), was used to form a master-batch. Results showed that there are some similarities between TPEs prepared in different ways, which suggests that the ultimate properties such as thermal stability are in fact more PP matrix based. Thermal analyses results revealed that when high amount of CR was added to the TPE blends, there was a substantial amount of residue mainly due to inherent carbon black. The degree of crystallinity of the blends decreased with increased amounts of CR irrespective of whether it was the MB or DoE blends. The MB TPE blends demonstrated that hardness is not linked to the amount of the MB nor the crystallinity of blends. Meanwhile, tensile elongation and tensile stress were affected by crystallinity. On the other hand, the impact strength findings showed that the amount of MB in TPE blends reached a threshold at 30%. The DoE based TPE blends demonstrated that the optimum mechanical properties are observed when components of the blends are incorporated individually during compounding. This was observed for impact strength, tensile stress as well as elongation at break. The results showed that the incorporation of EPR should be at least 20% for good impact and elongation properties; however, for tensile and hardness, the PP matrix must be high. The study also showed that, for better mechanical properties it was more suitable to use the blends formulated with DoE, because the master-batch approach limited the improving of the mechanical properties by an addition of up to 30% of both the CR and EPR. The storage modulus as well as the tan delta for both MB and DoE decreased when the elastomeric phases were added on both methods, whereas tan delta Tg values decreased as more of the elastomeric phase was added. Evidence from morphology studies showed that the majority of TPE blends suffer from inadequate distribution and adhesion between PP and elastomer; resulting in poor mechanical properties. Furthermore, a threshold of matrix invasion is observed from 30% and above of CR in the blend, where lack of in capsulated lamps of CR were observed hindering the stress induced crystallization and relaxation of the PP phase. The latter was observed irrespective of the type of blend, which strongly suggests and highlights the limits of blending PP with elastomers. Study demonstrated the ability of VistamaxxTM to be utilized as a binding material for PP and CR and displaying the challenges that might arise when used as a master-batch with crumb rubber.
- Full Text:
- Date Issued: 2019
- Authors: Masele, Siyamtanda
- Date: 2019
- Subjects: Polymers , Polymerization Crumb rubber Rubber
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/42589 , vital:36670
- Description: Polypropylene (PP) is a semi crystalline thermoplastic polymer and one of the most commonly used polyolefins. It is well known for its poor impact resistance; hence, for industries such as the automotive and packaging, reinforced PP is widely used. In general plastic waste disposal is a global crisis raising environmental and human health concerns, with PP being the highest consumed polymer globally; hence a push in the reuse and recycling of PP. Recycled polypropylene has limited uses for industrial applications due to its highly reduced properties owing to the recycling process which inhabits cutting of chains lengths, broadened molecular weight distributions and compromised crystallinity. Several studies have investigated the use of reinforcing fillers and modifiers in order to improve properties of PP. Inorganic materials and minerals such as CaCO3, Mica, Talc and glass fibre are used as fillers to improve mechanical properties (tensile and hardness), but still lacks in improving the impact resistance. Thermoplastic elastomers (TPE) are typically used where elastomer and thermoplastics fail as individual components. This is because they have the benefit of thermoplastic properties at hypo ambient condition and elastomer properties such as good impact and elongation at sub-zero conditions. The study took a route of using PP and waste tyre crumb rubber (CR) material to prepare potentially low-cost waste based TPE’s, which would then inherit both properties of PP and the rubber component. VistamaxxTM 6202 (EPR), a commercial name for ethylene-propylene monomer (EPR), was used as a compatibiliser to improve interaction between PP and CR and to contribute towards the overall improvement of various properties such as mechanical properties. VistamaxxTM has a low glass transition temperature (Tg, = -30 ºC), which is important for low temperature applications such as cold storage; it also has a very high elongation and as a result contributed significantly to the overall properties when used in TPE blends. The study highlighted differences between two TPE compounding formulation pathways; namely master-batch (MB) and design of experiments (DoE). The MB formulations were blends that were prepared by a conventional way of compounding; where a pre-mixed CR/EPR blend, in the ratio of 80(CR):20(EPR), was used to form a master-batch. Results showed that there are some similarities between TPEs prepared in different ways, which suggests that the ultimate properties such as thermal stability are in fact more PP matrix based. Thermal analyses results revealed that when high amount of CR was added to the TPE blends, there was a substantial amount of residue mainly due to inherent carbon black. The degree of crystallinity of the blends decreased with increased amounts of CR irrespective of whether it was the MB or DoE blends. The MB TPE blends demonstrated that hardness is not linked to the amount of the MB nor the crystallinity of blends. Meanwhile, tensile elongation and tensile stress were affected by crystallinity. On the other hand, the impact strength findings showed that the amount of MB in TPE blends reached a threshold at 30%. The DoE based TPE blends demonstrated that the optimum mechanical properties are observed when components of the blends are incorporated individually during compounding. This was observed for impact strength, tensile stress as well as elongation at break. The results showed that the incorporation of EPR should be at least 20% for good impact and elongation properties; however, for tensile and hardness, the PP matrix must be high. The study also showed that, for better mechanical properties it was more suitable to use the blends formulated with DoE, because the master-batch approach limited the improving of the mechanical properties by an addition of up to 30% of both the CR and EPR. The storage modulus as well as the tan delta for both MB and DoE decreased when the elastomeric phases were added on both methods, whereas tan delta Tg values decreased as more of the elastomeric phase was added. Evidence from morphology studies showed that the majority of TPE blends suffer from inadequate distribution and adhesion between PP and elastomer; resulting in poor mechanical properties. Furthermore, a threshold of matrix invasion is observed from 30% and above of CR in the blend, where lack of in capsulated lamps of CR were observed hindering the stress induced crystallization and relaxation of the PP phase. The latter was observed irrespective of the type of blend, which strongly suggests and highlights the limits of blending PP with elastomers. Study demonstrated the ability of VistamaxxTM to be utilized as a binding material for PP and CR and displaying the challenges that might arise when used as a master-batch with crumb rubber.
- Full Text:
- Date Issued: 2019
Top-soil water retention in organic and conventional farming systems in South Africa’s Southern Cape
- Authors: Eckert, Catherine Jessica
- Date: 2019
- Subjects: Water harvesting , Soil moisture conservation Organic farming Sustainable agriculture
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/39885 , vital:35500
- Description: With the world’s growing population and limited natural resources, there is a need to produce more food using less inputs. A major limiting factor to meeting the agricultural production needs of the growing population is fresh water. Water is a critical resource in agriculture and may be more of a limiting factor than other crop growth requirements in some areas. Furthermore, water availability is being impacted by climate change and competition from other industries. Methods of improving crop water use efficiency through conservation of water and the enhancement of crop growth need to be employed to meet the growing demand sustainably. The purpose of the research was to assess the differences in soil water status between organically farmed crops with a grass mulch and conventionally farmed crops without mulch, with a view to making more efficient use of the water resource. This research was conducted at the Mandela long term organic farming systems research trial site at Nelson Mandela University, George campus in the southern Cape, South Africa. It is part of a larger research project (the Mandela Trials) in which various researchers have been involved in different aspects of this trial including agronomy, microbiology and pest and disease control. This research took place over two seasons, namely, 2016-2017 season and 2017-2018 season. The soil water content (SWC) of organic and conventional plots were measured using fixed capacitance probes that recorded continuous data, every half hour, at depths of 10, 30 and 50 cm. A handheld theta probe was also used to measure the SWC in the top 6 cm of the soil at 7 to14 day intervals. The organic treatment had a significantly higher SWC than the conventional treatment over the two seasons in which this research was conducted. In addition, soil carbon was significantly higher in the organic treatment, than the conventional. Organic farming methods preserve and promote an increase in soil organic matter, thus improving the soil structure and increasing the soil’s water holding capacity. From this research, it is concluded that organic farming practices can be used to help conserve SWC, keeping it available to crops for longer and helping farmers make more efficient use of this scarce resource. This is especially relevant for low rainfall areas which are affected by water shortages. The improved SWC availability should be coupled with good agronomic practices to increase productive water losses and the conversion of water to yields, thus increasing water use efficiency. In addition, adding organic matter to the soil will improve resilience of the soil and help sequester carbon and thus help in mitigating climate change.
