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Mucuna pruriens L. (DC) and Arachis hypogaea (L.) enhance soil biological and chemical properties of nutrient-deficient small-scale sugarcane soils.
(2025) Khwela, Sikhanyiso Bright.; Magadlela, Anathi.; Ramdhani, Syd.
Most of the rural population in South Africa rely on agriculture for food security and livelihood. In KwaZulu-Natal, sugarcane production plays a significant role in the livelihoods of smallscale farmers in rural areas. However, there has been a decline in sugarcane productivity and yield due to soil-health-related problems caused by long-term monoculture and excessive chemical fertilizer use. Legume cover cropping is an attractive and sustainable alternative to reduce overreliance on synthetic nitrogen (N) fertilizers since legumes increase soil N levels through symbiotic N fixation. Mucuna pruriens L. (DC) and Arachis hypogaea L. have been reported to fix approximately 34-242 kg N ha-1 and 150-200 kg N ha-1, respectively.
Furthermore, these legume species have been reported to provide ecosystem services such as nutrient cycling, weed suppression, soil erosion control, increased organic matter, and microbial diversity. Therefore, this study investigated the effects of cultivating M. pruriens and A. hypogaea on the soil chemical characteristics, bacterial community composition, and enzyme activities of five different acidic and nutrient-deficient sugarcane plantation soils in KwaZulu-Natal, South Africa. Additionally, the study evaluated the N-source preference, biomass accumulation, and plant nutrition of M. pruriens and A. hypogaea growing in these acidic and nutrient-deficient sugarcane soils. Post-harvesting, the soil pH increased across all study sites for both legume species. Both M. pruriens and A. hypogaea sanctioned for Ncycling, N-fixing, and P solubilizing bacteria with the dominant strains belonging to the Burkholderia and Pseudomonas genera. The increase in P solubilizing bacteria, alkaline and acid phosphatase activity assisted with the demands of biological N fixation, allowing M. pruriens and A. hypogaea to fix 26-58% and 40-70% of N from the atmosphere, respectively.
Overall, the findings of this study showed that M. pruriens and A. hypogaea contribute to soil health improvement by reducing soil acidity and increasing the diversity of nutrient-cycling bacteria and their associated enzyme activities in small-scale sugarcane soils.
The effects of thermal stress on the physiology of two high-latitude corals from the environmentally variable intertidal and moderate subtidal habitats.
(2025) Boodraj, Prishani Devi.; Glasson, David.; Vosloo, Dalene.
Corals are of great ecological and economic importance; however, they are increasingly threatened by mass bleaching events caused by ocean warming, which has become more frequent and is predicted to increase in frequency and severity in the coming years. The degree of coral bleaching, recoverability, and mortality is highly variable and considered to be affected by the coral’s physiological and antioxidant capacity and the thermal regimes they experience. These mechanisms are still poorly understood and need to be investigated in different coral species from varying environmental regimes when exposed to prolonged thermal stress and during recovery to better inform conservation measures. Coral communities found on the subtropical East Coast of South Africa can be defined as ‘extreme’ due to the sub-optimum environmental conditions experienced especially in intertidal habitats and ‘marginal’ since, ecologically, they are not true accretive reefs. Climate change has not caused severe bleaching in corals of this region, but the physiological mechanisms that influence their thermal resilience/susceptibility are yet to be investigated. Therefore, this thesis examined the thermal resilience/susceptibility of Anomastraea irregularis (massive morphology) and Pocillopora verrucosa (branching morphology) from the intertidal and subtidal zones of the understudied rocky shores of Treasure Beach, east coast KwaZulu-Natal province, South Africa using both laboratory and field studies. The intertidal pools in this region are highly dynamic, with large summer daytime fluctuations of more than 10°C at spring tide while the subtidal zone is notably more environmentally stable. These corals were maintained in closed recirculating aquaria and exposed to two constant thermal stress conditions (control: 26°C, thermal stress treatments: 28°C and 30°C) for three months and then were maintained at control conditions for two months to monitor recovery. Respiration, photosynthetic, and growth rates were measured monthly. The Symbiodiniaceae density, chlorophyll-a concentration, chlorophyll-a concentration per symbiont cell, lipid concentration, protein concentration, antioxidant enzyme activity (superoxide dismutase, catalase, glutathione peroxidase, glutathione s-transferase), and caspase 3 activity were analysed at the start and end of the thermal stress as well as at the end of the recovery period. The thermal stress treatments induced bleaching (significant decrease in Symbiodiniaceae density and chlorophyll-a concentrations) in both species from both habitats with associated significant decrease in photosynthetic and growth rates. Increased oxidative stress was also evident with the increased superoxide dismutase, catalase, glutathione peroxidase, and caspase 3 activity in fragments in both thermal stress treatments at the start and end of thermal stress and at the end of recovery.
