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From 12 to 15: girls, boys, gender and sexuality at a high school in the North West Province.
(2023) Rizvi, Rabia Khatoon; Bhana, Deevia
This study examines the construction of gender and sexuality amongst girls and boys between the ages of 12 and 15 at a private school in the North West province of South Africa. It seeks to understand how learners negotiate gender and sexuality at school, and how the school environment and beyond contributes to their construction of gender and sexuality. It also investigates the social processes that promote unequal power relations between boys and girls at school. An ethnographic research method was used to conduct this study and the research instruments were observations, individual interviews and focus group discussions. Participants were selected using a mix of convenience and purposive sampling methods. Many of the participants were boarding learners, which provides a distinct insight into the ways in which the boarding space is a highly generative site for the production of gender and sexuality. A total of 101 learners participated in this study and 69 semi-structured interviews and 16 focus group discussions were conducted with learners across grades 7, 8 and 9. The data were analysed with the theory of social constructionism. The findings show that boys and girls pursue pleasure and desire in a myriad of ways within the school context. They challenge sexual innocence by expressing the types of relationships they would like to enter into and show authority in navigating romantic relationships. They use social media for flirtation and engage in the consumption of pornography. Furthermore, the expansion of sexuality is demonstrated as learners choose to enter into queer relationships. However, this is mitigated by the performance of hegemonic masculinity which places girls in a subordinate position. Girls are slut-shamed for resisting traditional norms of femininity and also experience sexual harassment within the school space. Boys and girls both participate in risky behaviour and there is a culture of silence and complicity that is created around it. Bullying and substance abuse are wielded as opportunities to portray aggressive masculinities and femininities. Girls’ bodies are policed by authority figures and by the boys which restricts their expression of gender and sexuality. This study argues that gender and sexuality are perceived by learners through a binary lens, and that girls largely remain in a subordinate position whilst boys conform to the standards of hegemonic masculinity. It is recommended that platforms need to be created to question these prevailing attitudes and to provide opportunities for boys and girls to explore and alter their traditional beliefs around gender and sexuality.
The geographies of spaces for inclusive education: narratives of teachers in three primary schools in Eswatini.
(2023) Nxumalo, Ceb'sile Phangisile; D’amant, Antoinette
Despite the global shift towards inclusive education, there are still basic tensions, contradictions, and gaps between the design of legislation and the implementation of inclusive, education's objectives in daily school operations. It is uncertain whether Eswatini will continue this tendency of embracing the rhetoric of inclusivity without any real change. Implementing inclusive education policies and transforming schools to make them inclusive is a dynamic and complex process that, not only entails redefining teaching practise, but also necessitates that teachers develop a different sense of themselves as professionals and as individuals, taking into consideration the context in which they work and the power dynamics at play. This study explores the lived experiences of six teachers from three primary schools in urban, semi-urban, and rural Eswatini, as they engage in inclusive education. It also examines how these teachers negotiate and move through the diverse and complex geographies of inclusive education spaces in their schools, while contending with tensions and discrepancies between "real" - action or what is - and the "ideal" - what might be. To understand the daily experiences of teachers in the context of the power-laden spatiality of inclusive education, the use of authentic narratives as a fundamental approach of inquiry focused on listening to and hearing directly from the teachers. By utilizing spatial analysis, we can better understand the forces that shape teachers' perceptions of inclusive education. This research is informed by the idea that teachers are active social constructivists working for the change of classrooms and schools in light of inclusive education and the relationships between space and social practice. Thus, using social constructionism as a theoretical framework, my research enabled me to identify the quality of teachers' experiences with inclusive education, as well as the ways in which power embedded in school geographies mediates the construction of teachers' identities and the narratives that teachers construct to account for their lived experiences. The constructionist framework helps to make sense of the complicated social, historical, and cultural contexts that impact teachers' experiences as they evolve into practitioners who are inclusive. The results of this study show that while teachers face many difficulties, conflicts, contradictions, and complexities; they also have positive and inspirational experiences as they transform to become inclusive practitioners. There is hope for the future of inclusive education because some teachers are starting to re-evaluate how traditional education can address exclusionary practices and take their role as change agents seriously to foster more inclusive and equitable education in classrooms and schools. Others who have not yet personally started to engage with inclusive education at a deep level, are merely presenting a thin veneer of inclusion to satisfy the demands of inclusive education policy expectations. The realization that historically and traditionally dominant unequal relations of power disempower, demoralize, and discourage teachers from challenging existing and institutional structures and practice, embracing transition, and renegotiating their individual and professional identity as teachers for greater inclusive and equitable education; is becoming more and more apparent. This research helped me to understand the diversity within and between individual teachers' classrooms and schools, the multiple realities that have an impact on multiple and intersecting teacher identity construction, and the consequent need to avoid one-dimensional and linear assessments and interpretations of teachers in transition.