- Full Text:
- Date Issued: 2019
Top-soil water retention in organic and conventional farming systems in South Africa’s Southern Cape
- Authors: Eckert, Catherine Jessica
- Date: 2019
- Subjects: Water harvesting , Soil moisture conservation Organic farming Sustainable agriculture
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/39885 , vital:35500
- Description: With the world’s growing population and limited natural resources, there is a need to produce more food using less inputs. A major limiting factor to meeting the agricultural production needs of the growing population is fresh water. Water is a critical resource in agriculture and may be more of a limiting factor than other crop growth requirements in some areas. Furthermore, water availability is being impacted by climate change and competition from other industries. Methods of improving crop water use efficiency through conservation of water and the enhancement of crop growth need to be employed to meet the growing demand sustainably. The purpose of the research was to assess the differences in soil water status between organically farmed crops with a grass mulch and conventionally farmed crops without mulch, with a view to making more efficient use of the water resource. This research was conducted at the Mandela long term organic farming systems research trial site at Nelson Mandela University, George campus in the southern Cape, South Africa. It is part of a larger research project (the Mandela Trials) in which various researchers have been involved in different aspects of this trial including agronomy, microbiology and pest and disease control. This research took place over two seasons, namely, 2016-2017 season and 2017-2018 season. The soil water content (SWC) of organic and conventional plots were measured using fixed capacitance probes that recorded continuous data, every half hour, at depths of 10, 30 and 50 cm. A handheld theta probe was also used to measure the SWC in the top 6 cm of the soil at 7 to14 day intervals. The organic treatment had a significantly higher SWC than the conventional treatment over the two seasons in which this research was conducted. In addition, soil carbon was significantly higher in the organic treatment, than the conventional. Organic farming methods preserve and promote an increase in soil organic matter, thus improving the soil structure and increasing the soil’s water holding capacity. From this research, it is concluded that organic farming practices can be used to help conserve SWC, keeping it available to crops for longer and helping farmers make more efficient use of this scarce resource. This is especially relevant for low rainfall areas which are affected by water shortages. The improved SWC availability should be coupled with good agronomic practices to increase productive water losses and the conversion of water to yields, thus increasing water use efficiency. In addition, adding organic matter to the soil will improve resilience of the soil and help sequester carbon and thus help in mitigating climate change.
- Full Text:
- Date Issued: 2019
Extraction of diallyl sulfides and other similar compounds from tulbaghia violacea, a South African plant, for potential use as devulcanizing agents
- Authors: Sonti, Thembela Celia
- Date: 2018
- Subjects: Violaceae -- South Africa , Plant extracts Plant products Traditional medicine
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/23338 , vital:30533
- Description: Tulbaghia violacea is a plant that is commonly used for traditional medicine in the Eastern Cape and Kwa-Zulu Natal Provinces of South Africa for treatment of ailments, such as fever, colds, asthma, tuberculosis, stomach-ache and cancer of the oesophagus. This plant has been found to be rich in sulfur-containing compounds that may display good potential as devulcanizing agents. Commonly used chemical devulcanizing agents are disulfides, such as diphenyl disulfide. These have been found to be relatively expensive compared to other methods of devulcanization. This study aimed to show that the sulfur- containing compounds extracted from the readily available Tulbaghia violacea plant can be used as devulcanizing agents. The presence of sulfur-containing compounds in the plant was positively identified by qualitative phytochemical analysis. Extraction of sulfur-containing compounds from the bulk plant material was successfully performed using the Soxhlet extraction method with a 2% 2-propanol in n-hexane solvent mixture. There was a positive identification of sulfur compounds in the crude extracts of the bulbs, roots and leaves. Diallyl disulfides (DADS) extracted from the plant were successfully quantified using normal phase high-performance liquid chromatography (HPLC). The results showed that in a bulb crude extract of 9.89 mg/mL concentration, there was 7.74X10-2 mg/mL concentration of DADS. In the roots crude extract of 10.26 mg/mL concentration, there was 2.93X10-2 mg/mL concentration of DADS; and in leaves crude extract of 10.47 mg/mL concentration, there was 3.69X10-2 mg/mL concentration of DADS. The crude extracts were evaluated for their effectiveness as devulcanizing agents by reacting them with vulcanized 2,3-dimethyl-2-butene (TME), which was used as a model compound. A reverse phase HPLC method was used to identify crosslink species formed during vulcanization, and to monitor the broken crosslinks during devulcanization. It was observed that the di- and polysulfidic crosslinked vulcanized model compound species were not present in the devulcanized product. Furthermore monosulfidic crosslink species, a common end species of devulcanization, were observed to increase in concentration from the HPLC chromatograms. It was observed that the extracts from the bulbs and leaves of Tulbaghia violacea were more effective than the extract from the roots when applied to the vulcanized model compound. This study demonstrates that Tulbaghia violacea can be used as alternatives to petroleum-derived chemicals as devulcanizing agents.
- Full Text:
- Date Issued: 2018
- Authors: Sonti, Thembela Celia
- Date: 2018
- Subjects: Violaceae -- South Africa , Plant extracts Plant products Traditional medicine
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/23338 , vital:30533
- Description: Tulbaghia violacea is a plant that is commonly used for traditional medicine in the Eastern Cape and Kwa-Zulu Natal Provinces of South Africa for treatment of ailments, such as fever, colds, asthma, tuberculosis, stomach-ache and cancer of the oesophagus. This plant has been found to be rich in sulfur-containing compounds that may display good potential as devulcanizing agents. Commonly used chemical devulcanizing agents are disulfides, such as diphenyl disulfide. These have been found to be relatively expensive compared to other methods of devulcanization. This study aimed to show that the sulfur- containing compounds extracted from the readily available Tulbaghia violacea plant can be used as devulcanizing agents. The presence of sulfur-containing compounds in the plant was positively identified by qualitative phytochemical analysis. Extraction of sulfur-containing compounds from the bulk plant material was successfully performed using the Soxhlet extraction method with a 2% 2-propanol in n-hexane solvent mixture. There was a positive identification of sulfur compounds in the crude extracts of the bulbs, roots and leaves. Diallyl disulfides (DADS) extracted from the plant were successfully quantified using normal phase high-performance liquid chromatography (HPLC). The results showed that in a bulb crude extract of 9.89 mg/mL concentration, there was 7.74X10-2 mg/mL concentration of DADS. In the roots crude extract of 10.26 mg/mL concentration, there was 2.93X10-2 mg/mL concentration of DADS; and in leaves crude extract of 10.47 mg/mL concentration, there was 3.69X10-2 mg/mL concentration of DADS. The crude extracts were evaluated for their effectiveness as devulcanizing agents by reacting them with vulcanized 2,3-dimethyl-2-butene (TME), which was used as a model compound. A reverse phase HPLC method was used to identify crosslink species formed during vulcanization, and to monitor the broken crosslinks during devulcanization. It was observed that the di- and polysulfidic crosslinked vulcanized model compound species were not present in the devulcanized product. Furthermore monosulfidic crosslink species, a common end species of devulcanization, were observed to increase in concentration from the HPLC chromatograms. It was observed that the extracts from the bulbs and leaves of Tulbaghia violacea were more effective than the extract from the roots when applied to the vulcanized model compound. This study demonstrates that Tulbaghia violacea can be used as alternatives to petroleum-derived chemicals as devulcanizing agents.
- Full Text:
- Date Issued: 2018
Phytochemical analysis and biological activity studies of an Eastern Cape medicinal plant, Strychnos Henningsii
- Authors: Mngoma, Mondeli
- Date: 2018
- Subjects: Medicinal plants -- South Africa -- Eastern Cape , Traditional medicine -- South Africa -- Eastern Cape Plants -- South Africa -- Eastern Cape -- Analysis
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/22758 , vital:30074
- Description: This project sees the chemical investigation of an Eastern Cape medicinal plant, Strychnos henningsii. The aim of this project was to investigate the phytoconstituents and activity of organic extracts of S. henningsii as well as isolation and characterization of single compounds. S. henningsii is one of the most widely used tree bark in the Eastern Cape in treating a variety of ailments. Evaluation of the traditional herbal use of the S. henningsii bark was warranted. Both the ethyl acetate and methanol extract proved to possess non-toxic properties and showed cell growth potential at low concentrations. The anti-inflammatory response of both extracts showed appreciable results, and they did not promote inflammatory due to the alkaloidal presence. Although the extracts both showed the presence of phenols, the anti-oxidant capacity by DPPH, FRAP, and ORAC assays was considerately lower than expected. The ethyl acetate extract presented a compound thought to be a terpenoid (4.1). Three compounds were isolated from the methanol extract; two alkaloidal compounds and one acrylate. The alkaloids were isolated from the methanol extract, stryvomicine (4.2) and an isovomicine derivative (4.3). Their structures were deduced from NMR (1D and 2D experiments) and HRMS spectra. This acrylate was found to be 3-(4-methylphenyl)acrylic acid via single-crystal XRD, and this is the first report of it being isolated from the Strychnos genus. Profiling of S. henningsii was performed via Liquid Chromatography–Mass Spectroscopy. Other spectroscopic techniques utilised in the interpretation of isolated compounds included Nuclear Magnetic Resonance, Infrared, single-crystal X-Ray Diffraction and High Resolution Mass spectroscopy.
- Full Text:
- Date Issued: 2018
- Authors: Mngoma, Mondeli
- Date: 2018
- Subjects: Medicinal plants -- South Africa -- Eastern Cape , Traditional medicine -- South Africa -- Eastern Cape Plants -- South Africa -- Eastern Cape -- Analysis
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/22758 , vital:30074
- Description: This project sees the chemical investigation of an Eastern Cape medicinal plant, Strychnos henningsii. The aim of this project was to investigate the phytoconstituents and activity of organic extracts of S. henningsii as well as isolation and characterization of single compounds. S. henningsii is one of the most widely used tree bark in the Eastern Cape in treating a variety of ailments. Evaluation of the traditional herbal use of the S. henningsii bark was warranted. Both the ethyl acetate and methanol extract proved to possess non-toxic properties and showed cell growth potential at low concentrations. The anti-inflammatory response of both extracts showed appreciable results, and they did not promote inflammatory due to the alkaloidal presence. Although the extracts both showed the presence of phenols, the anti-oxidant capacity by DPPH, FRAP, and ORAC assays was considerately lower than expected. The ethyl acetate extract presented a compound thought to be a terpenoid (4.1). Three compounds were isolated from the methanol extract; two alkaloidal compounds and one acrylate. The alkaloids were isolated from the methanol extract, stryvomicine (4.2) and an isovomicine derivative (4.3). Their structures were deduced from NMR (1D and 2D experiments) and HRMS spectra. This acrylate was found to be 3-(4-methylphenyl)acrylic acid via single-crystal XRD, and this is the first report of it being isolated from the Strychnos genus. Profiling of S. henningsii was performed via Liquid Chromatography–Mass Spectroscopy. Other spectroscopic techniques utilised in the interpretation of isolated compounds included Nuclear Magnetic Resonance, Infrared, single-crystal X-Ray Diffraction and High Resolution Mass spectroscopy.