There were inherent physiological differences between the species and habitat that were maintained throughout the experiment, highlighting that variable thermal regimes and coral species can influence coral resilience to thermal stress. The intertidal corals were more resilient (less bleaching and fewer deaths) than their subtidal conspecifics, and A. irregularis appeared more resilient than P. verrucosa in both thermal stress treatments. The intertidal corals could lower their respiration rates to that of the control rates by the end of thermal stress and maintained higher Symbiodiniaceae densities, chlorophyll-a, and lipid concentrations than their= subtidal conspecifics throughout the study. Resilience of A. irregularis may be a result of its thicker tissue, which allowed higher Symbiodiniaceae density and lipid concentrations and lower P:R ratios demonstrative of a more heterotrophic nature. Overall, higher protein concentrations and lower antioxidant enzyme activities (superoxide dismutase, catalase, and glutathione peroxidase) were evident in intertidal fragments than subtidal fragments and A. irregularis than P. verrucosa when thermally stressed. The higher protein concentrations may have facilitated the corals’ physiological processes that made them more resilient to prolonged thermal stress. Therefore, these corals may have had lower antioxidant activities because of less oxidative stress. The results indicated much higher antioxidant activity in susceptible corals, suggesting that oxidative stress may be responsible for higher bleaching and mortalities. The photosynthetic and growth rates, Symbiodiniaceae density, chlorophyll-a concentration, and lipid concentration of both species from both habitats did not fully recover two months after thermal stress. Similarly, the antioxidant enzyme activities (superoxide dismutase, catalase, glutathione peroxidase), and caspase 3 activities of both species from both habitats did not decrease to control levels at the end of recovery, indicating that a longer period would be required for full recovery of the biochemical and physiological pathways of these corals. This has implications for coral reef recovery trajectories in situ since less time between mass bleaching events is predicted in the near future.
Field studies are important for validating the physiological responses found during laboratory studies since the static nature of laboratory experiments cannot account for the dynamic environmental conditions corals encounter in situ. A pilot study was conducted to determine if the ‘flexi-chamber’ and photogrammetry could be used to track respiration, photosynthesis, and growth of A. irregularis and P. verrucosa fragments (3 cm > 4 cm) in the intertidal and subtidal habitats in Park Rynie, east coast KwaZulu-Natal province, South Africa. This study found that the two methods could be optimised to effectively measure the physiological processes of coral fragments in both habitats at relatively low cost and low complexity.
To understand the physiological responses of these species when exposed to thermal stress in their natural habitats an in-situ experiment at Treasure Beach was conducted during the warmer austral spring and summer months where fragments of both species were reciprocally transplanted between the two habitats. Controls were established by placing fragments in their original habitats. Respiration, photosynthesis, growth rates, and coral health scores were measured monthly for six months. The physiological rates were measured using the optimised methods that were obtained during the pilot study. The Symbiodiniaceae density, chlorophyll-a concentration, chlorophyll-a concentration per symbiont cell, and lipid concentration were also
analysed at the start and end of the study. Similar to the laboratory results, differential physiological responses between species and habitat were evident in response to the reciprocal transplantation. Intertidal A. irregularis and P. verrucosa transplanted into the subtidal habitat showed potential acclimation to the subtidal habitat. These fragments were able to adjust their P:R ratios and maintain higher Symbiodiniaceae cell density, Symbiodiniaceae chlorophyll-a concentration, and Symbiodiniaceae chlorophyll-a concentration per cell, and lipid content thereby experiencing less bleaching and mortalities. Anomastraea irregularis appeared more physiologically plastic (altering respiration rates and maintaining higher Symbiodiniaceae cell density and lipid concentration) and therefore more tolerant (less bleaching and mortalities) than P. verrucosa to the changes in environmental conditions.
The laboratory and field results add to the limited knowledge of how high-latitude corals of different species and from habitats of differing environmental regimes react physiologically to long-term thermal stress. The results are promising since these resilient corals may be used in
future conservation initiatives. The results of this thesis show the ability of some coral species to acclimatise and/or adapt to different environmental conditions, however, the potential for these corals to acclimatise/adapt to global climate change related stressors still warrants further
investigation especially since several other stressors are also impacting reef systems.
