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‘Signs of our passage’: Examining how Tanzanian irregular transit migrants create a sense of place through their mobile and immobile experiences: a Durban-based case study.
No full textDoctoral Degree. University of KwaZulu-Natal, Durban.In 2020, there were reportedly 281 million international migrants, roughly 3.60 percent of the global population. While most people participate in legal migration, a significant portion of global migration is irregular due to economic, social, environmental and political instability. Africa witnessed a 68 percent increase in transnational migration between 2000 and 2017, originating from the continent. However, scholarship on African mobilities prioritises irregular migration from sub-Saharan Africa to Europe through the Maghreb region. Furthermore, studies on migration in Southern Africa tend to characterise South Africa as a destination country.
Situated within the global phenomenon of irregular transit migration, this study aimed to understand and describe the unique experiences of a Tanzanian irregular transit migrant and stowaway community as they created a sense of place through social and material practices in heterotopic sites in Durban, South Africa. Additionally, the study aimed to understand the community members’ mobile and immobile experiences as they travelled from Tanzania to South Africa with one intention: to stow away on a ship to Europe or the Americas.
The data for this project was collected through 11 qualitative semi-structured interviews with community members and associates. A Reflexive Thematic Analysis (RTA) approach was utilised to interpret the stories elicited from the research participants. The findings contradict research that characterises irregular migrants as passive victims or unscrupulous criminals by demonstrating the polysemic nature of ‘heterotopias of deviance’ as contradictory, intense, and transformative places where identity and belonging are actualised. This perspective departs from the dichotomy of dominance and resistance in spatial thinking. Additionally, the accounts reveal that Durban represented an open-ended pause for this community, which confronted harsh conditions and dangerous encounters through their mobile and immobile experiences en route, in Durban and at sea. This study indicates the need to humanise precarious migrants’ attitudes, motivations and lived experiences to comprehend the complex phenomenon of global irregular transit migration
Ghana’s fertilizer subsidy program (gfsp) and complementarity of agricultural intensification technologies: any role to build household food security resilience?
No full textDoctoral Degree. University of KwaZulu-Natal, PietermaritzburgThere is a decline in recent times of Ghana’s agricultural sector’s contribution to national GDP. In addition, the position of the crops sub-sector slipped from being the second largest economic activity in 2018 to being the third largest economic activity in 2019. Agriculture in Ghana remains largely subsistent, contributing almost 80% of the national food consumption. These declines have risen concerns among policy makers about meeting the country’s food security needs and achieving SDGs 1 and 2. Food insecurity persists in Ghana. For instance, Ghana remains not self-sufficient in maize production. This situation is often blamed on poor yields from farmers’ fields. Decline in soil fertility has been cited in the literature as the cause of low yields. Subsequently, increased use of mineral fertilizers is being promoted in Ghana since it is considered as the alternative to improving crop yields. Climate change/variability and other shocks including increased cost of mineral fertilizer have compelled the government of Ghana to implement the Ghana’s Fertilizer Subsidy Program (GFSP). Consequently, increasing application of mineral fertilizers has been reported in the literature of between six to ten times more since 2010 than it was in the 2000s. The number of farmers using mineral fertilizers has also increased due to Fertilizer Subsidy Programs (FSPs). In the long-run, crop yield tends to increase with the application of mineral fertilizers only when integrated with that of organic materials. This calls for implementation of sustainable production systems that enhance efficiency of mineral fertilizers and soil health. Without widespread adoption of sustainable intensification practices among smallholder farmers, declining soil fertility and food insecurity will persist in SSA.
This study is, therefore, aimed at addressing three identified empirical knowledge gaps in the literature regarding FSPs, farmers’ own investments in promoting intensification practices, rural development, and food (in)security. Firstly, there was the dearth of assessment that is rigorous of the impact of FSPs on sustainable intensification practices. Earlier empirical assessments on FSPs centered on their evolution and concepts, advantages and disadvantages associated with their implementation. These disadvantages finally led to their halt. Evidence exists regarding the impacts of Fertilizer Subsidy Programs (FSPs) on household welfare and input market development. However, studies in the past have not looked at the contribution of FSPs to sustainable intensification practices and, farm inputs in general, among smallholder farmers. Addressing this gap could help policy makers in designing and implementing agricultural policies and programs that address environmental sustainability, climate change-related issues and rural development.
The second identified gap was the paucity of literature on the contribution of FSPs to all the four food security dimensions. Empirical evidence remains limited in explaining food security’s complex nature and its drivers to policy makers and development practitioners. The current approach does not] offer a holistic pathway in addressing food insecurity since it results from multiple drivers such as availability, access, utilization and stability of food. Evaluating what policies, socio-economic characteristics and institutional factors positively impact on these multiple dimensions of food security could help government formulate policies that could reduce food insecurity in Ghana.