- Full Text:
- Date Issued: 2018
Evaluation of near infrared reflectance (NIR) spectroscopy to determine the nutrient composition of raw materials and compound ostrich feeds
- Swart, Etheresia, Lehmann-Maritz, Maryna
- Authors: Swart, Etheresia , Lehmann-Maritz, Maryna
- Date: 2017
- Subjects: Near infrared spectroscopy , Animal nutrition , Animal feeding
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/13779 , vital:27307
- Description: The chemical analysis of feed samples can be time consuming and expensive. The use of near infrared reflectance (NIR) spectroscopy was evaluated in a range of studies as a rapid technique to predict the chemical constituents in feedstuffs and compound ostrich feeds. The prediction of accurate results by NIR spectroscopy relies heavily upon obtaining a calibration set which represents the variation in the main population, accurate laboratory analyses and the application of the best mathematical procedures. This research project was designed to meet five objectives: The first objective was to determine the feasibility of using near infrared reflectance (NIR) spectroscopy to predict dry matter, ash, crude protein, crude fibre, oil content, and fatty acids such as palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1) and linoleic acid (C18:2) in sunflower seed meal. The second objective was to develop calibration models to predict the dry matter, crude protein and oil content in milled canola seed, compared to whole canola seeds. The third objective was to investigate the feasibility of using NIR spectroscopy to predict the dry matter, ash, crude protein, crude fibre and oil content in milled lupin seeds, compared to whole lupin seeds. The fourth objective was to describe the development of near infrared reflectance (NIR) spectroscopy calibration equations for the prediction of chemical composition and amino acid content from different populations of alfalfa hay (Medicago sativa L.). The last objective was to determine the potential of NIR spectroscopy to predict the dry matter, ash, crude protein, crude fibre, ether extract, acid detergent fibre (ADF), neutral detergent fibre (NDF), calcium, phosphorus, in vitro organic matter digestibility (IVOMD) and amino acids such as lysine, methionine, threonine and arginine in compound ostrich feed samples. The results of this study indicate that NIR spectroscopy calibrations in sunflower seed meal are only applicable in sunflower breeding programmes for a fast screening as it was not suitable for prediction purposes. Screening of sunflower seeds by NIR spectroscopy represents a rapid, simple and cost effective alternative that is a great utility for users who need to analyse a large number of samples. Calibrations developed for crude protein and oil content in milled canola seeds proved to be better than calibrations for whole canola seeds. Although the results indicated that calibrations were better for milled canola seeds, it indicated values that were typical of equations suitable for screening purposes to select samples for more detailed chemical analysis. According to calibration statistics obtained for crude protein, crude fibre and oil content in whole lupin seeds, there is no need to grind the seeds to scan the meal as similarly accurate results were obtained by analysing whole seeds. Screening of whole lupin seeds by NIR spectroscopy represents a rapid, simple and cost effective alternative that may be of great utility for users who need to analyse a large number of samples with no sample preparation. The calibration and validation statistics obtained in the study to test the potential of NIR spectroscopy to predict the chemical composition and amino acid contents in alfalfa hay, showed the accuracy was too low for routine analysis, although NIR spectroscopy could be used as a screening tool. Further research needs to be done to improve the accuracy of the NIR spectroscopy analysis, including more samples from different cultivars and years. In the study to examine the possibility of using NIR spectroscopy to predict the chemical composition of compound ostrich feeds, the results indicated that NIR spectroscopy is a suitable tool for a rapid and reliable prediction of the crude protein, crude fibre, ether extract, IVOMD, ADF and NDF in compound ostrich feeds. Calibrations can be improved for amino acids if a larger sample pool is used to develop the calibrations. These studies indicated that NIR spectroscopy can be a rapid and successful tool for the prediction of the nutritive value up to certain amino acid contents of feedstuffs and compound ostrich feeds.
- Full Text:
- Date Issued: 2017
- Authors: Swart, Etheresia , Lehmann-Maritz, Maryna
- Date: 2017
- Subjects: Near infrared spectroscopy , Animal nutrition , Animal feeding
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/13779 , vital:27307
- Description: The chemical analysis of feed samples can be time consuming and expensive. The use of near infrared reflectance (NIR) spectroscopy was evaluated in a range of studies as a rapid technique to predict the chemical constituents in feedstuffs and compound ostrich feeds. The prediction of accurate results by NIR spectroscopy relies heavily upon obtaining a calibration set which represents the variation in the main population, accurate laboratory analyses and the application of the best mathematical procedures. This research project was designed to meet five objectives: The first objective was to determine the feasibility of using near infrared reflectance (NIR) spectroscopy to predict dry matter, ash, crude protein, crude fibre, oil content, and fatty acids such as palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1) and linoleic acid (C18:2) in sunflower seed meal. The second objective was to develop calibration models to predict the dry matter, crude protein and oil content in milled canola seed, compared to whole canola seeds. The third objective was to investigate the feasibility of using NIR spectroscopy to predict the dry matter, ash, crude protein, crude fibre and oil content in milled lupin seeds, compared to whole lupin seeds. The fourth objective was to describe the development of near infrared reflectance (NIR) spectroscopy calibration equations for the prediction of chemical composition and amino acid content from different populations of alfalfa hay (Medicago sativa L.). The last objective was to determine the potential of NIR spectroscopy to predict the dry matter, ash, crude protein, crude fibre, ether extract, acid detergent fibre (ADF), neutral detergent fibre (NDF), calcium, phosphorus, in vitro organic matter digestibility (IVOMD) and amino acids such as lysine, methionine, threonine and arginine in compound ostrich feed samples. The results of this study indicate that NIR spectroscopy calibrations in sunflower seed meal are only applicable in sunflower breeding programmes for a fast screening as it was not suitable for prediction purposes. Screening of sunflower seeds by NIR spectroscopy represents a rapid, simple and cost effective alternative that is a great utility for users who need to analyse a large number of samples. Calibrations developed for crude protein and oil content in milled canola seeds proved to be better than calibrations for whole canola seeds. Although the results indicated that calibrations were better for milled canola seeds, it indicated values that were typical of equations suitable for screening purposes to select samples for more detailed chemical analysis. According to calibration statistics obtained for crude protein, crude fibre and oil content in whole lupin seeds, there is no need to grind the seeds to scan the meal as similarly accurate results were obtained by analysing whole seeds. Screening of whole lupin seeds by NIR spectroscopy represents a rapid, simple and cost effective alternative that may be of great utility for users who need to analyse a large number of samples with no sample preparation. The calibration and validation statistics obtained in the study to test the potential of NIR spectroscopy to predict the chemical composition and amino acid contents in alfalfa hay, showed the accuracy was too low for routine analysis, although NIR spectroscopy could be used as a screening tool. Further research needs to be done to improve the accuracy of the NIR spectroscopy analysis, including more samples from different cultivars and years. In the study to examine the possibility of using NIR spectroscopy to predict the chemical composition of compound ostrich feeds, the results indicated that NIR spectroscopy is a suitable tool for a rapid and reliable prediction of the crude protein, crude fibre, ether extract, IVOMD, ADF and NDF in compound ostrich feeds. Calibrations can be improved for amino acids if a larger sample pool is used to develop the calibrations. These studies indicated that NIR spectroscopy can be a rapid and successful tool for the prediction of the nutritive value up to certain amino acid contents of feedstuffs and compound ostrich feeds.
- Full Text:
- Date Issued: 2017
Farmers’ perception on factors influencing small-scale vegetable production at Tsengiwe village, South Africa
- Authors: Gqibityala, Akhona
- Date: 2017
- Subjects: Farmers -- South Africa -- Eastern Cape Farms, Small -- South Africa -- Eastern Cape , Vegetable gardening -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/15281 , vital:28210
- Description: Food security and self-sufficiency in the rural areas has been and remains a major concern for the South African government. The study aimed to investigate farmer’s perception of factors influencing small-scale vegetable production in Tsengiwe village in the Eastern Cape. The research focus was on the following aspects that may have an influence on small-scale vegetable production: socio-economic factors, production and resource deficiencies and the impact of indigenous leafy vegetables. The researcher conducted several demonstration workshops during the field work. The pilot studies and community engagements were essential to extract knowledge systems embedded in the cultural traditions of indigenous or local communities. The action research was part of the reflective process of broadminded problem solving led by researcher and community. The research approach used a triangulation research method to extract information, whereby both quantitative and qualitative research was used to ensure greater accuracy. The main data collection was obtained from interviews with small-scale farming households in the Tsengiwe area. The study revealed that households were dependent on elderly female pensioners to source food and water. These women received most of their income from social grants and were mainly responsible for all farming activities in the households. Most households attempted to produce vegetables, although food security and self-sufficiency through own production was rarely achieved.Other perceived farming challenges included: lack of market accessibility, irrigation infrastructure, drought, financial limitations and soil degradation. Indigenous leafy vegetables were found to play a nutritional role in times of food shortage and not as much for their medicinal value. The study recommended the following interventions: Support for the elderly women in development and production practices, interventions to address factors affecting vegetable production, improving soil structure, working towards food self-sufficiency, moving away from dependence on mechanisation in rural farming.