Aerial phenotyping tp identify superior sugarcane genotypes.
(2024) Hoffman, Natalie.; Joshi, Sheilesh Vinanay.; Singels, Abrahams.
Sugarcane is a globally important food and bioenergy crop which necessitates continual
improvement through breeding to ensure its sustainable production under increasingly
challenging environments. Compared to other major crops, yield gains in sugarcane have
stagnated worldwide in recent years. This could be attributed to the resource-intensive and
time-consuming nature of breeding a genetically complex crop with long growth cycles and
large, diverse populations. The primary objective of sugarcane breeding is to develop
superior genotypes with enhanced genetic gains, securing sustainable production for the
future. Aerial phenotyping (AP) with high-throughput phenotyping sensor technologies and
unmanned aerial vehicles (UAVs, commonly known as drones) could assist breeding by
increasing selection efficiency and accuracy, uncovering genetic variation for yieldpromoting
traits, and expediting large-scale trial screening. Key physiological traits
governing canopy development and water use, namely green canopy cover (GCC) and
stomatal conductance (gs), can be estimated from the aerially measured Normalized
Difference Vegetation Index (NDVI) and canopy temperature (Tc), respectively. While
promising, further research is required to evaluate the efficacy of AP in breeding.
The study aimed to develop and test an AP procedure for identifying superior genotypes in
sugarcane breeding. The specific objectives were to: (1) determine the impacts of ground
(GCC and gs) and aerially measured traits (NDVI and Tc), on stalk dry mass yield (SDM)
under well-watered (WW) and water deficit (WD) conditions; (2) develop an AP procedure
for estimating gs, GCC and SDM from Tc and NDVI; (3) determine the genetic variation
and broad-sense heritability of ground and aerially measured traits; (4) evaluate the
feasibility and potential benefit of implementing AP to identify superior genotypes in
breeding. These aims and objectives were addressed in three experimental phases.
An unreplicated pilot trial with two genotypes grown under WW and WD conditions (~ 200
m2 in total) was used to establish preliminary relationships between ground and aerially
measured traits under varying canopy and moisture conditions. Key findings were that
FIPAR (fractional interception of photosynthetically active radiation - a surrogate measure
of GCC) measured on the ground could be reliably estimated from NDVI, though the
relationship required further investigation at partial canopy cover. Tc could be used to
distinguish differences in measured gs between water treatments under moderate to severe
stress conditions only. Overall, the experiment was used to formulate a preliminary AP
protocol, with recommendations for further improvement in the subsequent phase.
A replicated field trial with 54 genotypes, grown under WW and WD conditions (~ 3 ha in
total) in plant and first ratoon crops, was used to assess trait correlations, genetic variation
and broad-sense heritability of traits, and to refine the AP procedure. In line with previous
research, the study confirmed FIPAR and gs as influential traits for determining SDM.
FIPAR, measured at 2-3 months after crop start, could be used to identify high- and lowyielding
genotypes, and could be predicted well from NDVI, at partial canopy for wellwatered
crops. Breeding programs for irrigated environments could benefit from the early
identification of superior genotypes if traits with high heritability, like FIPAR, can be
accurately and rapidly phenotyped. Furthermore, results suggested that high gs benefits wellwatered
crops, while relatively low gs could be advantageous in dry environments, though
this requires further validation. Phenotyping of gs from Tc was mostly unreliable, and its
practical application in breeding programs requires further evaluation on a larger, genetically
diverse population with improved measurement procedures. It was concluded that NDVI and
Tc, which both showed significant genotypic variation and moderate to high heritability,
could be used to identify high- and low-yielding genotypes when measured early in the crop
cycle in young, partially canopied, well-watered crops planted in multi-row plots. Novel
results also showed potential for screening of drought tolerance using water treatment
differences in Tc and SDM, which has not been reported previously for sugarcane. Overall,
this research was used to establish an AP procedure for subsequent use in breeding trials.
