Evaluating farmers' perceptions and the impact of bush encroachment on herbaceous vegetation and soil nutrients in Sheshegu communal rangelands of the Eastern Cape, South Africa
- Authors: Tokozwayo, Sive
- Date: 2016
- Subjects: Range management -- South Africa -- Eastern Cape Brush -- Control -- South Africa -- Eastern Cape Communal rangelands -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/2733 , vital:28066
- Description: Communal rangelands occupy 13 percent of the agricultural land in South Africa, and these rangelands serve as a source of feed to livestock. These areas are threatened by bush encroachment due to poor rangeland management. This study was conducted in Alice (Sheshegu communal area) and the objective was to assess farmers' perceptions and the impact of bush encroachment on herbaceous vegetation and soil nutrients. Structured questionnaires were used to assess indigenous knowledge of communal farmers on the impact of bush encroachment on rangelands. Fourty (40) respondents from households who owned livestock were randomly selected and interviewed at Sheshegu village. About 89 percent of communal farmers perceived that change of their grasslands to encroached savannas was caused by unreliable rainfall, prolonged drought, and poor rangeland management. Rangeland assessment was performed at four sites (Scattered, Moderate, Mixed and Dense bushland. 100mx50m were demarcated per site, and four 100m transects were laid parallel to each other, 30m apart. The step point method was used to determine both species composition and basal cover. Biomass production was determined by harvesting forage within randomly-paced a 0.25m2 quadrats. Aristada congesta and Eragrostis obtuse were the most dominating grass species in dense, mixed and moderate bushland. Scattered bushland was dominated by Themeda triandra. Biomass production increases with increase in bush density and basal cover improved from winter to summer season. Increaser grass species increase with the increase in bush density, this indicated that the rangeland was poorly managed and palatable species were being replaced by less palatable ones. Species composition of woody plants was determined within a 200m2 belt transect in all sites. Maytenus polycantha, Aloe ferox, Erehia rigida and lucas capensis were the most dominant woody species in Mixed bushland while Acacia karroo was most dominated in Scattered, Moderate and Dense bushland. Woody density showed no significant differences (P> 0.05) between Dense, Mixed and Moderate bushland. Woody plant density in all these sites exceed 2500 plants/ha, which showed that the rangeland was encroached with woody plants. Soil nutrient content was determined for each site. Five samples of soil were collected per site to test the effect of bush encroachment on soil nutrient composition. The concentration of nitrogen and soil pH increased with increase in bush density, while that of potassium, phosphorous, magnesium, sodium and sulphur showed no significant differences (P>0.05) across all homogenous vegetation units. The study revealed that Sheshegu communal farmers are aware of both negative and positive effects of encroachment on their community, and also argue that the government is not willing to support communal farmers in the process of reducing the spread of bush encroachment. It was concluded that the concentration of nitrogen and soil pH increased with increasing bush density and that bush encroachment had negative effects on herbaceous species. It was recommended that communal farmers should be formulating rangeland rules and regulations to manage rangeland resources. Rangeland rules and regulations should be based on the management of livestock management during grazing and harvesting of rangeland resources. The harvesting of woody and good timing of application of fire can also reduce the spread of bush encroachment. Veld resting and rotational grazing can also improve fuel load which is required for burning of woody plants. Furthermore, Department of agriculture should also provide workshops or training to communal farmers use different approaches or cheap ways of reducing bush encroachment and conserving rangeland resources.
- Full Text:
- Date Issued: 2016
- Authors: Tokozwayo, Sive
- Date: 2016
- Subjects: Range management -- South Africa -- Eastern Cape Brush -- Control -- South Africa -- Eastern Cape Communal rangelands -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/2733 , vital:28066
- Description: Communal rangelands occupy 13 percent of the agricultural land in South Africa, and these rangelands serve as a source of feed to livestock. These areas are threatened by bush encroachment due to poor rangeland management. This study was conducted in Alice (Sheshegu communal area) and the objective was to assess farmers' perceptions and the impact of bush encroachment on herbaceous vegetation and soil nutrients. Structured questionnaires were used to assess indigenous knowledge of communal farmers on the impact of bush encroachment on rangelands. Fourty (40) respondents from households who owned livestock were randomly selected and interviewed at Sheshegu village. About 89 percent of communal farmers perceived that change of their grasslands to encroached savannas was caused by unreliable rainfall, prolonged drought, and poor rangeland management. Rangeland assessment was performed at four sites (Scattered, Moderate, Mixed and Dense bushland. 100mx50m were demarcated per site, and four 100m transects were laid parallel to each other, 30m apart. The step point method was used to determine both species composition and basal cover. Biomass production was determined by harvesting forage within randomly-paced a 0.25m2 quadrats. Aristada congesta and Eragrostis obtuse were the most dominating grass species in dense, mixed and moderate bushland. Scattered bushland was dominated by Themeda triandra. Biomass production increases with increase in bush density and basal cover improved from winter to summer season. Increaser grass species increase with the increase in bush density, this indicated that the rangeland was poorly managed and palatable species were being replaced by less palatable ones. Species composition of woody plants was determined within a 200m2 belt transect in all sites. Maytenus polycantha, Aloe ferox, Erehia rigida and lucas capensis were the most dominant woody species in Mixed bushland while Acacia karroo was most dominated in Scattered, Moderate and Dense bushland. Woody density showed no significant differences (P> 0.05) between Dense, Mixed and Moderate bushland. Woody plant density in all these sites exceed 2500 plants/ha, which showed that the rangeland was encroached with woody plants. Soil nutrient content was determined for each site. Five samples of soil were collected per site to test the effect of bush encroachment on soil nutrient composition. The concentration of nitrogen and soil pH increased with increase in bush density, while that of potassium, phosphorous, magnesium, sodium and sulphur showed no significant differences (P>0.05) across all homogenous vegetation units. The study revealed that Sheshegu communal farmers are aware of both negative and positive effects of encroachment on their community, and also argue that the government is not willing to support communal farmers in the process of reducing the spread of bush encroachment. It was concluded that the concentration of nitrogen and soil pH increased with increasing bush density and that bush encroachment had negative effects on herbaceous species. It was recommended that communal farmers should be formulating rangeland rules and regulations to manage rangeland resources. Rangeland rules and regulations should be based on the management of livestock management during grazing and harvesting of rangeland resources. The harvesting of woody and good timing of application of fire can also reduce the spread of bush encroachment. Veld resting and rotational grazing can also improve fuel load which is required for burning of woody plants. Furthermore, Department of agriculture should also provide workshops or training to communal farmers use different approaches or cheap ways of reducing bush encroachment and conserving rangeland resources.