- Full Text:
- Date Issued: 2017
- Authors: Gqibityala, Akhona
- Date: 2017
- Subjects: Farmers -- South Africa -- Eastern Cape Farms, Small -- South Africa -- Eastern Cape , Vegetable gardening -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/15281 , vital:28210
- Description: Food security and self-sufficiency in the rural areas has been and remains a major concern for the South African government. The study aimed to investigate farmer’s perception of factors influencing small-scale vegetable production in Tsengiwe village in the Eastern Cape. The research focus was on the following aspects that may have an influence on small-scale vegetable production: socio-economic factors, production and resource deficiencies and the impact of indigenous leafy vegetables. The researcher conducted several demonstration workshops during the field work. The pilot studies and community engagements were essential to extract knowledge systems embedded in the cultural traditions of indigenous or local communities. The action research was part of the reflective process of broadminded problem solving led by researcher and community. The research approach used a triangulation research method to extract information, whereby both quantitative and qualitative research was used to ensure greater accuracy. The main data collection was obtained from interviews with small-scale farming households in the Tsengiwe area. The study revealed that households were dependent on elderly female pensioners to source food and water. These women received most of their income from social grants and were mainly responsible for all farming activities in the households. Most households attempted to produce vegetables, although food security and self-sufficiency through own production was rarely achieved.Other perceived farming challenges included: lack of market accessibility, irrigation infrastructure, drought, financial limitations and soil degradation. Indigenous leafy vegetables were found to play a nutritional role in times of food shortage and not as much for their medicinal value. The study recommended the following interventions: Support for the elderly women in development and production practices, interventions to address factors affecting vegetable production, improving soil structure, working towards food self-sufficiency, moving away from dependence on mechanisation in rural farming.
- Full Text:
- Date Issued: 2017
Synthesis and characterisation of lanthanide complexes with O,O-donor ligands: towards a new generation of hydrophosphonylation catalysts
- Authors: Mkwakwi, Kwakhanya
- Date: 2017
- Subjects: Rare earth metals Catalysts
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/11986 , vital:27016
- Description: This study investigates the coordination behaviour of potentially bi- and tridentate O,O- and O,N,O-donor Schiff base ligands with trivalent lanthanide ions. The reactions of lanthanide nitrates with 2-((E)-(tert-butylimino)methyl)-6-methoxyphenol (HL1) have yielded five complexes that are described by the general formula [Ln(HL1)2(NO3)3] (Ln = Ce, Nd, Gd, Ho and Er) and were characterised using physico-chemical techniques including single-crystal X-ray diffraction spectroscopy. The cerium complex crystallised in a triclinic (P-1) space group, while the rest of the complexes crystallised in the monoclinic (P21/c) space group. All the complexes are ten-coordinate adopting a tetradecahedron geometry with two HL1 molecules coordinated through the phenolic and methoxy oxygen atoms. The coordination sphere is completed by six oxygen atoms from three bidentately coordinated nitrate ligands. Electronic data reveals that only the neodymium, holmium and erbium complexes exhibit weak f-f transitions in the visible region. The redox behaviour of the complexes was also investigated and reported. Five novel complexes were prepared by reacting 2-((E)-(tert-butylimino)methyl)phenol (HL2) with [Ln(NO3)3∙xH2O] (Ln = Gd and Dy ; x = 5 or 6) and [LnCl3∙6H2O] (Ln = Nd, Gd and Dy). The crystal structures of the former two complexes are isostructural and the coordination sphere is composed of three HL2 ligands bonded to the metal centre through the phenolic oxygen atom and three nitrate ions coordinated in a bidentate fashion. Both complexes are nine-coordinate and SHAPE analysis reveals that they adopted a muffin geometry. The average Ln-Onitrate and Ln-Ophenolate bond lengths are 2.5078 and 2.2814 Å, respectively. The complexes derived from the chloride salts exhibited an octahedral geometry with four monodentate ligands [Ln-Ophenolate distances range from 2.224(4) to 2.2797(17) Å] coordinating in the equatorial positions and two chloride ions [average Ln-Cl bond length is 2.6527 Å, and average Cl-Ln-Cl angles is 180o] in axial positions. The ligand coordinated through the phenolic oxygen with the phenolic proton migrating to the imino nitrogen to give a zwitterionic form of the ligand. There are weak C-H∙∙∙Cl interactions present and O-H∙∙∙N hydrogen bonds are also observed in the crystal packing. The synthesis of lanthanide complexes with methoxy-6-((E)-(phenylimino)methyl)phenol (HL3) was carried out in methanol to yield two mononuclear complexes with the formulae [Nd(HL3)2(NO3)3] and [Ho(HL3)(NO3)3(DMF)(H2O)]. Single-crystal crystallographic studies shows that the neodymium complex contains two HL3 ligands coordinated bidentately through its methoxide and phenolic oxygen atoms, with three nitrate ions also bonded to the metal in a bidentate manner. The coordination geometry in the holmium complex is composed of only oxygen atoms from the various ligands. Both complexes are ten-coordinate and exhibit a tetradecahedron geometry.
- Full Text:
- Date Issued: 2017
- Authors: Mkwakwi, Kwakhanya
- Date: 2017
- Subjects: Rare earth metals Catalysts
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/11986 , vital:27016
- Description: This study investigates the coordination behaviour of potentially bi- and tridentate O,O- and O,N,O-donor Schiff base ligands with trivalent lanthanide ions. The reactions of lanthanide nitrates with 2-((E)-(tert-butylimino)methyl)-6-methoxyphenol (HL1) have yielded five complexes that are described by the general formula [Ln(HL1)2(NO3)3] (Ln = Ce, Nd, Gd, Ho and Er) and were characterised using physico-chemical techniques including single-crystal X-ray diffraction spectroscopy. The cerium complex crystallised in a triclinic (P-1) space group, while the rest of the complexes crystallised in the monoclinic (P21/c) space group. All the complexes are ten-coordinate adopting a tetradecahedron geometry with two HL1 molecules coordinated through the phenolic and methoxy oxygen atoms. The coordination sphere is completed by six oxygen atoms from three bidentately coordinated nitrate ligands. Electronic data reveals that only the neodymium, holmium and erbium complexes exhibit weak f-f transitions in the visible region. The redox behaviour of the complexes was also investigated and reported. Five novel complexes were prepared by reacting 2-((E)-(tert-butylimino)methyl)phenol (HL2) with [Ln(NO3)3∙xH2O] (Ln = Gd and Dy ; x = 5 or 6) and [LnCl3∙6H2O] (Ln = Nd, Gd and Dy). The crystal structures of the former two complexes are isostructural and the coordination sphere is composed of three HL2 ligands bonded to the metal centre through the phenolic oxygen atom and three nitrate ions coordinated in a bidentate fashion. Both complexes are nine-coordinate and SHAPE analysis reveals that they adopted a muffin geometry. The average Ln-Onitrate and Ln-Ophenolate bond lengths are 2.5078 and 2.2814 Å, respectively. The complexes derived from the chloride salts exhibited an octahedral geometry with four monodentate ligands [Ln-Ophenolate distances range from 2.224(4) to 2.2797(17) Å] coordinating in the equatorial positions and two chloride ions [average Ln-Cl bond length is 2.6527 Å, and average Cl-Ln-Cl angles is 180o] in axial positions. The ligand coordinated through the phenolic oxygen with the phenolic proton migrating to the imino nitrogen to give a zwitterionic form of the ligand. There are weak C-H∙∙∙Cl interactions present and O-H∙∙∙N hydrogen bonds are also observed in the crystal packing. The synthesis of lanthanide complexes with methoxy-6-((E)-(phenylimino)methyl)phenol (HL3) was carried out in methanol to yield two mononuclear complexes with the formulae [Nd(HL3)2(NO3)3] and [Ho(HL3)(NO3)3(DMF)(H2O)]. Single-crystal crystallographic studies shows that the neodymium complex contains two HL3 ligands coordinated bidentately through its methoxide and phenolic oxygen atoms, with three nitrate ions also bonded to the metal in a bidentate manner. The coordination geometry in the holmium complex is composed of only oxygen atoms from the various ligands. Both complexes are ten-coordinate and exhibit a tetradecahedron geometry.