Lastly, the AP procedure was implemented in two rainfed early-stage breeding trials, with
1770 to 2130 genotypes, planted in replicated single-row plots over ~3.5 – 6 ha. This
validation phase was used to test the utility of AP for enhancing selection accuracy and
efficiency and contribute to yield improvement. The limited number of flights in the first
trial prevented adequate capture of temporal and genotypic variations in aerially measured
traits, which are necessary for accurate yield prediction. In the second trial, early estimates
of NDVI and Tc, measured approximately 1.5 to 3 months after crop start in partially
canopied, well-watered crops, showed significant genotypic variation, moderate to high
heritability, and significant correlation with yield. Tc was also significantly correlated with
yield when measured shortly after canopy closure but before row overlap due to crop growth.
Despite these promising results, the AP procedure implemented in these early-stage breeding
trials did not achieve the precision required for genotype selection. A comparison of direct
(SDM-based) and indirect (based on aerially measured traits) selection approaches showed
that the number of positive matches was mostly offset by a larger number of incorrectly
identified genotypes using aerially measured traits. It was concluded that the effectiveness
of AP in breeding is currently hindered by limitations in the precision of aerial measurements
and challenges in breeding trial execution.
The findings from this study highlight the potential and limitations of AP for physiological
breeding. AP holds great promise for identifying genetic variation in yield-promoting traits,
which could be leveraged in breeding for the identification of superior genotypes in irrigated
environments, however further research is required to fully realize this potential. It is
recommended to modify the design of early-stage trials by increasing plot length, number of
rows, and row-spacing to facilitate accurate estimation of aerially measured traits using the
developed AP procedure. Further efforts are also needed to overcome challenges inherent in
breeding trial execution, such as lengthy planting periods introducing biases in early vigour,
and variability in field soil composition, which directly and indirectly affect the quality of
ground and aerially measured data. Should these recommendations be implemented, early
screening of trials using AP could lead to shorter breeding cycles, the discovery of novel
genetic variations, and improved selection efficiency, ultimately reducing the resourceintensive
nature of traditional methods through early elimination of inferior genotypes from
the program.
In conclusion, this study demonstrates the potential of AP to enhance sugarcane breeding by
facilitating the early detection of important yield-promoting traits, particularly in wellwatered
crops. While AP shows promise to enhance sugarcane breeding, further work in
refining its application is essential to fully realize its benefits. These research findings
provide a strong foundation for future efforts to develop innovative breeding strategies and
precision agriculture technologies.
Identification of cowpea (vigna unguiculata (L) (walp) genotypes and genetic improvement for enhanced yield and nutritional quality.
(2023) Gumede, Mbali Thembi.; Mabhaudhi, Tafadzwanashe.; Gerrano, Abe Shegro.
Cowpea (Vigna unguiculata (L.) Walp) is a staple legume crop with potential to address food
insecurity and malnutrition in the Sub-Saharan Africa (SSA). It is also among the neglected
underutilized legume crop species in the region. The crop’s yield production has never met the
potential yields of the crop in the SSA. In addition, given its nutritional value, ability to
withstand extreme environmental conditions, nitrogen fixation ability and its greater potential
to address nutrient deficiencies and food insecurity in the SSA. These attributes make cowpea
an ideal crop to sustainable future for the people and environment. There is a need to develop
cowpea varieties that are high yielding with high nutritional values to combat food insecurity.