- Full Text:
- Date Issued: 2016
A contribution to the oceanology of the Prince Edward Islands
- Authors: Parker, Llewellyn Derek
- Date: 1985
- Subjects: Oceanography -- Prince Edward Islands
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5605 , http://hdl.handle.net/10962/d1002055
- Description: While the terrestrial ecosystem of the Prince Edward Island Group has been subject to intensive research, the marine ecosystem has to a large extent been neglected. This together with the possible existence of an "island effect" at these islands, as was first proposed after the visit to these islands of the French vessel Marion Dufresne, led to the initiation of a programme to determine the distribution of standing stocks and the productivity of phytoplankton and zooplankton in the neritic seas of these islands. To do this and before a detailed biological survey could be attempted, it was first necessary to define the physical and chemical properties of the circuminsular waters. This dissertation discusses the results of several surveys to these islands in the light of a possible "island effect" and comments upon processes likely to influence such an effect
- Full Text:
- Date Issued: 1985
- Authors: Parker, Llewellyn Derek
- Date: 1985
- Subjects: Oceanography -- Prince Edward Islands
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5605 , http://hdl.handle.net/10962/d1002055
- Description: While the terrestrial ecosystem of the Prince Edward Island Group has been subject to intensive research, the marine ecosystem has to a large extent been neglected. This together with the possible existence of an "island effect" at these islands, as was first proposed after the visit to these islands of the French vessel Marion Dufresne, led to the initiation of a programme to determine the distribution of standing stocks and the productivity of phytoplankton and zooplankton in the neritic seas of these islands. To do this and before a detailed biological survey could be attempted, it was first necessary to define the physical and chemical properties of the circuminsular waters. This dissertation discusses the results of several surveys to these islands in the light of a possible "island effect" and comments upon processes likely to influence such an effect
- Full Text:
- Date Issued: 1985
The impact of non-compliance with Eskom procurement policies
- Authors: Mvelase, Thokozile Olivia
- Date: 2015
- Subjects: Eskom (Firm) , Industrial procurement -- Management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/9140 , vital:26468
- Description: Supply Chain Management (SCM) has an overwhelming impact on firms as it directly impacts on sales and costs. Therefore, it must be a core competency for any organization and thus SCM expertise is highly valued in organisations. Procurement of goods and services has a major impact on the successful execution of the project. Procurement can help the business, ensuring that all the goods and services they buy will be of the right quality, quantity and price, and they will be delivered ‘just in time’. The application of procurement policies and practices, using fair and open procedures, is crucial not only for attracting efficient contractors and suppliers, but also to safeguard the principle of accountability and the cost-effective use of funds. Before awarding a tender, there is a substantial amount of work to be undertaken by the project manager, contracts manager, end user, buyer, and authorising committees. Commitment from personnel involved in contract awarding is not adequate. Furthermore, the Eskom governance process sometimes contributes to delays in awarding a contract. before the enquiry and tender documentation is sent out to the suppliers on the tender list, the core team involved in the procurement process verifies that the enquiry is complete and correct. Should there be contractual or legal issues during the execution of the project in the form of say a contract that has been issued with unsuitable clauses, solving the problem becomes difficult. Contractors will sometimes use contract clauses to suit themselves, and take advantage of the employer, causing cost overruns due to the difficulties in managing the contract. Eskom’s commercial activities are governed by the Public Finance Management Act (PFMA) and Constitution of South Africa, which states that an organisation such as Eskom should have in place “an appropriate procurement and provisioning system which is fair, equitable, transparent, competitive, and cost-effective.” This can eliminate irregularities in contracts, since they can have a serious economic impact, interfere with fair competition, and destroy confidence in the integrity and functioning of public administration Such irregularities may lead to costs overruns on projects where incompetent contractors are awarded a contract. Incorrect financial forecasting is a very serious issue, and needs to be addressed in order to help strengthen the cash flow and forecasting within Eskom. This research strategy is intended for quantifying observations of human behaviour, with the emphasis on exact measurements. The primary data for this study was generated through the administration of a structured questionnaire survey conducted among engineers, project managers, contract managers, and forensics personnel. The secondary data for the present study was gathered from literature in the form of open ended questionnaire from the same personnel. Poor commitment of buyers and chain approval meetings being shifted affect the delays in awarding of contracts. Lack of training of contract managers, absence of legal representative’s advice and squad checking meetings not being represented properly contributes to contracts being awarded with unsuitable clauses. Managers specifically forcing contracts to be awarded to a specific contractor, nepotism or favoritism, politics and contractor greediness, relate to irregularities in contracts. Lack of experience, revision of scope (unclarified scope), project delays, less effort being made when forecasting and unforeseen circumstances, such as strikes, and forces of nature, relate to incorrect financial forecasting. Continuous training and commitment of all personnel involved in the project environment is important, therefore Eskom personnel in the project environment should work as a team in an integrated way. Adequate time should be spent, and thorough checks made, to ensure that documents sent out for tendering conform to requirements. Involvement of all the supporting functions must be maximised. Code of ethics training and application is very crucial in the project environment, and the current governance policies should be adhered to by all stakeholders in the project.