- Full Text:
- Date Issued: 2017
The investigation of chemical variation in the stems and rhizomes of cissampelos capensis l. f. (menispermaceae) the Eastern Cape medicinal plant
- Authors: Latolla, Nehemiah Solomon
- Date: 2017
- Subjects: Plants -- Composition Medicinal plants Endemic plants
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/13970 , vital:27362
- Description: Cissampelos capensis L. f. (Menispermaceae) commonly known as “Mayisake” (Xhosa) and “Dawidjieswortel” (Afrikaans) is the most commonly used medicinal plant of the Menispermaceae family in South Africa. The rhizomes of Cissampelos capensis are the most used part of the plant to treat illnesses. This poses a threat to the ongoing conservation of this valuable endemic species. Thus, we studied the chemical variation and subsequently the bioactivity in the stems and rhizomes of Cissampelos capensis, the Eastern Cape medicinal plant, to suggest the possible use of the stems for medicinal purposes. We studied the variation in the chemical composition in the stems and the rhizomes by employing four different extraction methods; the methanolic-, non-polar-, alkaloidal- and Total Tertiary Alkaloidal (TTA) to extract compounds from Cissampelos capensis. Employing various chromatographic techniques, HPLC, NMR and LC/MS to investigate the chemical variation and the in vitro assays for the crude materials of the stems and rhizomes of Cissampelos capensis. We successfully documented a library of the phytochemicals content in Cissampelos capensis from three different regions in the Eastern Cape. We could profile different extraction methods, with the TTA extraction delivering the best comparative profile. Employing LC/MS and HPLC we identified eleven known alkaloidal compounds in the stems and rhizomes. We also isolated a known alkaloid, pronuciferine, from the TTA extract and a crystal structure of proto-quericitol from the methanolic extract, which was isolated for the first time from Cissampelos capensis. Preliminary in vitro results suggested anti-inflammatory activity in the methanolic extracts of the stems and rhizomes, while the TTA extracts showed some cytotoxicity. Finally, through analytical HPLC analysis this study found as high as 31% similarity between the chemical variation of the stems and rhizomes, but key alkaloids were not always present, indicating more work is needed before the stems can be recommended as a replacement for the rhizomes.
- Full Text:
- Date Issued: 2017
- Authors: Latolla, Nehemiah Solomon
- Date: 2017
- Subjects: Plants -- Composition Medicinal plants Endemic plants
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/13970 , vital:27362
- Description: Cissampelos capensis L. f. (Menispermaceae) commonly known as “Mayisake” (Xhosa) and “Dawidjieswortel” (Afrikaans) is the most commonly used medicinal plant of the Menispermaceae family in South Africa. The rhizomes of Cissampelos capensis are the most used part of the plant to treat illnesses. This poses a threat to the ongoing conservation of this valuable endemic species. Thus, we studied the chemical variation and subsequently the bioactivity in the stems and rhizomes of Cissampelos capensis, the Eastern Cape medicinal plant, to suggest the possible use of the stems for medicinal purposes. We studied the variation in the chemical composition in the stems and the rhizomes by employing four different extraction methods; the methanolic-, non-polar-, alkaloidal- and Total Tertiary Alkaloidal (TTA) to extract compounds from Cissampelos capensis. Employing various chromatographic techniques, HPLC, NMR and LC/MS to investigate the chemical variation and the in vitro assays for the crude materials of the stems and rhizomes of Cissampelos capensis. We successfully documented a library of the phytochemicals content in Cissampelos capensis from three different regions in the Eastern Cape. We could profile different extraction methods, with the TTA extraction delivering the best comparative profile. Employing LC/MS and HPLC we identified eleven known alkaloidal compounds in the stems and rhizomes. We also isolated a known alkaloid, pronuciferine, from the TTA extract and a crystal structure of proto-quericitol from the methanolic extract, which was isolated for the first time from Cissampelos capensis. Preliminary in vitro results suggested anti-inflammatory activity in the methanolic extracts of the stems and rhizomes, while the TTA extracts showed some cytotoxicity. Finally, through analytical HPLC analysis this study found as high as 31% similarity between the chemical variation of the stems and rhizomes, but key alkaloids were not always present, indicating more work is needed before the stems can be recommended as a replacement for the rhizomes.
- Full Text:
- Date Issued: 2017
A study of lanthanide complexes with di-2-pyridyl ligands
- Authors: Coetzee, Louis-Charl Cloete
- Date: 2016
- Subjects: Rare earth metals
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/4731 , vital:20659
- Description: The ligands di(2-pyridyl) ketone (DPK) and cis-1,2 di(2-pyridyl) ethylene (DPE) are N,N,Odonor ligands that can undergo nucleophilic addition and become more flexible for coordination. The reaction between the lanthanide thiocyanate salt and DPK gave rise to seven novel complexes of the general formula [Ln(NCS)3(DPKOH)3], where Ln = La, Ce, Nd, Eu, Tb, Dy and Ho. 1H NMR spectroscopy verified that the ligand underwent nucleophilic addition upon coordination. This was further confirmed using UV-Vis spectroscopy which showed a shift in the absorption bands due to conjugation of electrons within the pyridyl ring upon coordination. UV-Vis spectroscopy was also utilised to test the covalent character of the neodymium and holmium complexes. X-ray diffraction and IR spectroscopy showed that three DPK ligands coordinated bidentately through a pyridinic nitrogen and a hydroxyl oxygen, while three isothiocyanato molecules completed the coordination environment around each metal. Furthermore, X-ray diffraction also revealed that these complexes are isostructural, ninecoordinate and the polyhedron which encloses each ion is of trigonal tricapped prismatic shape with D3h symmetry. Micro-analysis on all the complexes, except lanthanum and holmium confirmed the molecular formulae produced from the crystallographic data of each complex. The reaction between the lanthanide thiocyanate salt and DPE produced poor quality crystals which could not be detected by X-ray diffraction. The lanthanide salts used for this reaction were lanthanum, neodymium, europium, dysprosium and holmium. Upon coordination, conductivity measurements detected the presence of lanthanide ions in each solution. 1H NMR and IR spectroscopic studies showed that the ethylenic moiety of DPE underwent nucleophilic addition upon coordination. UV-Vis spectroscopy further confirmed nucleophilic addition upon coordination due to shifts in absorption bands. IR spectroscopy verified the possibility of a bidentate coordination to each metal through a pyridinic nitrogen and a hydroxyl oxygen as well as a monodentate coordination through isothiocyanato ligands. A micro-analysis on all the complexes provided the molecular formulae that can best fit each complex. The effect of the solvent molecules on the bonding parameters of the lanthanum complex was investigated. An analysis of the results produced from crystallographic data revealed the presence of intermolecular forces which interacted and stabilised the complex.
- Full Text:
- Date Issued: 2016
- Authors: Coetzee, Louis-Charl Cloete
- Date: 2016
- Subjects: Rare earth metals
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/4731 , vital:20659
- Description: The ligands di(2-pyridyl) ketone (DPK) and cis-1,2 di(2-pyridyl) ethylene (DPE) are N,N,Odonor ligands that can undergo nucleophilic addition and become more flexible for coordination. The reaction between the lanthanide thiocyanate salt and DPK gave rise to seven novel complexes of the general formula [Ln(NCS)3(DPKOH)3], where Ln = La, Ce, Nd, Eu, Tb, Dy and Ho. 1H NMR spectroscopy verified that the ligand underwent nucleophilic addition upon coordination. This was further confirmed using UV-Vis spectroscopy which showed a shift in the absorption bands due to conjugation of electrons within the pyridyl ring upon coordination. UV-Vis spectroscopy was also utilised to test the covalent character of the neodymium and holmium complexes. X-ray diffraction and IR spectroscopy showed that three DPK ligands coordinated bidentately through a pyridinic nitrogen and a hydroxyl oxygen, while three isothiocyanato molecules completed the coordination environment around each metal. Furthermore, X-ray diffraction also revealed that these complexes are isostructural, ninecoordinate and the polyhedron which encloses each ion is of trigonal tricapped prismatic shape with D3h symmetry. Micro-analysis on all the complexes, except lanthanum and holmium confirmed the molecular formulae produced from the crystallographic data of each complex. The reaction between the lanthanide thiocyanate salt and DPE produced poor quality crystals which could not be detected by X-ray diffraction. The lanthanide salts used for this reaction were lanthanum, neodymium, europium, dysprosium and holmium. Upon coordination, conductivity measurements detected the presence of lanthanide ions in each solution. 1H NMR and IR spectroscopic studies showed that the ethylenic moiety of DPE underwent nucleophilic addition upon coordination. UV-Vis spectroscopy further confirmed nucleophilic addition upon coordination due to shifts in absorption bands. IR spectroscopy verified the possibility of a bidentate coordination to each metal through a pyridinic nitrogen and a hydroxyl oxygen as well as a monodentate coordination through isothiocyanato ligands. A micro-analysis on all the complexes provided the molecular formulae that can best fit each complex. The effect of the solvent molecules on the bonding parameters of the lanthanum complex was investigated. An analysis of the results produced from crystallographic data revealed the presence of intermolecular forces which interacted and stabilised the complex.