The third gap identified was limited attention given to the complementarity of ISFM practices in improving household food security. In addition, exit strategy has not been provided in the current literature for FSPs despite reported evidence of their unsustainability due to capture by people of influence, inefficiencies and poor targeting of program beneficiaries. Widespread adoption of ISFM practices could serve as exit strategies for FSPs, not only in Ghana but SSA as a whole. Empirical studies on the impact of ISFM practices in improving soil organic carbon has largely been limited to field experiments in Ghana. This makes it difficult to relate the impact of ISFM practices to household food security. With proper empirical evidence on the impact of complementarity of ISFM practices on households’ food security using household survey data, policies could be designed to enhance adoption of the complete package of ISFM practices at the plot level.
Following the knowledge gaps identified, the specific objectives of the study were to: (i) assess the extent to which GFSP affected adoption of agricultural intensification technologies and gross farm inputs; (ii) investigate the impact of GFSP on multiple dimensions of household food security; and (iii) examine the impacts of the complementarity of Integrated Soil Fertility Management (ISFM) technologies on multiple dimensions of food security. First, two-stage least squares with instrumental variables (2SLS-IV) and endogenous switching regression (ESR) were used to study the effect of participation in Ghana’s Fertilizer Subsidy Program (GFSP) on the adoption intensity of Sustainable Intensification Practices (SIPs) and gross farm inputs. A nationally representative dataset of 4,365 maize-growing households for two survey periods (2012/13) and (2016/17) who purchased mineral fertilizers was used for the study. The study finds that participation in the GFSP increased the adoption intensity in both SIPs and gross farm inputs. The implication is that investments into climate-smart technologies and gross farm inputs by beneficiaries of GFSP is attributable to participation in the program. This finding explains the crucial role of GFSP as a pro-rural development policy beyond just the provision of mineral fertilizers to smallholder maize farmers to achieve increased productivity. This is because of the forward and backward linkages between rural agricultural input markets and farmers’ direct purchases of farm inputs. The study also found mutual aid schemes, farmer cooperatives, agricultural loans, household wealth, and connection of a farm household dwelling to the national electricity grid to positively and significantly increased adoption intensity of SIPs and gross farm inputs. This finding highlights the fact that besides government policy such as GFSP towards improving adoption of SIPs and rural development, rural infrastructure and farmer institutions also have a critical role to play.
Secondly, the impact of participation in GFSP on multiple dimensions of food security was examined using propensity score matching without replacement, nearness neighbor matching, inverse probability weighting, and inverse probability weighted regression adjustment. The food availability dimension in terms of average yield of maize was 1.5 ton/Ha, still lower than the potential yield estimate of 5.5 tons/Ha by Ghana’s Ministry of Food and Agriculture. It implies that complementary adoption of technologies is key to bridging this productivity gap. Food access and stability dimensions increased in 2017 compared to 2013. However, the utilization dimension of food security declined, implying that the diversity of food intake may not necessarily be explained by increases in the access dimension of food security in terms of food and total household expenditures. The empirical results indicate that the overall average treatment effect of the GFSP was positive and statistically significant for food availability and food access. The GFSP increased maize yield/Ha between 29 to 34 percent at p < 0.01 among program beneficiaries. For food access, the GFSP increased household consumption expenditure by 37 percent at p < 0.01. The effect of GFSP on the stability dimension of food security was also positive, though weaker statistically against robustness checks. There was, however, negative effect of GFSP on food utilization. The study could not find a straight forward relationship between participation in the GFSP and household food security, as food availability may not necessarily lead to better utilization or nutrition. The less impressive performance of GFSP on utilization and stability dimensions of food security implies that maize growing households who benefited from the program are still food insecure. The positive and significant relationship between the value of agricultural equipment owned and engagement in off-farm enterprise with participation in GFSP may imply that smallholder farmers who may have 2Ha or less of farmland under cultivation but can afford the full cost of fertilizer are benefitting from the subsidy program. The study also found significant and negative correlation between increasing farm size and participation in the subsidy program. It means that farmers with farm sizes greater than 2Ha have not benefitted from the program.
Finally, the study examines the impacts of the complementarity of Integrated Soil Fertility Management (ISFM) technologies on multiple dimensions of food security using the Multinomial Endogenous Switching Regression (MESR). Regarding the complementarity of adoption of ISFM technologies, the results show very low adoption of complementary technologies among maize growing households in Ghana. The empirical results from the MESR showed that all the ISFM choices positively and significantly determined all the dimensions of food security. Joint adoption of the complete ISFM package gives the highest gain in all the dimensions of food security, except the stability dimension. Joint adoption of mineral and organic fertilizers gave the highest gain for achieving household food stability. The implication is that the availability dimension of food security can be met whilst households’ food utilization can still fall below acceptable threshold. Rural development interventions have to focus on the adoption of the complete ISFM package. Otherwise, the piecemeal adoption of any one or two components will not have the desired impact. Input subsidy programs should include organic fertilizers to optimize program benefits. The implication is that policy makers and farmers should see organic and mineral fertilizers as complementarities but never as substitutes as it is currently the case in Ghana. From the multinomial logit results, the study found that household characteristics (e.g., number of years a household spent in school, land ownership, and household head engagement in off-farm work) and institutional factors (such as presence of a mutual aid scheme, access to extension visits, and distance to agriculture office) positively and significantly increased the likelihood of joint adoption of all the ISFM technologies. This finding underscores the need for a dual approach in promoting the adoption of ISFM practices among smallholder farmers by policy makers. This approach should take into account the role of government in increasing the number of extension staff and provision of the necessary infrastructure and logistics and the role of pro-farmer institutions such as farmer credit schemes and cooperatives. Future studies could quantify the potential contribution of ISFM technologies, and broadly, SIPs to the national GDP. Such an effort could add empirical evidence on the pay-offs associated with these technologies for increased adoption by smallholder farmers. Examining these and other related questions employing panel data could result in better understanding of the temporal and spatial dimensions of ISFM practices and their food security impacts and environmental sustainability
Analysing the perceived leadership skills and competencies required by project managers in KwaZulu-Natal Sappi Saiccor.