- Full Text:
- Date Issued: 2015
- Authors: Mvelase, Thokozile Olivia
- Date: 2015
- Subjects: Eskom (Firm) , Industrial procurement -- Management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/9140 , vital:26468
- Description: Supply Chain Management (SCM) has an overwhelming impact on firms as it directly impacts on sales and costs. Therefore, it must be a core competency for any organization and thus SCM expertise is highly valued in organisations. Procurement of goods and services has a major impact on the successful execution of the project. Procurement can help the business, ensuring that all the goods and services they buy will be of the right quality, quantity and price, and they will be delivered ‘just in time’. The application of procurement policies and practices, using fair and open procedures, is crucial not only for attracting efficient contractors and suppliers, but also to safeguard the principle of accountability and the cost-effective use of funds. Before awarding a tender, there is a substantial amount of work to be undertaken by the project manager, contracts manager, end user, buyer, and authorising committees. Commitment from personnel involved in contract awarding is not adequate. Furthermore, the Eskom governance process sometimes contributes to delays in awarding a contract. before the enquiry and tender documentation is sent out to the suppliers on the tender list, the core team involved in the procurement process verifies that the enquiry is complete and correct. Should there be contractual or legal issues during the execution of the project in the form of say a contract that has been issued with unsuitable clauses, solving the problem becomes difficult. Contractors will sometimes use contract clauses to suit themselves, and take advantage of the employer, causing cost overruns due to the difficulties in managing the contract. Eskom’s commercial activities are governed by the Public Finance Management Act (PFMA) and Constitution of South Africa, which states that an organisation such as Eskom should have in place “an appropriate procurement and provisioning system which is fair, equitable, transparent, competitive, and cost-effective.” This can eliminate irregularities in contracts, since they can have a serious economic impact, interfere with fair competition, and destroy confidence in the integrity and functioning of public administration Such irregularities may lead to costs overruns on projects where incompetent contractors are awarded a contract. Incorrect financial forecasting is a very serious issue, and needs to be addressed in order to help strengthen the cash flow and forecasting within Eskom. This research strategy is intended for quantifying observations of human behaviour, with the emphasis on exact measurements. The primary data for this study was generated through the administration of a structured questionnaire survey conducted among engineers, project managers, contract managers, and forensics personnel. The secondary data for the present study was gathered from literature in the form of open ended questionnaire from the same personnel. Poor commitment of buyers and chain approval meetings being shifted affect the delays in awarding of contracts. Lack of training of contract managers, absence of legal representative’s advice and squad checking meetings not being represented properly contributes to contracts being awarded with unsuitable clauses. Managers specifically forcing contracts to be awarded to a specific contractor, nepotism or favoritism, politics and contractor greediness, relate to irregularities in contracts. Lack of experience, revision of scope (unclarified scope), project delays, less effort being made when forecasting and unforeseen circumstances, such as strikes, and forces of nature, relate to incorrect financial forecasting. Continuous training and commitment of all personnel involved in the project environment is important, therefore Eskom personnel in the project environment should work as a team in an integrated way. Adequate time should be spent, and thorough checks made, to ensure that documents sent out for tendering conform to requirements. Involvement of all the supporting functions must be maximised. Code of ethics training and application is very crucial in the project environment, and the current governance policies should be adhered to by all stakeholders in the project.
- Full Text:
- Date Issued: 2015
Using the larval parasitoid, Agathis bishopi (Nixon) (Hymenoptera: Braconidae), for early detection of false codling moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) infested fruit
- Authors: Zimba, Kennedy Josaya
- Date: 2015
- Subjects: Cryptophlebia leucotreta , Citrus -- Diseases and pests -- South Africa , Pests -- Biological control -- South Africa , Cryptophlebia leucotreta -- Detection , Parasitoids -- Hosts , Braconidae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5919 , http://hdl.handle.net/10962/d1017186
- Description: Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is one of the major citrus pests of economic importance for South Africa’s citrus industry. It is endemic to Africa, and therefore a phytosanitary pest with zero tolerance by most export markets. The cryptic nature of T. leucotreta makes visual inspection an inefficient method for detecting neonate larvae in fruit in the packhouse. Therefore, a more accurate method for sorting infested fruit at the packhouse, particularly for newly infested fruit could ensure market access. A recent study showed that fruit infested by T. leucotreta emit a chemical profile different from that of a healthy fruit. Several studies provide evidence that parasitoids locate their hosts feeding on fruit by exploiting the novel chemical profiles produced due to host herbivory. The aim of this study was to evaluate the potential of using the naturally occurring behaviour of a larval parasitoid Agathis bishopi (Nixon) (Hymenoptera: Braconidae) for detection of T. leucotreta infested fruit, by determining which compound in infested fruit is attractive to parasitoids. Ytube olfactometer and flight-tunnel bioassays with healthy and T. leucotreta infested fruit showed a significantly stronger response of A. bishopi female parasitoids to infested fruit. Among the volatile compounds associated with T. leucotreta infested fruit, D-limonene elicited the strongest attraction to A. bishopi female parasitoids. Attraction of mated A. bishopi female parasitoids to T. leucotreta infested fruit and D-limonene significantly increased after oviposition experience. Behavioural responses of A. bishopi female parasitoids that were associated with T. leucotreta infested fruit were investigated to determine which behaviours are distinct and interpretable. Probing and oviposition behaviours were the most noticeable and were only elicited on infested fruit when parasitoids contacted T. leucotreta frass, indicating that chemical compounds in frass are short-range cues used for final host location. Since production of D-limonene by fruit is elevated due to herbivory by different pests including mechanical injury on fruit, response of A. bishopi female parasitoids to compounds in frass offers a more specific and potentially useful mechanism for development of a detection system for T. leucotreta infested fruit. Chemical analysis of T. leucotreta frass and conditioning A. bishopi parasitoids to respond behaviourally to compounds in frass is proposed.