- Full Text:
- Date Issued: 2016
Absorptive capacity for responding to environmental: change an assessment of three public-sector agencies
- Authors: Mc Culloch, Samantha
- Date: 2016
- Subjects: Global environmental change Absorptive capacity (Economics)
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/11762 , vital:26966
- Description: In a time of global environmental instability, public-sector organisations that manage and protect natural resources, which are needed for human wellbeing, play an increasingly important role. These organisations frequently have to weigh up the costs and benefits of managing natural resources and their services for the public good. Management of social-ecological systems is commonly characterised by uncertainty, disagreement and trade-offs. In South Africa, these challenges are compounded by the fact that mandated organisations are often inadequately resourced in terms of finances, skilled staff and infrastructure. In order to maintain the resilience and robustness of social-ecological systems, public-sector organisations need to cultivate a set of dynamic capabilities, with strong emphasis on learning from their experiences and adapting their management strategies, to innovate and improve their performances. Absorptive capacity (AC) has been described as the ability of an organisation to recognise the value of new external information, acquire it and assimilate it within the organisation, transforming it by applying it with existing knowledge and exploiting the new knowledge for benefit. Organisations with good AC are able to recognise rapidly changing environments and address them by renewing and building on their levels of skill, knowledge and capability to deal with change. This construct has been extensively researched in industries related to business and technology, where its development has been found to stimulate innovative capabilities. There has, however, been little research into its relevance for public-sector organisations or organisations with environmental mandates. This study used methodological triangulation to assess the perceptions of employees on the current state of AC in three public-sector organisations with environmental mandates. This was done to gain insight into their capacity to absorb information and apply their new knowledge in decision-making, in a manner that navigates through environmental change. The key findings of this research suggest that knowledge transformation and exploitation are enhanced by in-house research capabilities and cross-functional interface between internal departments. These findings also suggest that the acquisition of knowledge is not only determined by the in-house research capacity but also depends on the resources available to these departments in terms of time, finances and skilled staff. There was minimal evidence of knowledge exploitation; however, obstacles that were highlighted as hindering this process included individual responsibility and motivation, as well as general organisation capacities, such as communication hierarchies, funding, time and organisational silos. This research found that the well-studied concept of AC can be used as an institutional mechanism to assess and promote adaptive capacity in public-sector organisations with environmental mandates to navigate and innovate through the Anthropocene.
- Full Text:
- Date Issued: 2016
- Authors: Mc Culloch, Samantha
- Date: 2016
- Subjects: Global environmental change Absorptive capacity (Economics)
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/11762 , vital:26966
- Description: In a time of global environmental instability, public-sector organisations that manage and protect natural resources, which are needed for human wellbeing, play an increasingly important role. These organisations frequently have to weigh up the costs and benefits of managing natural resources and their services for the public good. Management of social-ecological systems is commonly characterised by uncertainty, disagreement and trade-offs. In South Africa, these challenges are compounded by the fact that mandated organisations are often inadequately resourced in terms of finances, skilled staff and infrastructure. In order to maintain the resilience and robustness of social-ecological systems, public-sector organisations need to cultivate a set of dynamic capabilities, with strong emphasis on learning from their experiences and adapting their management strategies, to innovate and improve their performances. Absorptive capacity (AC) has been described as the ability of an organisation to recognise the value of new external information, acquire it and assimilate it within the organisation, transforming it by applying it with existing knowledge and exploiting the new knowledge for benefit. Organisations with good AC are able to recognise rapidly changing environments and address them by renewing and building on their levels of skill, knowledge and capability to deal with change. This construct has been extensively researched in industries related to business and technology, where its development has been found to stimulate innovative capabilities. There has, however, been little research into its relevance for public-sector organisations or organisations with environmental mandates. This study used methodological triangulation to assess the perceptions of employees on the current state of AC in three public-sector organisations with environmental mandates. This was done to gain insight into their capacity to absorb information and apply their new knowledge in decision-making, in a manner that navigates through environmental change. The key findings of this research suggest that knowledge transformation and exploitation are enhanced by in-house research capabilities and cross-functional interface between internal departments. These findings also suggest that the acquisition of knowledge is not only determined by the in-house research capacity but also depends on the resources available to these departments in terms of time, finances and skilled staff. There was minimal evidence of knowledge exploitation; however, obstacles that were highlighted as hindering this process included individual responsibility and motivation, as well as general organisation capacities, such as communication hierarchies, funding, time and organisational silos. This research found that the well-studied concept of AC can be used as an institutional mechanism to assess and promote adaptive capacity in public-sector organisations with environmental mandates to navigate and innovate through the Anthropocene.
- Full Text:
- Date Issued: 2016
Factors that influence the sustainability of rural crop production community projects in the Umzimvubu District
- Authors: Majiki, Fezeka
- Date: 2016
- Subjects: Sustainable agriculture -- South Africa -- Eastern Cape , Economic development projects -- South Africa -- Eastern Cape , Rural development -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/8089 , vital:24991
- Description: Maize production is the main cropping activity in the Umzimvubu district. This cereal crop is the staple food for the Eastern Cape’s rural communities and accounts for nearly 95 per cent of the crops cultivated in dry-land cropping programmes. Food security in rural areas has been a major concern for the South African government. In attempts to mitigate hunger and poverty, the government has initiated rural development maize production projects. The primary objectives of the projects were to achieve sustainable livelihoods and rural development for the poor. The projects were expected to improve the quality of rural life and provide basic nutritional requirements of the community. Historically the rural poor have had to fend for themselves through subsistence farming in adverse environments. Input costs for farming have become increasingly expensive; this resulted in major challenges for subsistence farming. The crop production projects initiated in the Umzimvubu district have not been sustainable and have fallen short of addressing the needs of the various communities. The study aims to identify the factors that influence the sustainability of the crop production projects in the Umzimvubu district. A triangulation research method was used to provide multiple viewpoints to examine the data; this allows for greater accuracy of the research. The mixed method approach in which the researcher collects and analyses data integrates the findings and draws inferences using both qualitative and quantitative methodology. The quantitative research methodology provided the demographics and biographical data on the participants. The qualitative research methodology concentrated on the focus group discussions that gave an insight into the participants' views, perceptions and concerns. Focus groups were used to examine the factors influencing the sustain-ability of the projects and to explore how these projects are perceived and under-stood by the community and people working on the projects. The research interest is not only in what the project beneficiaries think, but also in why they think as they do. The main data collection was obtained from the focus groups and individual face-to-face interviews with the beneficiaries of the crop projects in the Umzimvubu district. It was found that the farming areas required rehabilitation, were susceptible to erosion and degradation, and lacked adequate land use practices. The beneficiaries of the cropping programmes had small amounts of other crops growing in their individual household gardens for household use in conjunction with the maize received from the maize programmes. The income made from selling maize from the programmes was insignificant and did not contribute substantially to the household needs, as the communities in these projects were still failing to secure adequate food requirements. The maize yields do not substantiate the monetary investment from the beneficiaries. Furthermore, the findings indicated that the beneficiaries do not receive consistent income from the programmes. The participants consisted of large households comprising mainly elderly people who depended on social grants as a regular source of income. These elderly were burdened with taking care of their grandchildren, whose parents were employed in either urban areas or unemployed and formed part of the household. The unemployed young adults also depended on child support grants for income. The maize harvested had to be shared between a large number of community members and the livestock. The findings also suggested that there was dependency on outside contractors for cultivation and other practices. The study found that most of the beneficiaries felt disempowered, as they had not been involved in the decision-making process. Furthermore, policy-makers failed to acknowledge existing indigenous knowledge and practices of the rural communities (i.e. inter-cropping and green mealie harvesting). Indigenous practices should be included into the programmes instead of compelling beneficiaries to adhere to new forms of cultivation. The communities introduction to new large-scale and challenging, highly technological methods resulted in most of the communities being fully dependent on government support and guidance. Training and the empowerment of beneficiaries are imperative. Rural people should be included in development of strategies and the role of the women should be given more recognition. It should be acknowledged that rural households are diverse and that the model cannot apply to each village or community.