No full textMasters Degree. University of KwaZulu-Natal, Durban.Leadership is described as the procedure by which a person seeks to persuade other group members to achieve collective goals. Leadership is also considered as a procedure by which individuals bring out the greatest qualities in themselves and others. The aim of the research was to analyse the leadership skills and competencies required for managing projects in KwaZulu-Natal Sappi Saiccor. A quantitative method was done to achieve the research's aims. Convenience sampling method was used to collect data by distributing questionnaires to 72 Sappi Saiccor employees who are working within targeted selected departments. Out of the 72 employees, 55 of them participated on this study. This translated to 76% participance response rate which is regarded to be high enough for validity and reliability of the results. The data received were examined utilising statistical software. The first objective was to determine managers perceptions and the leadership competencies required by project managers in KZN Sappi Saiccor. The research found that there is a statistically significant difference among managers perceptions and leadership competencies required by project managers at KZN Sappi Saiccor. The second objective was to examine managers perceptions and leadership skills required by project managers in KZN Sappi Saiccor. The study found that there is a statistically significant difference among managers perceptions and leadership skills required by project managers in KZN Sappi Saiccor. The third objective was to examine different leadership styles and their effect on successful execution of project in KZN Sappi Saiccor. The study found that there is a statistically significant difference among leadership styles and their effect on successful execution of projects in KZN Sappi Saiccor. The fourth objective was to examine the relationship between leadership skills and competencies and demographic variable. These outcomes demonstrate that just the characteristics of managers’ perceptions (cognitive activation and personalised attention) clarify variations in leadership competencies, alongside cognitive activation being of greater importance. Research suggests that national culture significantly impacts the efficiency of leadership. According to the literature, a leader's skills have a significant impact on worker competencies. Leadership skills influence competencies to varied degrees. Research suggests that leadership skills lead to greater competencies. Research keywords: Leadership skills, competencies, leadership styles, projects management, managers perception
Towards the flourishing of Women Ministers in Evangelical Lutheran church in Southern Africa: an African women’s theological engagement with the lived experiences and systemic realities faced by women ministers in the Evangelical Lutheran church in Southern Africa-South Eastern diocese.
No full textMasters Degree. University of KwaZulu-Natal, Pietermaritzburg.Towards the flourishing of Women Ministers in Evangelical Lutheran Church in Southern Africa: An African Women’s Theological engagement with the lived experiences and systemic realities faced by Women Ministers in the Evangelical Lutheran Church in Southern Africa- South Eastern Diocese. A phenomenological study of lived experiences of women ministers and how they are influenced by systematic patriarchy in their ministry and career growth. The study listened to seven (7) women ministers of ELCSA in their ministerial journey from pre-ordination to ordination and working the field to discover lessons that could be derived from the environmental inhibitors/enhancers of the flourishing of women in ministry. The study looked at processes, acceptance of women and policies and programmes that support flourishing and further sought recommendations from these women on what could be done to enhance women's flourishing. The study used phenomenological approach and held interviews to collect data to understand these lived experiences. Interviews were either face to face or virtual depending on the availability of participants. Engagement with participants enabled the study to draw some conclusions on factors such as heteronormativity, enculturation and absence of gender affirming policies as inhibiting the flourishing of women ministers in ELCSA. The study unveiled an unexpected theme of how sexual reproductive rights as a “sin” has inhibited the flourishing of unmarried young women ministers and remains even a regret for some. Lastly, based on the conclusions drawn, the study brought forth recommendations that may influence or enhance the flourishing of women ministers in ELCSA. The study asserts that should ELCSA leadership engage with gender equity policies, employment policies and clear disciplinary processes that foster a Human Rights advocating space, ELCSA can become an empowering safe space where the flourishing of women ministers can be enhanced and achieved
Advancing precision water management in smallholder sugarcane farming: leveraging unmanned aerial vehicle-based remote sensing and machine learning for evapotranspiration and water stress assessment.