- Full Text:
- Date Issued: 2015
- Authors: Zimba, Kennedy Josaya
- Date: 2015
- Subjects: Cryptophlebia leucotreta , Citrus -- Diseases and pests -- South Africa , Pests -- Biological control -- South Africa , Cryptophlebia leucotreta -- Detection , Parasitoids -- Hosts , Braconidae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5919 , http://hdl.handle.net/10962/d1017186
- Description: Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is one of the major citrus pests of economic importance for South Africa’s citrus industry. It is endemic to Africa, and therefore a phytosanitary pest with zero tolerance by most export markets. The cryptic nature of T. leucotreta makes visual inspection an inefficient method for detecting neonate larvae in fruit in the packhouse. Therefore, a more accurate method for sorting infested fruit at the packhouse, particularly for newly infested fruit could ensure market access. A recent study showed that fruit infested by T. leucotreta emit a chemical profile different from that of a healthy fruit. Several studies provide evidence that parasitoids locate their hosts feeding on fruit by exploiting the novel chemical profiles produced due to host herbivory. The aim of this study was to evaluate the potential of using the naturally occurring behaviour of a larval parasitoid Agathis bishopi (Nixon) (Hymenoptera: Braconidae) for detection of T. leucotreta infested fruit, by determining which compound in infested fruit is attractive to parasitoids. Ytube olfactometer and flight-tunnel bioassays with healthy and T. leucotreta infested fruit showed a significantly stronger response of A. bishopi female parasitoids to infested fruit. Among the volatile compounds associated with T. leucotreta infested fruit, D-limonene elicited the strongest attraction to A. bishopi female parasitoids. Attraction of mated A. bishopi female parasitoids to T. leucotreta infested fruit and D-limonene significantly increased after oviposition experience. Behavioural responses of A. bishopi female parasitoids that were associated with T. leucotreta infested fruit were investigated to determine which behaviours are distinct and interpretable. Probing and oviposition behaviours were the most noticeable and were only elicited on infested fruit when parasitoids contacted T. leucotreta frass, indicating that chemical compounds in frass are short-range cues used for final host location. Since production of D-limonene by fruit is elevated due to herbivory by different pests including mechanical injury on fruit, response of A. bishopi female parasitoids to compounds in frass offers a more specific and potentially useful mechanism for development of a detection system for T. leucotreta infested fruit. Chemical analysis of T. leucotreta frass and conditioning A. bishopi parasitoids to respond behaviourally to compounds in frass is proposed.
- Full Text:
- Date Issued: 2015
Using captive seabirds to assess knowledge gaps in stable isotope analysis of diets
- Authors: Micklem, Isabel Andrea
- Date: 2019
- Subjects: Stable isotopes -- Analysis African penguin -- South Africa Breeding
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/65101 , vital:28686
- Description: Stable isotope (SI) ratios of carbon (δ13C) and nitrogen (δ15N) are now widely used as biomarkers in ecological studies to provide information about food web structuring. However, understanding trophic relationships using SI analysis requires not only knowledge of SI values of predator and prey, but also accurate discrimination factors (DFs), which can differ among species and by physiological state. This thesis examined three questions using captive birds from the South African Foundation for the Conservation of Coastal Birds (SANCCOB). First, the effects of ontogeny on δ13C and δ15N ratios of African penguins (Spheniscus demersus) were assessed. Blood samples were collected from penguins in four age classes (P3 chicks, blues, juveniles and adults) concurrently with their diet (sardine (Sardinops sagax) and formula). Second, to assess the influence of breeding physiology on SI ratios, the blood of ten breeding pairs of penguins was sampled over a five-month period from June to October 2016. Following laying, each pair was categorised into one of three (four for whole blood) egg production phases (initial yolk deposition, rapid yolk deposition and post-laying) and their influences on SI ratios were tested. Third, species differences in DFs were evaluated for African penguins, kelp and Hartlaub’s gulls (Larus dominicanus and L. hartlaubii), greater crested terns (Thalasseus bergii) and Cape cormorants (Phalacrocorax capensis). Flying birds were mostly fed sardine with a small but unknown amount of sardinella (Sardinella aurita), DFs were therefore estimated for a 50:50 sardine:sardinella diet, a 75:25 sardine:sardinella diet and a 100% sardine diet for each flying bird species. The DFs were assessed for the whole blood (WB), red blood cells (RBC), plasma (PL) and delipidated plasma of the penguins, and only WB for the flying birds as well as flesh, whole fish, delipidated flesh and delipidated whole fish for fish species, and for formula. Results indicated that age influenced both the δ13C and δ15N of WB, only the δ15N of RBC and the δ13C of delipidated PL. The assessment of breeding physiology yielded a significant interaction between the effects of egg production phase and sex on the δ13C of WB; females had significantly lower δ13C in the rapid yolk deposition phase than the other two phases and all males. The δ13C of PL was affected only by sex, with females having a significantly lower δ13C value than males. Neither physiological state nor sex influenced the other blood components. Differences were found among the three DFs in the non-penguin species, but not for all consumer – prey tissue combinations. There were also significant differences among species with a DF calculated from a diet with the most probable prey proportions eaten. Depending on the combination of consumer and prey tissue used to calculate the DF, a different conclusion regarding trophic information can be reached. A literature review updated with the present data showed that no general pattern or grouping of similar species with regards to DF values could be drawn, highlighting the importance of determining species- and tissue-specific DFs. Thus age, egg production, tissue and species all influenced the SI values of bird blood and therefore their DFs. Not all physiological conditions affect all blood components in the same way, making different components more or less sensitive to physiological influences. Though their influence is at a small enough scale that it is unlikely to hamper correct conclusion in ecological studies, it is crucial that these factors are considered when using SI analysis (SIA). When uncertainties exist for some coefficients in wild studies, SIA should therefore be combined to other dietary techniques to determine the food web structure as best as possible.