Therefore, the objectives of the study were: (1) to assess the genotype by environment
interaction effect and select cowpea genotypes with high grain yield and adaptation across
selected cowpea growing environments in South Africa, (2) to assess the phenotypic variability
and correlation analysis in cowpea based on yield and yield related traits, (3) to evaluate the
variations of nutritional content and phytochemical compositions among cowpea genotypes
under diverse environments, (4) to assess the genetic diversity among cowpea genotypes using
single nucleotide polymorphism (SNP) markers, and to select distinct and complementary
genotypes for developing improved cultivars and (5) to determine the combining ability effects
and gene action controlling the yield and yield-related traits among selected cowpea parental
genotypes and their progenies.
The first study assessed the extent of genotype by environment interaction (GEI) of cowpea
genotype to the influence of genotype (G), environment (E) and their interaction (GEI) effects
on grain yield in cowpea and to assess the stability of cowpea genotypes to identify stable and
high-yielding genotypes for broad or narrow adaptation to improve cowpea productivity in
South Africa and identify the identical agro-ecologies using analysis of variance (ANOVA),
additive main effects and multiplicative interaction (AMMI) and the genotype-by-environment
interaction (GGE) biplot analyses. The AMMI ANOVA showed the significant GEI effect
which accounted for 57% variation, whereas genotype and environment main effects accounted
for 29% and 13% variation, respectively. The AMMI stability values (ASV) analysis identified
genotype Acc-Cowp44 as the most stable genotype recording the lowest ASV of 0.03.
The biplot depicted eight sectors and environments were clustered into three of the eight sector
whereby E4 (Brits 2020/2021), E5 (Loskop 2020/2021), E6 (Mafikeng 2020/2021) and E7
(Polokwane 2020/2021) which formed a mega-environment and the second sector which
involved environments E1 (Brits 2019/2020), E2 (Loskop 2019/2020) and E3 (Roodeplaat
2019/2020) formed one mega-environment. The cowpea genotypes Acc-Cowp38, Acc-Cowp2,
Acc-Cowp9, Acc-Cowp5 and Acc-Cowp39 were identified as ideal for grain yield, in that
order. These genotypes are recommended for production in South Africa or in similar agroecologies,
and for incorporation in future breeding programs targeting genetic improvement
for grain yield.
The second study assessed 50 cowpea genotypes using yield and yield components to
determine the phenotypic correlations among them and selection of best performing genotypes
among tested genotypes for enhanced cultivar development. The study revealed the significant
differences at 5% and 1% level of probability among the assessed grain yield and yield
component traits. The study further indicates that number of pods per plant (NPP), pod length
(PL), number of seeds per pod (NSP) and hundred seed weight (HSW) had significant and
positive correlations with grain yield, therefore these traits can be used as a proxy trait for
increased grain yield. Similarly, the principal component analysis (PCA) biplot identified
number of branches (NB), number of pods per plant (NPP), pod length (PL), pod width (PW),
number of seeds per pod (NSP), and hundred seed weight (HSW) as the important traits in the
production of grain yield. Genotypes Acc-Cowp2, 98K_5301, Acc-Cowp4, Acc-Cowp17 and
Acc-Cowp9 were grouped together based on their high exhibition of NPP, PW, NSP, PL, HSW
and grain yield (GY). The selected genotypes could be considered as potential sources of gene
to improve these traits and could serve as parental genotypes in breeding programs targeting
enhanced high-yielding varieties.
The third study assessed the nutritional and phytochemical traits among the 50 cowpea
genotypes to select superior lines with high nutritional compositions for cultivar development
for nutritional quality. The study highlighted the significant effects for all nutritional and
phytochemical traits for genotype, environment, and genotype by environment interaction
evaluated except for flavonoids and fat content. Genotypes Acc-Cowp6, Acc-Cowp17, Acc-
Cowp14, 98K_5301, Acc-Cowp9, Acc-Cowp32, Acc-Cowp9, Acc-Cowp4, Acc-Cowp16 and
Acc-Cowp21 were selected based on high concentration of Ca, Mg, P, Na and Zn. Genotype
Acc-Cowp31 and Acc-Cowp13 were highly associated with protein content while genotype
Acc-Cowp39 were in close association with fat content. Further, genotypes Acc-Cowp34, Acc-
Cowp18, Acc-Cowp48, Acc-Cowp22, Acc-Cowp26, Acc-Cowp49 and Acc-Cowp28 had low
concentrations of total phenolic, flavonoids and condensed tannins.