No full textMasters Degree. University of KwaZulu-Natal, Pietermaritzburg.This thesis addresses the imperative of optimising water resource management within smallholder sugarcane cultivation in Swayimane, KwaZulu-Natal, South Africa—a region contending with the dual pressures of escalating food demand and increasingly volatile climatic dynamics. Smallholder farmers are indispensable to advancing food security and socio-economic development, underpinning up to 80% of the region's agricultural output. Nevertheless, their capacity to mitigate food insecurity is hindered by restricted access to vital resources, including reliable water supplies and advanced tools. These limitations necessitate innovative and economically viable strategies to enhance productivity and optimise resource allocation. Precision agriculture (PA) methodologies, supported by cutting-edge technologies such as unmanned aerial vehicles (UAVs), hold promise for smallholder farmers. By enabling data-driven, resource-efficient cultivation practices, UAVs emerge as an instrument to foster sustainable agricultural systems tailored to the unique challenges of these communities.
Sugarcane, a high-value commodity crop, is integral to the socio-economic fabric of smallholder farming communities, substantially contributing to employment and subsequent regional economic advancement. However, the absence of irrigation infrastructure within smallholder systems and escalating water deficits driven by rising temperatures and prolonged dry spells present formidable challenges to sustainable production. This reliance emphasises the need for resource-efficient agronomic strategies that maximise water use while safeguarding yields. By harnessing the potential of PA methodologies, including UAVs equipped with advanced multispectral sensors, farmers can acquire high-resolution insights into crop water dynamics and evapotranspiration processes. To this end, this research pioneers integrating UAV technology with machine learning (ML) to refine water management practices, focusing on enhancing evapotranspiration (ET) estimation and monitoring crop water stress.
Chapter 2 undertakes a bibliometric analysis of UAV applications in precision water management, employing Biblioshiny and VOSviewer to identify key research trends and highlight potential strengths, limitations, and future opportunities. The findings reveal UAVs' potential to address the limitations of traditional ground-based and remote sensing (RS) methods, which are often labour-intensive, expensive, and lack sufficient spatial and temporal resolution for effective water management in smallholder farming systems. UAV technology, driven by advancements in high-resolution data acquisition and the proliferation of cost-effective, open-source processing platforms, offers accessible, scalable solutions tailored to smallholders. While certain factors may moderate their adoption, continuous technological progress and decreasing costs present significant opportunities for UAV applications to enhance policy formulation, strategic planning, and operational decision-making, ultimately strengthening resilience in sustainable water management for smallholders.
Chapter 3 presents an empirical evaluation of vegetation index (VI)-based ET estimation methods. Using data from a smallholder sugarcane field equipped with an eddy covariance (EC) system for ground-truthing, the study assessed five actual ET (ETa) models—ET-NDVI, ET-NDVIscaled, ET-NDVIKc, ET-EVI, and ET-EVI2—alongside an ML-derived crop coefficient (Kc) prediction model correlating in-situ NDVI with Kc values. The EVI2 model demonstrated superior performance, achieving moderate to strong correlation (R² = 0.63) with lower Root Mean Square Error (RMSE = 0.67) and Mean Absolute Error (MAE = 0.52) compared to competing models. EVI2's resilience against NDVI saturation—a persistent challenge in mature sugarcane—translates to improved water use assessment, while reduced reliance on extensive in-situ data enhances its scalability for smallholder systems. Furthermore, high-resolution ETa maps derived from these models offer potential insights for optimising irrigation and improving productivity in resource-limited agricultural contexts.
Chapter 4 presents a novel ML-based predictive model for the Normalised Difference Water Index (NDWI), utilising correlations with structural VIs (SVIs) from UAV and Sentinel-2 data. The Random Forest (RF) ensemble model achieves exceptional accuracy (R² = 0.95, RMSE = 0.03, MAE = 0.02), offering a precise and efficient tool for monitoring sugarcane water stress. Validated against ETa and the Water Deficit Index (WDI), the model confirms NDWI's reliability as a proxy for assessing sugarcane water status. A Principal Component Analysis (PCA) reveals complex interactions between NDWI, SVIs, and physiological parameters, further enhancing insights into sugarcane water status. Additionally, temporal analysis highlights NDWI's responsiveness to rainfall, with marked fluctuations pinpointing critical stress periods. By minimising dependence on in-situ measurements, the model offers a scalable, cost-effective solution tailored to the needs of resource-constrained smallholder farmers.
In conclusion, this thesis advances PA by integrating UAV technology and ML to revolutionise water management in smallholder sugarcane farming. The VI-based ET estimation models and NDWI prediction framework deliver customised, high-resolution insights to optimise irrigation and enhance water efficiency during critical growth phases. Beyond showcasing these innovations, the study emphasises the necessity of capacity-building initiatives and user-friendly tools to enable farmer adoption, addressing climatic and socio-economic constraints. This work establishes a foundation for scalable, context-specific solutions despite its limited scope. Future research should prioritise decision support systems integrating UAV data and predictive models for real-time water stress monitoring and adaptive irrigation. By empowering smallholders, this study contributes to resilient agricultural systems, enhanced food security, and sustainable sugarcane production, laying the groundwork for global efforts against water scarcity and climate variability
Probing sexual and reproductiveh health (SRH) services: experiences of women at Umkhambathini eNkanyezini, KZN-South Africa.