- Full Text:
- Date Issued: 2019
- Authors: Micklem, Isabel Andrea
- Date: 2019
- Subjects: Stable isotopes -- Analysis African penguin -- South Africa Breeding
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/65101 , vital:28686
- Description: Stable isotope (SI) ratios of carbon (δ13C) and nitrogen (δ15N) are now widely used as biomarkers in ecological studies to provide information about food web structuring. However, understanding trophic relationships using SI analysis requires not only knowledge of SI values of predator and prey, but also accurate discrimination factors (DFs), which can differ among species and by physiological state. This thesis examined three questions using captive birds from the South African Foundation for the Conservation of Coastal Birds (SANCCOB). First, the effects of ontogeny on δ13C and δ15N ratios of African penguins (Spheniscus demersus) were assessed. Blood samples were collected from penguins in four age classes (P3 chicks, blues, juveniles and adults) concurrently with their diet (sardine (Sardinops sagax) and formula). Second, to assess the influence of breeding physiology on SI ratios, the blood of ten breeding pairs of penguins was sampled over a five-month period from June to October 2016. Following laying, each pair was categorised into one of three (four for whole blood) egg production phases (initial yolk deposition, rapid yolk deposition and post-laying) and their influences on SI ratios were tested. Third, species differences in DFs were evaluated for African penguins, kelp and Hartlaub’s gulls (Larus dominicanus and L. hartlaubii), greater crested terns (Thalasseus bergii) and Cape cormorants (Phalacrocorax capensis). Flying birds were mostly fed sardine with a small but unknown amount of sardinella (Sardinella aurita), DFs were therefore estimated for a 50:50 sardine:sardinella diet, a 75:25 sardine:sardinella diet and a 100% sardine diet for each flying bird species. The DFs were assessed for the whole blood (WB), red blood cells (RBC), plasma (PL) and delipidated plasma of the penguins, and only WB for the flying birds as well as flesh, whole fish, delipidated flesh and delipidated whole fish for fish species, and for formula. Results indicated that age influenced both the δ13C and δ15N of WB, only the δ15N of RBC and the δ13C of delipidated PL. The assessment of breeding physiology yielded a significant interaction between the effects of egg production phase and sex on the δ13C of WB; females had significantly lower δ13C in the rapid yolk deposition phase than the other two phases and all males. The δ13C of PL was affected only by sex, with females having a significantly lower δ13C value than males. Neither physiological state nor sex influenced the other blood components. Differences were found among the three DFs in the non-penguin species, but not for all consumer – prey tissue combinations. There were also significant differences among species with a DF calculated from a diet with the most probable prey proportions eaten. Depending on the combination of consumer and prey tissue used to calculate the DF, a different conclusion regarding trophic information can be reached. A literature review updated with the present data showed that no general pattern or grouping of similar species with regards to DF values could be drawn, highlighting the importance of determining species- and tissue-specific DFs. Thus age, egg production, tissue and species all influenced the SI values of bird blood and therefore their DFs. Not all physiological conditions affect all blood components in the same way, making different components more or less sensitive to physiological influences. Though their influence is at a small enough scale that it is unlikely to hamper correct conclusion in ecological studies, it is crucial that these factors are considered when using SI analysis (SIA). When uncertainties exist for some coefficients in wild studies, SIA should therefore be combined to other dietary techniques to determine the food web structure as best as possible.
- Full Text:
- Date Issued: 2019
A polarographic study : the estimation of sodium and potassium in the presence of each other
- Authors: Carter, Austin John
- Date: 1938
- Subjects: Polarographs , Polarography , Potassium , Sodium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4455 , http://hdl.handle.net/10962/d1010434
- Description: The polarographic method has been described, and an attempt made to describe the difficulty of the simultaneous deposition of sodium and potassium. Various methods have been examined, of which precipitation of potassium with magnesium dipicrylaminate seems the most promising. The quantitative results were unsatisfactory, and possible sources of error are discussed. The method, while very convenient, rapid and labour-saving, is not sufficiently standardised to be trustworthy.
- Full Text:
- Date Issued: 1938
- Authors: Carter, Austin John
- Date: 1938
- Subjects: Polarographs , Polarography , Potassium , Sodium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4455 , http://hdl.handle.net/10962/d1010434
- Description: The polarographic method has been described, and an attempt made to describe the difficulty of the simultaneous deposition of sodium and potassium. Various methods have been examined, of which precipitation of potassium with magnesium dipicrylaminate seems the most promising. The quantitative results were unsatisfactory, and possible sources of error are discussed. The method, while very convenient, rapid and labour-saving, is not sufficiently standardised to be trustworthy.
- Full Text:
- Date Issued: 1938
The biomass production, nutrient content and silage quality of Perennial ryegrass (Lolium perenne (L)) Cocksfoot (Dactylis glomerata (L)) and Tall fescue (Festuca arundinacea (Schreb)) varieties grown under irrigation in Alice, South Africa
- Authors: Tikwayo, Sizwe Edward
- Date: 2016
- Subjects: Ryegrasses -- Varieties -- South Africa -- Eastern Cape Ryegrasses -- Irrigation -- South Africa -- Eastern Cape Biomass energy -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/1796 , vital:27560
- Description: The study aims to evaluate the biomass production and nutrient content and silage quality of perennial ryegrass (Lolium perenne (L)), cocksfoot (Dactylis glomerata (L)) and tall fescue (Festuca arundinacea (Schreb)). Six varieties were used, two for each species. A completely randomized block designed replicated three times was conducted at University of Fort Hare Research Farm during 2014-2015 growing season. The plots were harvested at four-week interval (post emergency) for one year. Biomass yields were measured for fresh forage and dry matter yield. Duplicated samples were then dried, milled and analyzed for chemical and mineral composition (CP, NDF, ADF, and ash, Ca, P, K, Na, Mn, Cu, Zn and Fe) for only winter season. In addition the grasses were ensiled and the silage was analyzed for its fermentation parameters and nutrient content (lactic acid, pH, DM, CP, NDF, ADF, and ash, Ca, P, K, Na, Mn, Cu, Zn and Fe). Biomass results showed significant differences (P < 0.05) between season and varieties. On average Tall fescue varieties Jessup (13741.67 FM kg/ha), Alix (12007.78 FM kg/ ha) and Ryegrass varieties Samson (11597.22 FM kg/ha) and Nui (10591.67 FM kg/ha) had the highest fresh biomass yield. Similarly, Tall fescue varieties Jessup (2833.06 DM kg/ha) and Alix (2708.3 DM kg/ ha) and Ryegrass varieties Samson (2169.44 DM kg/ha) and Nui (2169.67 kg/ha) had the highest dry biomass yield. Throughout the year the average biomass yield was significantly different among species (P< 0.05). During summer and autumn Tall fescue varieties Jessup and Alix gave the highest dry matter yields of 3855.5 to 1977.8 DM kg/ha, and 3877.8 to 1900 DM kg/ha, respectively, and followed by Cocksfoot 2400 DM kg/ha. Ryegrass had the highest dry matter biomass yield in winter (2975 DM kg/ha) and the least in summer (977.75 DM kg/ha). There were no significant (P>0.05) differences on the chemical composition (CP, NDF, ADF, and ash) and mineral composition (Ca, P, K, Na, Mn, Cu, Zn and Fe) of the six varieties. The grass silage results showed significant differences (P< 0.05) among the six varieties for moisture content. Perennial ryegrass variety Nui (66.76 percent) had low moisture content than the other grass silages. The different varieties had no significant effects (P>0.05) on chemical composition (CP, NDF, ADF, and ash) and mineral composition (Ca, P, K, Na, Mn, Cu, Zn and Fe). It is concluded that the biomass production of the six varieties of three grass species was different throughout the year under irrigation hence Ryegrass and Tall fescue are recommended for dairy farmers in the region for all seasons. It can be concluded that there is no difference with respect to fermentation characteristics and nutrient content among the varieties of the grass species.