Physiological and genotypic analyses of the African leafy vegetable, Amaranthus dubius, in response to environmental stresses and cryopreservation.
(2025) Haripershad, Ashiq.; Shaik, Shakira.
Africa’s population is predicted to double by 2050. However, the current population’s dietary demand exceeds the agricultural output capacity of arable land and irrigable water. This issue is further exacerbated by the climate crisis, causing unpredictable rainfall and weather patterns and influencing
soil quality and water supply. Identifying under-utilised crops that are resistant to water-deficit, soil salinity, and high temperatures can therefore mitigate some of these challenges to secure a sustainable food supply. Furthermore, long-term preservation of identified resilient genotypes is
necessary to safeguard germplasm for future research and use. It is, therefore, also necessary to investigate post-storage plant growth and development to determine viability retention and true-totype genetic fidelity.
Amaranthus dubius, an under-utilised African leafy vegetable, thrives in southern Africa and is a nutritious food source containing many essential vitamins, minerals, and nutrients. This annual shrub can also tolerate environmental stresses and remains resilient on marginal lands. However,
phenotypic variations observed in wild-type populations, including altered growth rates and biomass partitioning, result in reduced nutrient concentrations and yield, unpredictable quality, and overall agricultural inefficiency, hindering propagation and cultivation. Furthermore, the underlying genetic regulation of these stress responses has not been investigated, representing a missing step towards improving crop resilience, resource-use efficiency, and developing propagation strategies. This study aimed to elucidate the growth, physiological and genetic responses of A. dubius to waterdeficit, soil salinity, high-temperature, and preservation stresses, thereby identifying superior, resilient genotypes. Phenotypic responses were quantified by individually exposing A. dubius seedlings to each stress and measuring various growth and physiological parameters. Genetic expression was measured by quantifying mRNA transcripts of stress-responsive genes. This data was used to identify and clonally propagate superior genotypes, through cuttings and in vitro propagation, to conserve desired traits and increase scalability for greater agricultural capacity.
Multiple stress-tolerant specimens of A. dubius were identified by measuring biomass, shoot height, leaf area, water pressure potential, electrical conductivity, and contents of total chlorophyll, proline, and protein. Proteins were characterised in water-deficit and heat stress tolerant genotypes. The
expression of putative Na+/H+ antiporter transcripts was quantified using degenerately-primed realtime qPCR, revealing a mechanism of ionic stress tolerance whereby toxic solutes were increasingly compartmentalised in roots rather than foliar tissues under salinity stress. Quantification of waterdeficit, high-temperature and cryopreservation-responsive transcripts requires further optimisation. Nevertheless, this research produced water-deficit, salinity, high-temperature and preservationtolerant clonal genotypes of A. dubius, aiding the struggle for food security in southern Africa. This
work culminated in the expansion of indigenous knowledge and facilitates future studies regarding gene identification, sequencing, and the possible development of transgenic crops to withstand achanging climate.
Preparedness of the public sector for the implementation of the access to information act (2016) in Kenya.
(2019) Kabata, Victor Kanganga.; Garaba, Francis.