No full textDoctoral Degree. University of KwaZulu-Natal, Pietermaritzburg.This qualitative study contributes to feminist anthropology, specifically the anthropology of women, by exploring the sexual and reproductive health (SRH) experiences of rural women in uMkhambathini, eNkanyezini, KwaZulu-Natal, South Africa.
The study problematizes the higher mortality rates of rural women compared to men in this village, highlighting significant health disparities. Feminist anthropology addresses the interconnected challenges women face in accessing healthcare and proposes meaningful solutions. The study is framed by three theoretical perspectives: Social Constructivism, Critical Medical Anthropology, and Gender Theory. Purposive and snowball sampling methods were used to select thirty (30) participants, with data collected through five focus groups, each comprising six women.
The findings underscore the continued marginalisation of rural women in uMkhambathini, impeding the realisation of South Africa's National Development Plan Vision 2030. These women remain unable to fully access Basic Human Rights as enshrined in the South African Constitution (No.108 of 1996) and international frameworks such as the Sustainable Development Goals (SDGs), which advocate for sexual and reproductive rights. Data analysis reveals that structural barriers, including education levels and family size, significantly hinder their ability to access and utilise SRH services. Furthermore, rural healthcare facilities in uMkhambathini are underresourced and geographically isolated, exacerbating healthcare exclusion due to inadequate resources and limited government intervention. The study introduces the Framework for Localised Reproductive Health and Support Structures (FLRHSS), which aims to accelerate the provision of SRH services for the benefit of rural women in uMkhambathini. The findings also reveal inconsistencies and a lack of clarity regarding the age of consent for HIV and SRH services in high-burden areas like eNkanyezini, particularly concerning oral PrEP. The study recommends prioritising rural women in SRH programs and expediting the implementation of the National Health Insurance (NHI) system to address structural, economic, and geographic barriers. Ensuring the availability of essential medical technologies and products is crucial for enabling healthcare workers to deliver effective services. Additionally, community-based education programs targeting women and mothers are vital for dismantling systemic barriers to SRH access. This research underscores the need for a more inclusive and equitable approach to SRH services that addresses the unique challenges faced by rural women in South Africa. It also calls for future research to explore the SRH needs of women with disabilities, further advancing a comprehensive understanding of reproductive health disparities in rural contexts
Late mid-summer dry-spells and planting dates of maize in the western maize-growing region of South Africa.
No full textMasters Degree. University of KwaZulu-Natal, Pietermaritzburg.South Africa experiences a climate characterised by arid conditions and significant variability in annual rainfall. This exerts a severe impact on water resources, agriculture, and the socio-economic sector of the region. Drought is a natural occurrence known for sustained below-average precipitation over a specified period, and it is a well-documented aspect of a region's climate variability. Existing research has predominantly focused on drought occurrence, impact, intensity, and duration, primarily on seasonal and annual scales. This study deviates by emphasising the importance of recognising mid-summer droughts in the agricultural sector, where the timing and severity of dry-spell periods hold greater significance than overall seasonal rainfall deficits. Mid-summer droughts, occurring typically from December to January in the summer rainfall regions, coincide with a shift in atmospheric circulation from baroclinic to barotropic. This shift is dominated by tropical systems and is particularly critical as the timing aligns with the water stress-sensitive flowering stage of summer crops like maize and sorghum. Given the potential detrimental effect on crop yield, especially maize, there is a need to investigate and understand the patterns associated with these events. By delving into the specifics of mid-summer droughts, this research aimed to contribute valuable insights to aid and mitigate the adverse impacts on agricultural productivity in South Africa. However, in this study, the late-midsummer period, which spans from mid-January to the end of February is of particular importance. This is because maize is planted later in the western region of maize production than it is in the temperate and cooler eastern maize production regions. Therefore, dry-spells, which occur around the mid-January to the end of February period, normally correspond with maize's flowering cycle in the western maize growing regions of South Africa. However, it is worth noting that due to shifting planting dates, the flowering stage may occur later and remain unaffected by the phenomenon. During this sensitive stage of the growth cycle, even a few days without rain could result in lower crop production. The Markov chain model analysed the probability of initial and conditional dry-spell pentads. In addition, the Mann-Kendall monotonic trend test and Sen's slope estimator were performed to check the direction and magnitude of dry-spell trends. It consistently revealed the impact of dry-spells throughout the mid-January to late February period, the most critical phase in the flowering of maize for the western maize-producing region. Although most districts showed a downward trend in the occurrences of dry-spells, this was not statistically significant. Sen's slope estimator further supported a reduction in the magnitude of dry spells over the study period. This research thus provides important information to farmers by enhancing their understanding of shifting risk profiles associated with dryspells. Furthermore, utilising AquaCrop simulation simulations, the study explored the influence of planting dates on maize yield in the western maize growing region. The latest simulated planting date of 20 December was found to result in the best maize yields across most Rainfall Districts. However, certain districts with low dry-spell frequencies experienced lower average yields compared to mediumfrequency seasons, potentially linked to heavy rainfall distribution during the flowering stage of maize. The analysis of the rainfall data showed that during some low frequency dry-spell seasons, extreme rainfall events occurred. These extreme rainfall events may have led to waterlogging issues, resulting in a reduction in crop yield below the typical maize production levels. In conclusion, the AquaCrop model provided reliable and realistic outputs, with crop yields aligning well with observed rainfall patterns. A two-way ANOVA test indicated that there is a statistical significance between maize yield and planting dates in most of the Rainfall Districts, with the planting date of 20 December simulating the best maize yields compared to the other planting dates in most of the Rainfall Districts. Thus, the period after the 20th of December has higher crop yield. This is because crops planted around this date will flower outside the late midsummer period, and as a result, they will not be affected by the dry spells. It is recommended that future research should focus on examining the impacts of dry spells on different maize varieties and assessing the effects of climate change on dry spell occurrence