- Full Text:
- Date Issued: 2016
- Authors: Tikwayo, Sizwe Edward
- Date: 2016
- Subjects: Ryegrasses -- Varieties -- South Africa -- Eastern Cape Ryegrasses -- Irrigation -- South Africa -- Eastern Cape Biomass energy -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/1796 , vital:27560
- Description: The study aims to evaluate the biomass production and nutrient content and silage quality of perennial ryegrass (Lolium perenne (L)), cocksfoot (Dactylis glomerata (L)) and tall fescue (Festuca arundinacea (Schreb)). Six varieties were used, two for each species. A completely randomized block designed replicated three times was conducted at University of Fort Hare Research Farm during 2014-2015 growing season. The plots were harvested at four-week interval (post emergency) for one year. Biomass yields were measured for fresh forage and dry matter yield. Duplicated samples were then dried, milled and analyzed for chemical and mineral composition (CP, NDF, ADF, and ash, Ca, P, K, Na, Mn, Cu, Zn and Fe) for only winter season. In addition the grasses were ensiled and the silage was analyzed for its fermentation parameters and nutrient content (lactic acid, pH, DM, CP, NDF, ADF, and ash, Ca, P, K, Na, Mn, Cu, Zn and Fe). Biomass results showed significant differences (P < 0.05) between season and varieties. On average Tall fescue varieties Jessup (13741.67 FM kg/ha), Alix (12007.78 FM kg/ ha) and Ryegrass varieties Samson (11597.22 FM kg/ha) and Nui (10591.67 FM kg/ha) had the highest fresh biomass yield. Similarly, Tall fescue varieties Jessup (2833.06 DM kg/ha) and Alix (2708.3 DM kg/ ha) and Ryegrass varieties Samson (2169.44 DM kg/ha) and Nui (2169.67 kg/ha) had the highest dry biomass yield. Throughout the year the average biomass yield was significantly different among species (P< 0.05). During summer and autumn Tall fescue varieties Jessup and Alix gave the highest dry matter yields of 3855.5 to 1977.8 DM kg/ha, and 3877.8 to 1900 DM kg/ha, respectively, and followed by Cocksfoot 2400 DM kg/ha. Ryegrass had the highest dry matter biomass yield in winter (2975 DM kg/ha) and the least in summer (977.75 DM kg/ha). There were no significant (P>0.05) differences on the chemical composition (CP, NDF, ADF, and ash) and mineral composition (Ca, P, K, Na, Mn, Cu, Zn and Fe) of the six varieties. The grass silage results showed significant differences (P< 0.05) among the six varieties for moisture content. Perennial ryegrass variety Nui (66.76 percent) had low moisture content than the other grass silages. The different varieties had no significant effects (P>0.05) on chemical composition (CP, NDF, ADF, and ash) and mineral composition (Ca, P, K, Na, Mn, Cu, Zn and Fe). It is concluded that the biomass production of the six varieties of three grass species was different throughout the year under irrigation hence Ryegrass and Tall fescue are recommended for dairy farmers in the region for all seasons. It can be concluded that there is no difference with respect to fermentation characteristics and nutrient content among the varieties of the grass species.
- Full Text:
- Date Issued: 2016
Pharmacological Evaluation and Medicinal Potential of Vachellia Karroo (Hayne) Banfi & Galasso Pods traditionally used to treat Sexually Transmitted Diseases in the Eastern Cape, South Africa.