- Full Text:
- Date Issued: 2016
- Authors: Majiki, Fezeka
- Date: 2016
- Subjects: Sustainable agriculture -- South Africa -- Eastern Cape , Economic development projects -- South Africa -- Eastern Cape , Rural development -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/8089 , vital:24991
- Description: Maize production is the main cropping activity in the Umzimvubu district. This cereal crop is the staple food for the Eastern Cape’s rural communities and accounts for nearly 95 per cent of the crops cultivated in dry-land cropping programmes. Food security in rural areas has been a major concern for the South African government. In attempts to mitigate hunger and poverty, the government has initiated rural development maize production projects. The primary objectives of the projects were to achieve sustainable livelihoods and rural development for the poor. The projects were expected to improve the quality of rural life and provide basic nutritional requirements of the community. Historically the rural poor have had to fend for themselves through subsistence farming in adverse environments. Input costs for farming have become increasingly expensive; this resulted in major challenges for subsistence farming. The crop production projects initiated in the Umzimvubu district have not been sustainable and have fallen short of addressing the needs of the various communities. The study aims to identify the factors that influence the sustainability of the crop production projects in the Umzimvubu district. A triangulation research method was used to provide multiple viewpoints to examine the data; this allows for greater accuracy of the research. The mixed method approach in which the researcher collects and analyses data integrates the findings and draws inferences using both qualitative and quantitative methodology. The quantitative research methodology provided the demographics and biographical data on the participants. The qualitative research methodology concentrated on the focus group discussions that gave an insight into the participants' views, perceptions and concerns. Focus groups were used to examine the factors influencing the sustain-ability of the projects and to explore how these projects are perceived and under-stood by the community and people working on the projects. The research interest is not only in what the project beneficiaries think, but also in why they think as they do. The main data collection was obtained from the focus groups and individual face-to-face interviews with the beneficiaries of the crop projects in the Umzimvubu district. It was found that the farming areas required rehabilitation, were susceptible to erosion and degradation, and lacked adequate land use practices. The beneficiaries of the cropping programmes had small amounts of other crops growing in their individual household gardens for household use in conjunction with the maize received from the maize programmes. The income made from selling maize from the programmes was insignificant and did not contribute substantially to the household needs, as the communities in these projects were still failing to secure adequate food requirements. The maize yields do not substantiate the monetary investment from the beneficiaries. Furthermore, the findings indicated that the beneficiaries do not receive consistent income from the programmes. The participants consisted of large households comprising mainly elderly people who depended on social grants as a regular source of income. These elderly were burdened with taking care of their grandchildren, whose parents were employed in either urban areas or unemployed and formed part of the household. The unemployed young adults also depended on child support grants for income. The maize harvested had to be shared between a large number of community members and the livestock. The findings also suggested that there was dependency on outside contractors for cultivation and other practices. The study found that most of the beneficiaries felt disempowered, as they had not been involved in the decision-making process. Furthermore, policy-makers failed to acknowledge existing indigenous knowledge and practices of the rural communities (i.e. inter-cropping and green mealie harvesting). Indigenous practices should be included into the programmes instead of compelling beneficiaries to adhere to new forms of cultivation. The communities introduction to new large-scale and challenging, highly technological methods resulted in most of the communities being fully dependent on government support and guidance. Training and the empowerment of beneficiaries are imperative. Rural people should be included in development of strategies and the role of the women should be given more recognition. It should be acknowledged that rural households are diverse and that the model cannot apply to each village or community.
- Full Text:
- Date Issued: 2016
Investigating the effectiveness of microcatchments at enhancing transplant performance in Nama-Karoo riparian ecosystem restoration
- Jackson, Andrew St. John, Wigley, Benjamin, Schumann, Bonnie, Currie, Bianca
- Authors: Jackson, Andrew St. John , Wigley, Benjamin , Schumann, Bonnie , Currie, Bianca
- Date: 2016
- Subjects: Arid regions agriculture , Environmental degradation , Range ecology
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/7469 , vital:21782
- Description: Globally agricultural rangelands have been subjected to degradation through over-utilization. The loss of productivity of agricultural rangelands around the world has led to the development of methods to restore the productivity of these areas. In South Africa, extensive areas of the Nama-Karoo have been degraded or transformed due in part to unsustainable agricultural activities. The development of restoration methods which are easily implementable and financially viable could increase the probability of stakeholders implementing restoration activities on privately owned land. The removal of the degrading factor is not sufficient to reverse the degradative trend in dryland environments. Active measures must be implemented to arrest the degradation cascade. The climatic conditions of the rangelands of South Africa are limiting to plant performance and the favourable conditions are sporadic. The translocation of plants should be combined with the amelioration of the local conditions. This study tested the restoration technique of microcatchments in association with plant translocation. The effects of microcatchments and planting combinations which were best suited to the survival and performance of the transplants were determined through a field trail. The results showed that microcatchments created microsites which were conducive to transplant survival and growth, including nutrient accumulation and increased soil moisture. The success of the method was dependent on the planting combination used. Plants which are adapted to inundation and the saline conditions of the site performed better. Plants which were older at the time of translocation had higher survival rates than younger transplants. In the conditions of this site, planting adjacent to the microcatchments was necessary to avoid inundation induced mortalities. The environmental conditions of the Nama-Karoo necessitate the coordination of restoration activities with the predicted favourable conditions in order to improve the success of restoration activities.
- Full Text:
- Date Issued: 2016
- Authors: Jackson, Andrew St. John , Wigley, Benjamin , Schumann, Bonnie , Currie, Bianca
- Date: 2016
- Subjects: Arid regions agriculture , Environmental degradation , Range ecology
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/7469 , vital:21782
- Description: Globally agricultural rangelands have been subjected to degradation through over-utilization. The loss of productivity of agricultural rangelands around the world has led to the development of methods to restore the productivity of these areas. In South Africa, extensive areas of the Nama-Karoo have been degraded or transformed due in part to unsustainable agricultural activities. The development of restoration methods which are easily implementable and financially viable could increase the probability of stakeholders implementing restoration activities on privately owned land. The removal of the degrading factor is not sufficient to reverse the degradative trend in dryland environments. Active measures must be implemented to arrest the degradation cascade. The climatic conditions of the rangelands of South Africa are limiting to plant performance and the favourable conditions are sporadic. The translocation of plants should be combined with the amelioration of the local conditions. This study tested the restoration technique of microcatchments in association with plant translocation. The effects of microcatchments and planting combinations which were best suited to the survival and performance of the transplants were determined through a field trail. The results showed that microcatchments created microsites which were conducive to transplant survival and growth, including nutrient accumulation and increased soil moisture. The success of the method was dependent on the planting combination used. Plants which are adapted to inundation and the saline conditions of the site performed better. Plants which were older at the time of translocation had higher survival rates than younger transplants. In the conditions of this site, planting adjacent to the microcatchments was necessary to avoid inundation induced mortalities. The environmental conditions of the Nama-Karoo necessitate the coordination of restoration activities with the predicted favourable conditions in order to improve the success of restoration activities.
- Full Text:
- Date Issued: 2016
Investigating the effects of mopane worms (Imbrasia belina) on nutrients, Venetia-Limpopo Nature Reserve, South Africa
- De Swardt, Donovan Barry, O’Connor, Tim
- Authors: De Swardt, Donovan Barry , O’Connor, Tim
- Date: 2016
- Subjects: Herbivores -- Ecology -- South Africa -- Limpopo , Phytophagous insects -- South Africa -- Limpopo , Mopane worm -- South Africa -- Limpopo , Soil fertility -- South Africa -- Limpopo
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/9273 , vital:26558
- Description: Ecologists have long been aware that large mammalian herbivores can alter ecosystem functioning in various ways, for example through changing where they defecate and urinate, which consequently affects nutrient cycling. The effects of herbivorous insects on ecosystems, however, have received limited attention until recently. Insects are capable of mass outbreaks, they can consume large volumes of vegetative material and can deposit large quantities of dung (frass), one example being the mopane worm, Imbrasia belina. This study looked at the effect of mopane worm frass on soil fertility in the mopane veld of the Venetia-Limpopo Nature Reserve and neighbouring Haakdoring farm. It found that mopane worms are capable of altering soil nutrient dynamics beneath the trees where they are browsing in three ways. Firstly, they increase the potential amount of nutrients deposited when compared with that deposited through conventional leaf litter. Secondly, they alter the rate of nutrient recycling by depositing nutrients in frass which decomposes more rapidly than conventional leaf litter. Lastly, they increase the amounts of potassium and phosphorus in the soil. While there is no conclusive data from this study that the mopane veld would become extinct if mopane worms were harvested to extinction, it has shown that there is relatively little evidence on how herbivorous insects could affect ecosystem functioning in the landscapes in which they occur. Further research is recommended that investigates how mopane worms influence soil fertility in more detail and over multiple geographical locations.
- Full Text:
- Date Issued: 2016
- Authors: De Swardt, Donovan Barry , O’Connor, Tim
- Date: 2016
- Subjects: Herbivores -- Ecology -- South Africa -- Limpopo , Phytophagous insects -- South Africa -- Limpopo , Mopane worm -- South Africa -- Limpopo , Soil fertility -- South Africa -- Limpopo
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/9273 , vital:26558
- Description: Ecologists have long been aware that large mammalian herbivores can alter ecosystem functioning in various ways, for example through changing where they defecate and urinate, which consequently affects nutrient cycling. The effects of herbivorous insects on ecosystems, however, have received limited attention until recently. Insects are capable of mass outbreaks, they can consume large volumes of vegetative material and can deposit large quantities of dung (frass), one example being the mopane worm, Imbrasia belina. This study looked at the effect of mopane worm frass on soil fertility in the mopane veld of the Venetia-Limpopo Nature Reserve and neighbouring Haakdoring farm. It found that mopane worms are capable of altering soil nutrient dynamics beneath the trees where they are browsing in three ways. Firstly, they increase the potential amount of nutrients deposited when compared with that deposited through conventional leaf litter. Secondly, they alter the rate of nutrient recycling by depositing nutrients in frass which decomposes more rapidly than conventional leaf litter. Lastly, they increase the amounts of potassium and phosphorus in the soil. While there is no conclusive data from this study that the mopane veld would become extinct if mopane worms were harvested to extinction, it has shown that there is relatively little evidence on how herbivorous insects could affect ecosystem functioning in the landscapes in which they occur. Further research is recommended that investigates how mopane worms influence soil fertility in more detail and over multiple geographical locations.