Evaluation of mycoparasitic fungi as potential biological control agents of wattle rust (Uromycladium acaciae)
No full textMasters Degree. University of KwaZulu-Natal, PietermaritzburgUromycladium acaciae (Cooke) P. Syd. & Syd., the causative agent of wattle rust, is an economically significant pathogen affecting black wattle (Acacia mearnsii De Wild) in the Republic of South Africa (RSA). Initial symptoms are brown powdery pustules on petioles, stems, and leaves which further develop into matting of leaves and pinnules, and rachis malformation. In severe cases, infection results in stunting of seedlings and mortality of young trees. Yield losses of up to 40% have been reported. The current control measures for wattle rust consist of azoxystrobin and triazole-based fungicides and the deployment of resistant or tolerant lines of A. mearnsii. However, due to undesirable environmental effects posed by fungicides, the substantial costs involved with both fungicide usage and the deployment of tolerant clones of A. mearnsii and increasing regulations around the use of fungicides in commercial forestry, there is a need for alternative control methods for wattle rust. The use of biological control presents a cost-effective and environmentally friendly alternative method for the management of wattle rust. Several mycoparasites of various rust diseases have been evaluated on different rust diseases as potential biological control agents. In this study, the mycoparasites Sphaerellopsis filum (Biv.- Bern. ex Fr.) Sutton [=Darluca filum (Biv.-Bern. ex Fr.) Berk.] and Akanthomyces uredinophilus Manfrino et al. were evaluated for biocontrol efficacy on wattle rust using an in vitro detached leaf assay. Leaves of black wattle infected with U. acaciae were collected from a local commercial plantation in Richmond, KwaZulu-Natal, South Africa. Rust-infected leaves were sprayed with conidial suspensions of 1 g.L-1 of S. filum (5.8x108 conidia.ml-1) and A. uredinophilus (1x106 conidia.ml-1) and incubated in plastic containers containing moist paper towels to create conditions of high humidity. Colonisation of rust pustules by A. uredinophilus and S. filum was assessed under a light microscope and a percentage colonisation for each treatment was estimated at four weeks post-inoculation. Colonised leaves were also viewed under an environmental scanning electron microscope (ESEM) to examine the interaction between the mycoparasitic fungi and U. acaciae. At four weeks post inoculation, A. uredinophilus and S. filum were able to colonise 41% and 44% of rust pustules, respectively. Under the ESEM, S. filum and A. uredinophilus demonstrated mycoparasitic activity on the teliospores of U. acaciae. Hyphae of S. filum and A. uredinophilus coiled around and punctured rust teliospores, causing them to rupture and deflate. Overall, conidia of both S. filum and A. uredinophilus were able to colonise and mycoparasitize U. acaciae teliospores. Optimal Integrated Pest Management (IPM) for disease suppression requires the seamless and coordinated integration of multiple compatible control strategies. Therefore, any biological agents that may be considered for use to suppress a disease should be compatible with the range of agrochemicals and adjuvants that are being used on the crop of interest, in order for the management strategy to be effective. To this end, the compatibility of two isolates of mycoparasitic fungi (Sphaerellopsis filum and Akanthomyces uredinophilus) and a commercial insect-pathogenic fungus (Beauveria bassiana, Eco-Bb®) with an insecticide (deltamethrin) and an adjuvant (Break-thru®) was evaluated. The experiment utilized an amended bioassay method with S. filum, A. uredinophilus, and B. bassiana being cultured on potato dextrose agar (PDA) amended with 250 μl.L-1, 125 μl.L-1 , and 500 μl.L-1 of Break-thru® , or amended with 1 ml.L-1, 0.5 ml.L-1 and 2 ml.L-1 of deltamethrin. Unamended media served as a negative control, whilst media amended with the commercial rust fungicide Amistar Top® served as a positive control. After three weeks, radial growth was measured from the centre of the fungal colony, and a percentage inhibition efficiency (IE) of Breakthru ®/ deltamethrin on the growth of the biological control agent was calculated. There was no significant inhibition in any of the biological agents by either Break-thru® or deltamethrin at all dosages tested. Therefore, S. filum, A. uredinophilus and B. bassiana are compatible with the insecticide (deltamethrin) and the adjuvant (Breakthru
®), and they could be combined in an integrated control program. Further evaluation of the two mycoparasitic fungi as potential biological control agents of wattle rust were undertaken in nursery pot trials. Pot Trial One investigated the biological control efficacy of mycoparasitic strains of S. filum and A. uredinophilus for control of wattle rust on three wattle varieties. Rust-infected cuttings of varieties PSO14, FW54 and SP644 were treated with S. filum and A. uredinophilus every two weeks for 12 weeks. They were also evaluated for rust levels every two weeks, as percentage leaf area infected. Experimental controls included a fungicide control (positive control) and untreated rust control (negative control). Bi-weekly applications of S. filum significantly reduced (p< 0.001) rust disease progression. Although applications with A. uredinophilus did reduce disease progression, it did not produce a significant reduction compared to the untreated rust control. After six and nine weeks of bi-weekly treatment applications, characteristic white mycelial growth of A. uredinophilus and S. filum, respectively, were observed on rust pustules. Characteristic spore morphology that resembled that of S. filum and A. uredinophilus was confirmed after re-isolation. There was no significant difference (p= 0.09605) between the wattle varieties in their response to the treatments. Overall, both S. filum and A. uredinophilus have the potential to control wattle rust.