- Authors: Maposa, Sandisiwe
- Date: 2019
- Subjects: Medicinal plants
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14583 , vital:40017
- Description: Vachellia karroo is widely used in folk medicine in the Eastern Cape Province South Africa, however, the pods are usually discarded as waste. The current study was conducted to evaluate the phytochemical content and the antioxidant activity of V. karroo pods. The pods were extracted using acetone, distilled water, hexane and methanol. The total phenol, flavonoid, proanthocyanidin, alkaloid and saponin contents of the various extracts were determined spectrometrically and antioxidant activity was evaluated using inhibition of 2,2-diphenyl-1- picrylhydrazyl (DPPH), 2,2´-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid (ABTS), nitric oxide (NO) radicals, while total antioxidant capacity (TAC) was estimated by the phosphomolybdenum assay. V. karro pods had significant amounts of total phenols, flavonoids and proanthocynadin, although, proanthocynadin was not detected in the aqueous and hexane extracts. Methanol and acetone extracts showed higher phenolic, proanthocynadin and flavonoids contents (52.47 ± 6.82 and 29.31 ± 1.49), (334.8±85.1 and 231.22 ±1.80),(288±4.26 & 208.2±17.7) compared to the aqueous and hexane extracts. The alkaloid and saponin contents were 26.67 and 12.85 % respectively. The IC50 values of the methanol extract for DPPH, ABTS and total antioxidant capacity (TAC) were 0.345, 0.017 and 0.116 mg/mL, respectively. Methanol extract of V. karroo pod showed higher polyphenolic content of all the extracts analysed with corresponding strong free radical scavenging potential. These underutilized pods could serve as a new source of antioxidant compounds which could help in combating various ailments. The great antioxidant activity displayed by V. karroo pods extract supports the therapeutic use of this plant in traditional medicine and are attributed to the phytochemical content.The current information suggests that extracts from Vachellia karroo pods might be a ix cheap potential source of natural antioxidants that could be of great importance for the treatment of free radical related diseases. Furthermore, it makes a case for the utilization of the pods instead of discarding them as waste materials. The evaluation of antimicrobial potential of Vachellia karroo extracts was carried out using agar dilution assay against 8 bacterial strains-4 gram-positive [ Enterococcus faecalis (ATCC 29212), Staphylococcus aureus (OK), Bacillus subtilis KZN, Bacillus cereus, and Streptococcus pyogenes] and 4 gram-negative strains[ Vibrio cholera, Klebsiella pneumonia (ATCC 4352), Pseudomonas aeruginosa (ATCC 19582), Salmonella typhi (OK) ]. Six fungal isolates[ Trichophyton mucoides ATCC 201382, Candida albicans (ATCC 10231), Candida glabatra, Penicillium chrysogenum, Aspergillus fumigatus, Penicillum aurantiogriseum] were usedor antifungal assessment. The methanol extract exhibited broad-spectrum activity, with Gram-positive strains being more sensitive than Gram-negative strains. The extracts also showed great inhibition against Candida albicans the fungal isolate responsible for causing candidiasis in women. Since the pods showed promising antimicrobial activity, they could serve as a cheap source for the treatment and management of these sexually transmitted infections. The brine shrimp toxicity test revealed successful hatching of the cysts was in the order: Aqueous extract> methanol extract> hexane extract> acetone extract. The hatching of nauplii was in a concentration dependent fashion, with hatching success decreasing with increase in concentration of extracts. Lethality of extracts determined based on Meyerʼs index of toxicity, showed that the acetone and hexane extracts of V. karroo were moderately toxic. The results of this study indicated that aqueous and methanolic extracts of Vachellia karroo pods were not toxic, therefore supporting its traditional therapeutic usage. This implies that rather than discard x the pods as is waste as it being currently done, Vachellia karroo pods could be salvaged and processed along with the leaves, thus reducing environmental pollution. Proximate parameters (moisture, ash, crude fibre, crude fat, proteins, and carbohydrate) were evaluated using ALASA methods, and elemental analysis by ICP-OES technique. Nutritional analysis showed that V. karroo pods had low content of crude fat and high content of crude fibre, ash, crude protein, and carbohydrate sufficient to meet the recommended dietary allowances. The pods were rich in major minerals Ca, K, P and Mg, with sufficient amount of trace elements Na, Fe, Zn, and Cu. The outcome of this study suggests that Vachellia karroo pods have good nutritional potentials to support or complement the recommended dietary allowance and could be a cheap source of essential nutrients that could help in ameliorating most nutritional challenges as well as contribute remarkably to the amount of nutrient intake in human and animal diets.
- Full Text:
- Date Issued: 2019
- Authors: Maposa, Sandisiwe
- Date: 2019
- Subjects: Medicinal plants
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14583 , vital:40017
- Description: Vachellia karroo is widely used in folk medicine in the Eastern Cape Province South Africa, however, the pods are usually discarded as waste. The current study was conducted to evaluate the phytochemical content and the antioxidant activity of V. karroo pods. The pods were extracted using acetone, distilled water, hexane and methanol. The total phenol, flavonoid, proanthocyanidin, alkaloid and saponin contents of the various extracts were determined spectrometrically and antioxidant activity was evaluated using inhibition of 2,2-diphenyl-1- picrylhydrazyl (DPPH), 2,2´-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid (ABTS), nitric oxide (NO) radicals, while total antioxidant capacity (TAC) was estimated by the phosphomolybdenum assay. V. karro pods had significant amounts of total phenols, flavonoids and proanthocynadin, although, proanthocynadin was not detected in the aqueous and hexane extracts. Methanol and acetone extracts showed higher phenolic, proanthocynadin and flavonoids contents (52.47 ± 6.82 and 29.31 ± 1.49), (334.8±85.1 and 231.22 ±1.80),(288±4.26 & 208.2±17.7) compared to the aqueous and hexane extracts. The alkaloid and saponin contents were 26.67 and 12.85 % respectively. The IC50 values of the methanol extract for DPPH, ABTS and total antioxidant capacity (TAC) were 0.345, 0.017 and 0.116 mg/mL, respectively. Methanol extract of V. karroo pod showed higher polyphenolic content of all the extracts analysed with corresponding strong free radical scavenging potential. These underutilized pods could serve as a new source of antioxidant compounds which could help in combating various ailments. The great antioxidant activity displayed by V. karroo pods extract supports the therapeutic use of this plant in traditional medicine and are attributed to the phytochemical content.The current information suggests that extracts from Vachellia karroo pods might be a ix cheap potential source of natural antioxidants that could be of great importance for the treatment of free radical related diseases. Furthermore, it makes a case for the utilization of the pods instead of discarding them as waste materials. The evaluation of antimicrobial potential of Vachellia karroo extracts was carried out using agar dilution assay against 8 bacterial strains-4 gram-positive [ Enterococcus faecalis (ATCC 29212), Staphylococcus aureus (OK), Bacillus subtilis KZN, Bacillus cereus, and Streptococcus pyogenes] and 4 gram-negative strains[ Vibrio cholera, Klebsiella pneumonia (ATCC 4352), Pseudomonas aeruginosa (ATCC 19582), Salmonella typhi (OK) ]. Six fungal isolates[ Trichophyton mucoides ATCC 201382, Candida albicans (ATCC 10231), Candida glabatra, Penicillium chrysogenum, Aspergillus fumigatus, Penicillum aurantiogriseum] were usedor antifungal assessment. The methanol extract exhibited broad-spectrum activity, with Gram-positive strains being more sensitive than Gram-negative strains. The extracts also showed great inhibition against Candida albicans the fungal isolate responsible for causing candidiasis in women. Since the pods showed promising antimicrobial activity, they could serve as a cheap source for the treatment and management of these sexually transmitted infections. The brine shrimp toxicity test revealed successful hatching of the cysts was in the order: Aqueous extract> methanol extract> hexane extract> acetone extract. The hatching of nauplii was in a concentration dependent fashion, with hatching success decreasing with increase in concentration of extracts. Lethality of extracts determined based on Meyerʼs index of toxicity, showed that the acetone and hexane extracts of V. karroo were moderately toxic. The results of this study indicated that aqueous and methanolic extracts of Vachellia karroo pods were not toxic, therefore supporting its traditional therapeutic usage. This implies that rather than discard x the pods as is waste as it being currently done, Vachellia karroo pods could be salvaged and processed along with the leaves, thus reducing environmental pollution. Proximate parameters (moisture, ash, crude fibre, crude fat, proteins, and carbohydrate) were evaluated using ALASA methods, and elemental analysis by ICP-OES technique. Nutritional analysis showed that V. karroo pods had low content of crude fat and high content of crude fibre, ash, crude protein, and carbohydrate sufficient to meet the recommended dietary allowances. The pods were rich in major minerals Ca, K, P and Mg, with sufficient amount of trace elements Na, Fe, Zn, and Cu. The outcome of this study suggests that Vachellia karroo pods have good nutritional potentials to support or complement the recommended dietary allowance and could be a cheap source of essential nutrients that could help in ameliorating most nutritional challenges as well as contribute remarkably to the amount of nutrient intake in human and animal diets.