- Full Text:
- Date Issued: 2016
Optimisation of clearcoat viscosity
- Authors: Bukula, Nwabisa Asanda
- Date: 2016
- Subjects: Coating processes , Automobiles -- Bodies -- Maintenance and repair
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/4814 , vital:20707
- Description: Modern automobiles are painted with basecoat, technology which is either metallic, solid colour or pearlescent. This requires protection from chemicals, scratching, weathering and UV light by applying a protective top coat (clearcoat) over the basecoat. For the clearcoat to cure into a hard protective shell it undergoes an irreversible crosslinking process. This usually takes place over the first four to five hours, depending on the formulation and weather conditions. The speed of crosslinking can be enhanced by temperature. Pot life is important as it can affect the overall quality of the painted surface. If crosslinking occurs too quickly, before the clearcoat is applied onto the surface, the clearcoat cannot be used to produce a good quality finish. The “expired” mixture is thus discarded. If used, the quality of the finished product cannot be guaranteed to last, and the paintwork may have to be redone. This often means removing the underlying paint and primer as well with the clearcoat film. Besides the time lost, the discarded clearcoat mixture often lands in the landfill, polluting ground water and the environment. It is thus important from the point of view of both the environment preservation and waste management, that as much clearcoat as possible is used without being wasted. It was proven in an earlier study (BSc Hon Formulation Science Treatise, 2011) that adding eugenol to a clearcoat mixture after crosslinking had started could reduce its viscosity, which is an indicator of crosslinking progress. Crosslinking subsequently resumed at a lower rate than in traditional blends. If stored away from oxygen and high temperatures, this blend could maintain optimum viscosity indefinitely. In this follow up study an optimum formulation was developed using D - optimal experimental design. It sought to extend the pot life to avoid waste to spray painters while saving the environment from pollution. The formulation that gave the desired viscosity after five hours of pot life was adopted. It was hypothesised that the optimum formulated clearcoat mixture would have a longer pot life than its traditional counterparts, and that it would perform just as well as the traditional clearcoat mixtures. To study the rate of crosslinking (disappearance of functional groups and appearance of the urethane bond), FTIR spectrometry was performed on a mixture produced from the optimized formula in comparison to that of a traditional mixture (the control). The rate of disappearance of functional groups was found to be lower in the eugenol mixture than in the control mixture. After six hours, eugenol was added into the control mixture, and this seemed to reduce the viscosity with the re-emergence of functional groups in the mixture. After 24 hours of crosslinking, an FTIR scan was done on the solid sample and this revealed that the eugenol mixture had crosslinked fully, with no detectable functional groups in the sample.
- Full Text:
- Date Issued: 2016
- Authors: Bukula, Nwabisa Asanda
- Date: 2016
- Subjects: Coating processes , Automobiles -- Bodies -- Maintenance and repair
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/4814 , vital:20707
- Description: Modern automobiles are painted with basecoat, technology which is either metallic, solid colour or pearlescent. This requires protection from chemicals, scratching, weathering and UV light by applying a protective top coat (clearcoat) over the basecoat. For the clearcoat to cure into a hard protective shell it undergoes an irreversible crosslinking process. This usually takes place over the first four to five hours, depending on the formulation and weather conditions. The speed of crosslinking can be enhanced by temperature. Pot life is important as it can affect the overall quality of the painted surface. If crosslinking occurs too quickly, before the clearcoat is applied onto the surface, the clearcoat cannot be used to produce a good quality finish. The “expired” mixture is thus discarded. If used, the quality of the finished product cannot be guaranteed to last, and the paintwork may have to be redone. This often means removing the underlying paint and primer as well with the clearcoat film. Besides the time lost, the discarded clearcoat mixture often lands in the landfill, polluting ground water and the environment. It is thus important from the point of view of both the environment preservation and waste management, that as much clearcoat as possible is used without being wasted. It was proven in an earlier study (BSc Hon Formulation Science Treatise, 2011) that adding eugenol to a clearcoat mixture after crosslinking had started could reduce its viscosity, which is an indicator of crosslinking progress. Crosslinking subsequently resumed at a lower rate than in traditional blends. If stored away from oxygen and high temperatures, this blend could maintain optimum viscosity indefinitely. In this follow up study an optimum formulation was developed using D - optimal experimental design. It sought to extend the pot life to avoid waste to spray painters while saving the environment from pollution. The formulation that gave the desired viscosity after five hours of pot life was adopted. It was hypothesised that the optimum formulated clearcoat mixture would have a longer pot life than its traditional counterparts, and that it would perform just as well as the traditional clearcoat mixtures. To study the rate of crosslinking (disappearance of functional groups and appearance of the urethane bond), FTIR spectrometry was performed on a mixture produced from the optimized formula in comparison to that of a traditional mixture (the control). The rate of disappearance of functional groups was found to be lower in the eugenol mixture than in the control mixture. After six hours, eugenol was added into the control mixture, and this seemed to reduce the viscosity with the re-emergence of functional groups in the mixture. After 24 hours of crosslinking, an FTIR scan was done on the solid sample and this revealed that the eugenol mixture had crosslinked fully, with no detectable functional groups in the sample.
- Full Text:
- Date Issued: 2016
Perceptions and practices of small-scale piggery farmers towards animal welfare in the Nelson Mandela Bay Metropole
- Authors: Maqhajana, Mzwanele
- Date: 2016
- Subjects: Animal welfare -- South Africa -- Nelson Mandela Bay Municipality , Farms, Small -- South Africa -- Nelson Mandela Bay Municipality
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/8079 , vital:24719
- Description: There has been an increasing concern about animal welfare in small-scale farming as the farmers' agricultural practices shift towards intensive agriculture. It has become important to comprehend how small-scale farmers perceive and practice animal welfare relative to production and market integration. To solve the research problem, the research emphasis was on assessing the following practices; procedures adopted by the small-scale farmers, welfare levels verses industry equirements for market integration; determinants affecting small-scale perceptions and attitudes towards animal welfare and how has animal welfare affected farm development and production. The research focus for this study was to investigate the linkage between perceptions and this process. In order to achieve a more in-depth understanding of the study while also ensuring its validity and correctness a triangulation research method was applied, which consisted of a quantitative and qualitative method approach. The focus groups and structured research interview questions were used as the main data collections instruments. The study consisted of sixty-two piggery small-scale farmers from three areas of the Nelson Mandela Bay metropole. The study found that there was a disparity between the perceptions and practice of small-scale farmers. Farmers perceived their practices as acceptable. However, on most of the farms the pigs were farmed in an unhygienic environment, had limited handling facilities, the farmers had unconventional methods to handle the pigs; there was poor support from technical services, many of the farmers never administered animal welfare evaluations and applied questionable feeding practices. The study also indicated that less than 15% had suitable facilities to accommodate suitable reproduction and piglet care. The researcher recommended the following interventions to improve animal welfare approaches with small-scale farmers in the Nelson Mandela Bay metropole: Training and information campaigns to improve small-scale piggery farmers' perception and knowledge of animal welfare, as well as market standards and requirements. Strengthening the relationship between the small-scale piggery farmers and animal welfare stakeholders. Including active engagement between small scale piggery farmers and the Department of Rural Development, Agrarian Reform and Urban Agriculture Unit of the Nelson Mandela Bay Municipality. Encouraging farmers to strive for stronger markets to facilitate better income and care of animals.
- Full Text:
- Date Issued: 2016
- Authors: Maqhajana, Mzwanele
- Date: 2016
- Subjects: Animal welfare -- South Africa -- Nelson Mandela Bay Municipality , Farms, Small -- South Africa -- Nelson Mandela Bay Municipality
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/8079 , vital:24719
- Description: There has been an increasing concern about animal welfare in small-scale farming as the farmers' agricultural practices shift towards intensive agriculture. It has become important to comprehend how small-scale farmers perceive and practice animal welfare relative to production and market integration. To solve the research problem, the research emphasis was on assessing the following practices; procedures adopted by the small-scale farmers, welfare levels verses industry equirements for market integration; determinants affecting small-scale perceptions and attitudes towards animal welfare and how has animal welfare affected farm development and production. The research focus for this study was to investigate the linkage between perceptions and this process. In order to achieve a more in-depth understanding of the study while also ensuring its validity and correctness a triangulation research method was applied, which consisted of a quantitative and qualitative method approach. The focus groups and structured research interview questions were used as the main data collections instruments. The study consisted of sixty-two piggery small-scale farmers from three areas of the Nelson Mandela Bay metropole. The study found that there was a disparity between the perceptions and practice of small-scale farmers. Farmers perceived their practices as acceptable. However, on most of the farms the pigs were farmed in an unhygienic environment, had limited handling facilities, the farmers had unconventional methods to handle the pigs; there was poor support from technical services, many of the farmers never administered animal welfare evaluations and applied questionable feeding practices. The study also indicated that less than 15% had suitable facilities to accommodate suitable reproduction and piglet care. The researcher recommended the following interventions to improve animal welfare approaches with small-scale farmers in the Nelson Mandela Bay metropole: Training and information campaigns to improve small-scale piggery farmers' perception and knowledge of animal welfare, as well as market standards and requirements. Strengthening the relationship between the small-scale piggery farmers and animal welfare stakeholders. Including active engagement between small scale piggery farmers and the Department of Rural Development, Agrarian Reform and Urban Agriculture Unit of the Nelson Mandela Bay Municipality. Encouraging farmers to strive for stronger markets to facilitate better income and care of animals.
- Full Text:
- Date Issued: 2016