Access to public information impacts on all spheres of human development. That is, economic, political, social, cultural among others. Access to information laws seek to facilitate citizen access to public information. This is premised on the understanding that public information is collected and collated using public resources. In essence, public information belongs to citizens with the government only playing a custodial role. As such, enactment and effective implementation of ATI laws enables citizens to participate in public policy formulation, decision-making and delivery of public services thus fostering good governance. This study sought to investigate the capacity of public bodies in Kenya to implement the Access to Information (ATI) Act 2016 with a view to providing an implementation roadmap. The study sought to address the following research questions: What is the extent of leadership and political will for institutionalization and implementation of the ATI regime in Kenya? What is the level of awareness of duty bearers of their ATI responsibilities as stipulated in the Act? What systems, processes and structures are in place in public bodies for the implementation of the ATI Act 2016? What is the current records management regime and its impact on the implementation of the ATI Act and What recommendations for improvement can be made from the areas of strengths or weaknesses identified? A complement of theoretical models and concept underpinned the study thus facilitating the understanding of the multifaceted phenomenon of access to information. These were the United Kingdom (UK), Department of Constitutional Affairs (DCA), Model Action Plan (MAP) 2003; the Carter Centre’s, Access to Information (ATI), Implementation Assessment Tool (IAT); the concept of ‘Meaningful engagement’ and the records continuum model. Literature was reviewed based on the themes generated from the research questions, the supporting models and broader areas of the study. The study adopted a pragmatic paradigm using a mixed methods approach that had a bias towards a quantitative dominant, complemented by a qualitative follow up and triangulation during data collection. Survey research design was used to collect data using questionnaires, semi-structured interviews, observation checklists and document review. Participants in this study included Public Communication Officers; Records managers; Registry clerks; the Ombudsman; Director of Public Communication; Director of Administration in ministries/department and the Director National Archives. A census approach was adopted with all the 22 ministries that make up the public sector in Kenya being surveyed. Reliability and validity of the instruments was determined through triangulation, peer debriefing, member checking and Cronbach alpha. Quantitative data was coded and analysed through Statistical Package for Social Sciences (SPSS) and presented in form of tables, graphs and figures where applicable. On the other hand, qualitative data was analysed thematically and presented through narrative description. The findings of the study revealed that Kenya’s leadership had taken certain actions that demonstrated preparedness and willingness to implement the ATI Act 2016. However, more needs to be done to spearhead the ATI agenda. In particular, the crafting of a legislative framework that supports openness; committing funds to actualize ATI programmes; formulating an ATI policy framework and deployment of trained personnel to handle ATI requests. Further, the study established that government ministries had only undertaken short-term preparations to create awareness among public officers on their ATI responsibilities as stipulated in the Act. However, long-term measures that would entrench a culture of openness among public officers were yet to be undertaken. These include: formulation of an ATI training framework; prioritizing ATI capacity building across the public service and rallying senior officers to spearhead the openness agenda. In relation to the systems, processes and structures in place for ATI implementation, the study revealed that government ministries had put in place informal mechanisms to facilitate handling of ATI requests. In particular, although the Ombudsman had issued instructions to public entities on handling of ATI requests, these instructions were not anchored on an elaborate legal framework thus prone to litigation. Lastly, the study revealed that the existing records management regime largely facilitated the implementation of the ATI Act 2016. However, the study noted that more needed to be done to harmonize the ATI legislation and the Public Archives Act; provide adequate and appropriate records storage space; develop systems and standards for e-records management and build capacity for e-records management. The study therefore concluded that government ministries in Kenya had only undertaken short-term measures towards implementation of the ATI Act 2016. In line with its purpose, the study proposed a raft of long-term measures that would ensure effective implementation of the ATI Act 2016.
A critical evaluation of some of the unintended consequences of the mandatory minimum sentencing legislation in South Africa.
(2024) Nkosi, Banele Prince.; Khumalo, Khulekani.
The Criminal Law Amendment Act 105 of 19971 (the Act) requires the imposition of mandatory minimum penalties for specific criminal offences. However, it also allows the presiding officer of the court to depart where is it determined that substantial and compelling circumstances are present. This research seeks to evaluate the diverging interpretations of substantial and compelling circumstances by our courts as an unintended consequence of the mandatory minimum sentencing scheme. Although the legislature has not defined substantial and compelling circumstances, the case of S v Malgas2 provided guidelines that can be used by courts whenever faced with the question of what are substantial and compelling circumstances. Despite the guidelines provided, some cases still show uncertainty regarding this phrase and some judgements tend to completely disregard the importance of the constitutional considerations of proportionality and the need to still consider the traditional sentencing principles, this is an unintended consequence of the Act owing to the lack of clarity regarding substantial and compelling circumstances. The Minimum sentences scheme contains unexplained inconsistencies which have resulted in the diverging interpretations of compelling and substantial circumstances by our courts, this inconsistency can be seen in the lack of gradation for increasing levels of offence severity prescribed sentences for rape, some courts have required a higher showing of violence in order to not depart from the prescribed sentences. Some cases have used the prospect of rehabilitation as justification for a departure. This is problematic because the latter factor is present in most cases, as a result, this would lead to unnecessary and unexplainable departures which would then circumvent the legislatures intention in ensuring consistent sentences. This raises questions of whether courts are paying attention to some of the inconsistencies that result from their judgements. This research also looks at prison overcrowding as an unintended consequence of the Act, this is because the Act limits the individualisation of cases thus leading to more offenders receiving lengthy sentences. Courts are expected to consider the relevant factors of each individual case however this is not properly adhered to because the act uses few sentences for different crimes without proper explanation thus affecting prison overcrowding.