In Pot Trial Two, the optimal dosage and application frequency of S. filum and A. uredinophilus was evaluated on the FW54 (susceptible, frost tolerant) commercial wattle variety. Conidial suspensions of the mycoparasitic strains were prepared at dosages of 1 2 x, 1x and 2x at a quantity of 5x105 conidia.ml-1, 1x106 conidia.ml-1, and 2x106 conidia.ml-1 of A. uredinophilus, and 0.5 gram, 1 gram and 2 gram.L-1 of S. filum (5.8 x 108 conidia.ml-1). The conidial suspensions were sprayed at three frequencies which were once-off, bi-weekly (every two weeks), and monthly. Prior to every biweekly spray treatment, percentage rust severity (0 to 100%) was scored for all treatment frequencies on the fully expanded leaves directly below the new flush. The percentage rust severity was used to calculate the area under disease progress curve (AUDPC). For S. filum and A. uredinophilus, dosage and frequency of application had no significant interaction. All treatments reduced wattle rust relative to the untreated control treatment. Notably, the bi-weekly treatment with a 2x dosage of A. uredinophilus resulted in the least amount of rust disease, which was not significantly different to that of the fungicide treated control.
In Pot Trial Three, the use of silicon fertilization in conjunction with A. uredinophilus (the best performing biocontrol treatment as identified in Pot Trial Two) for optimal control of wattle rust was evaluated. A spray application of 2x106 conidia.ml-1 of A. uredinophilus was combined with silicon fertilization at concentrations of 100, 200, and 400 mg.L-1 for evaluation of the control of wattle rust on the commercial wattle variety FW54. The A. uredinophilus spore suspension was sprayed bi-weekly (every two weeks), and treated seedlings were drenched every week with 10L of water containing silicon at 100, 200, and 400 mg L-1. Prior to every bi-weekly A. uredinophilus spray treatment, percentage rust severity (0 to 100%) was scored on the fully expanded leaves directly below the new flush. Experimental control treatments included a fungicide control (positive control, Amistar® Top, Syngenta) and an untreated rust control (negative control). At 16 weeks, leaf samples were taken from seedlings to evaluate the uptake and distribution of silicon using Field Emission Gun-Environmental Scanning Electron Microscopy (FEG-ESEM) and Energy Dispersive X-ray Spectroscopy (EDX). All treatments reduced wattle rust relative to the untreated control treatment. Treatment with A. uredinophilus + 400mg.L-1, silicon resulted in the least amount of rust disease. However, the A. uredinophilus + 0mg.L-1 silicon treatment also produced a significant reduction in rust. The EDX spectra and mapping showed that silicon was not taken up by treated plants. The combined application of A. uredinophilus and silicon fertilization did not result in the enhanced control of wattle rust because wattle appears not to take up silicon as a micronutrient. The overall results of this study suggest that both mycoparasites can be used as biological control agents for wattle rust. Bi-weekly applications of A. uredinophilus at 2x106 conidia.ml-1 was the best performing biocontrol treatment in these pot trials. However, it is unknown whether the nursery application of A. uredinophilus would yield sufficient fungal inoculum to control wattle rust under field conditions. Therefore, field trials should be implemented to establish the biocontrol efficacy of S. filum and A. uredinophilus under field conditions
Morphological diversity, heritability, and selection of the first F7 improved Bambara groundnut (Vigna subterranea L. Verdc) evaluated in South Africa.