- Full Text:
- Date Issued: 2019
Preliminary investigation of the molecular pathogenicity determinants of Xanthomonas campestris pv. zeae
- Authors: Downing, T G
- Date: 1998
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4066 , http://hdl.handle.net/10962/d1004922
- Description: Xanthomonas campestris pv. zeae was shown to posses a vast range of potential plant cell wall degrading enzymes including at least one protease, a carboxymethylcellulase, pectin lyase, polygalacturonase and a B-endoglucanase. Replicon stability and transfer system efficiencies were determined for a range of oriC, and oriT -tra combinations, and suitable vectors were constructed and identified for insertional inactivation by homologous recombination. Ideal suicide replicons were found to be pACYC184 and p15A, while P, Wand Q group replicons were supported by X campestris pv. zeae. Group P and group N transfer systems were shown to be highly efficient in intra-genus matings between Escherichia coli and X campestris pv. zeae, with the exception of P-tra systems in trans for the delivery of Tn5. Various cloning vectors were tested for stability and mobility. Tn5 was shown to transpose at high frequencies into the genome of the bacterial plant pathogen, and insertion was relatively random. Suitable screening assays were established to allow rapid isolation of mutants with potential virulence or pathogenic deviations, after mutagenesis. Two non-pathogenic mutants were identified, one of which was a putative hrp·, while the other was a leaky virulence. A single mutant showing 40% reduced protease activity was also shown to exhibit reduced virulence indicating a minor role for the protease in pathogenicity. The majority of virulence mutants showed altered growth in different levels of nutritional availability and complexity. Nutritional viability (the ability to acquire and use nutrients at a sufficient rate to grow fast enough to overcome host defences) was shown to be essential for virulence and possibly pathogenicity. Wild-type in-planta behaviour was analysed and growth and spread patterns typical for pathogenic response identified. Chief amongst these was the requirement for a threshold level of cells per leaf area or length, before symptoms could develop. Occlusion of vascular bundles was shown not to be the primary factor in the pathogenicity of X campestris pv. zeae. Threshold levels for lesion development indicate the absence of a diffusable lesion forming element, and possibly the requirement of cell density for induction of certain functions. , KMBT_363
- Full Text:
- Date Issued: 1998
- Authors: Downing, T G
- Date: 1998
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4066 , http://hdl.handle.net/10962/d1004922
- Description: Xanthomonas campestris pv. zeae was shown to posses a vast range of potential plant cell wall degrading enzymes including at least one protease, a carboxymethylcellulase, pectin lyase, polygalacturonase and a B-endoglucanase. Replicon stability and transfer system efficiencies were determined for a range of oriC, and oriT -tra combinations, and suitable vectors were constructed and identified for insertional inactivation by homologous recombination. Ideal suicide replicons were found to be pACYC184 and p15A, while P, Wand Q group replicons were supported by X campestris pv. zeae. Group P and group N transfer systems were shown to be highly efficient in intra-genus matings between Escherichia coli and X campestris pv. zeae, with the exception of P-tra systems in trans for the delivery of Tn5. Various cloning vectors were tested for stability and mobility. Tn5 was shown to transpose at high frequencies into the genome of the bacterial plant pathogen, and insertion was relatively random. Suitable screening assays were established to allow rapid isolation of mutants with potential virulence or pathogenic deviations, after mutagenesis. Two non-pathogenic mutants were identified, one of which was a putative hrp·, while the other was a leaky virulence. A single mutant showing 40% reduced protease activity was also shown to exhibit reduced virulence indicating a minor role for the protease in pathogenicity. The majority of virulence mutants showed altered growth in different levels of nutritional availability and complexity. Nutritional viability (the ability to acquire and use nutrients at a sufficient rate to grow fast enough to overcome host defences) was shown to be essential for virulence and possibly pathogenicity. Wild-type in-planta behaviour was analysed and growth and spread patterns typical for pathogenic response identified. Chief amongst these was the requirement for a threshold level of cells per leaf area or length, before symptoms could develop. Occlusion of vascular bundles was shown not to be the primary factor in the pathogenicity of X campestris pv. zeae. Threshold levels for lesion development indicate the absence of a diffusable lesion forming element, and possibly the requirement of cell density for induction of certain functions. , KMBT_363
- Full Text:
- Date Issued: 1998
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