No full textMasters Degree. University of KwaZulu-Natal, PietermaritzburgBambara groundnut (Vigna subterranea L. Verdc) is an underutilised legume crop that can improve food and nutrition security, especially in low-input farming systems. The specific objectives of the study were: (i) to evaluate the agro-morphological diversity of Bambara groundnut (BGN) recombinant inbred lines (RILs) using quantitative and qualitative traits, (ii) to determine genetic variance components among BGN RILs to guide future selection. The first study assessed the genetic diversity present among BGN genotypes using agro-morphological traits. Fifty-four BGN genotypes comprising 44 RILs developed from a cross between single genotype Tiga Nicuru (maternal) and Dip-C (paternal) lines and ten local checks were evaluated in three environments in the KwaZulu Natal province of South Africa. The genotypes were laid out using 6 x 18 alpha lattice block design replicated twice. The combined analysis of variance (ANOVA) showed significant (P < 0.01) difference among the genotypes for most of the agro-morphological traits, except for days to 50% emergence (DTE), days to 50% flowering (DTF), and plant spread (PS). The genotype by environment interaction effects were highly significant (P < 0.001) for seed length (SL), seed width (SW), grain yield (GY), unshelled grain yield (UGY), grain yield per plant (GYPP) and shelling percentage (SHLP). Principal component analysis (PCA) showed that the first four principal components accounted for 79% of the total phenotypic variance observed. Hierarchical cluster analysis assigned the 54 BGN genotypes into six clusters. The second study assessed genetic variance parameters among the 44 RILs and ten local checks. Germination percentage recorded the highest broad-sense heritability (H2) estimate of 65%, while days to 50% flowering recorded the highest H2 (65%).GY recorded the highest phenotypic coefficient of variation (69.4%), genotypic coefficient of variance (44.8%), and genetic advance (59.5%). The best linear unbiased prediction (BLUP) estimates revealed that the genotypes P3, G23, G1, G8 and LL4 were superior and high yielding. These genotypes should be recommended for further multilocational evaluations
Modeling economic growth for Nigeria using robust statistical models.
No full textDoctoral Degree. University of KwaZulu-Natal, Durban.Economic growth is one of the most important goals of macroeconomic policy-making, but measuring it is not easy. This study aimed at measuring economic growth for Nigeria using robust statistical models. In this study, Gross Domestic Product (RGDP) is used as a proxy for economic growth and is modelled using selected predictors, namely internal debt (INDT), external debt (EXDT), interest rate (RINR), an exchange rate (REXR), and trade openness (OPEN). Quarterly RGDP index collected from the Central Bank of Nigeria for the period 1986 to 2022 was used in this study. Exploratory data analysis (EDA) revealed the linear relationship between the RGDP and the predictors. EDA also revealed the presence of multicollinearity and outliers in the predictors. In the presence of outlier and multicollinearity, this study utilizes the ridge regression, robust principal component regression, partial least square regression, average centered penalized regression, gaussian process regression and the coupler FMKL-GLD quantile regression. The performance and the efficiency of the adopted methods were evaluated using forecasting accuracy metrics, namely the root mean square error (RMSE), mean absolute error (MAE) and mean absolute percentage error (MAPE). In using robust PCR, it can be asserted that the robust principal component regression (M-estimator) technique was an efficient and optimal technique for predicting RGDP. Specifically, PC1 and PC2 account for 35.39% and 22.15% in RGDP. In PLS, non-cross-validated and cross-validated PLS selection methods were used. Thus, 91.5% of the variance in economic growth drivers were explained by the five components generated and selected from the non-cross-validated PLS method. While, 72.6% of the variance in economic growth drivers were explained by the two components generated and selected from the cross-validated PLS method. Hence, after the cross-validation and extraction, the first and second components were efficient and optimally predicted 63.1% and 18.4% economic growth. In the average centered penalized regression model, the performance of the LASSO, ridge and elastic net techniques were compared. Using the least value of the forecasting metric values, the LASSO-average centered penalized regression was robust. The result of the best-performing average-centered penalized regression model indicated that INDT, RINR, REXR and OPEN positively contributed to the RGDP by 4.27%, 0.40%, 0.49% and 0.52% respectively. while, EXDT decreases RGDP by 0.97%. In the fitted gaussian process regression, the main effect of INDT, EXDT, RINR, REXR and OPEN for predicting RGDP were 38.30%, 12.20%, 1.10%, 2.00%, and 1.20% respectively which were increased after the independent re-sampling to 56.30%, 6.90%, 3.10%, 2.80%, and 2.10% for predicting RGDP. The estimated performance of FMKL-GLD quantile model techniques revealed that FMKL-GLD 50Q model was efficient for examining and predicting economic growth in Nigeria. Thus, INDT, RINR, REXR and OPEN positive contribution to RGDP were 17.94%, 29.42%, 7.99% and 145.10% respectively. Meanwhile, RGDP, as a result of EXDT was reduced by 3.92%. Therefore, government and policymakers should properly harness the benefit of trade openness to engender international patronage for economic growth. Also, coupler FMKL-GLD 50Q quantile regression technique and gaussian process regression method are the most efficient predictive statistical methods to deal with multicollinearity and outliers. However, Nigeria’s economy had gone through various seasons, thus, a further study can be done to investigate structural breaks and propose appropriate model(s).Author's Keywords : Keywords: economic growth, multicollinearity, outliers, robust principal component regression, FMKL-GLD quantile regression and Gaussian process regression metho