The fourth study used 90 genetically diverse cowpea to assess the magnitude of the genetic
diversity and population structure among cowpea genotypes using single nucleotide
polymorphisms (SNP) markers. The study revealed that 49% of the selected SNP markers were
highly polymorphic and efficiently discriminate the tested cowpea accessions. The low
heterozygosity and the high inbreeding coefficients observed among cowpea varieties indicate
that the accessions reached an acceptable level of homozygosity. The model-based (structure
analysis) and distance-based (UPGM) clustering approaches were used in this study. The
model-based analysis revealed the presence of four subpopulations at K = 4 whereas the
distance-based cluster analysis classified the cowpea accessions into three distinct clusters. The
subpopulations identified exhibited a high level of genetic diversity and were moderately
differentiated. This result suggests that the accessions studied are unique and have greater
potential to contribute to new varieties for breeding programs in South Africa.
The fifth study determined the combining ability effects and gene action controlling the yield
and its related traits among 10 selected parental genotypes and 45 crosses using the half diallel
mating design. There were significant genotypic, environmental and their interaction effects
for almost all traits except leaf length (LL) and number of seeds per pod (NSP) exhibited by
both parental genotypes and their progenies. The GCA effects were significant for LW, PL,
NSP and HSW whereas the SCA effects were significant for pod width (PW) only. The GCA
x environmental interaction effects were highly significant for all traits while the SCA x
environmental interaction effects were significant for all the traits except plant height (PH) and
LL. The parents Acc-cowp17, Acc-cowp31, Acc-cowp9, Acc-cowp5, Acc-cowp38 and Acccowp19
were identified as good combiners for grain yield and its associated traits productivity.
The newly developed progenies Acc-Cowp31 x Acc-Cowp5, Acc-Cowp38 x Acc-Cowp19,
Acc-Cowp9 x Acc-Cowp2, Acc-Cowp47 x Acc-Cowp9, Acc-Cowp31 x Acc-Cowp9, Acc-
Cowp32 x Acc-Cowp9, Acc-Cowp47 x Acc-Cowp38, and Acc-Cowp17 x Acc-Cowp38 were
found to be the best performing due to their desirable SCA effects for enhanced grain yield.
The study revealed that trait expression was controlled by both additive and non-additive effect
with the additive gene action shown to be the important in controlling traits including NB, LW,
NPP, NSP and HSW.
Diffuse radio emission in ACTPol clusters.
(2021) Sikhosana, Sinenhlanhla Precious.; Moodley, Kavilan.; Knowles, Kenda Leigh.; Hilton, Matthew James.
Low-frequency radio observations of galaxy clusters reveal cluster-scale diffuse emission that
is not associated with individual galaxies. Studying the properties of these diffuse radio sources
gives insight into astrophysical processes such as cosmic ray transportation in the intracluster
medium (ICM). Observations have linked the formation of radio halos and relics with turbulence
caused by cluster mergers and the formation of mini-halos to gas sloshing in cool-core clusters.
Statistical studies of large galaxy cluster samples have been used to determine how the radio
properties of diffuse emission scale with the mass and X-ray luminosity of the host clusters.
Such studies are crucial for refining the formation theories of diffuse emission. New generation
telescopes with wide bandwidths and high sensitivity such as the upgraded Giant Metrewave Radio
Telescope (uGMRT) andMeerKAT are advantageous for the study of faint extended emission
in large cluster samples.
The main aim of this thesis was to do an in-depth study of the diffuse radio emission using
a cluster sample that spans a wider mass and redshift range compared to the currently studied
parameter space. We developed data reduction techniques for calibrating data from telescopes
such as uGMRT and MeerKAT. The wide bandwidth of these telescopes introduces directional
dependent effects (DDEs) that make the calibration process extremely complicated. However,
such observations are excellent for studies of the faint diffuse emission and in-band spectral
indices of this emission.
In the first part of this thesis, we focused on the study of diffuse radio emission in a Sunyaev-
Zeldovich (SZ) selected sample of clusters. These clusters were observed by the Atacama Cosmology
Telescope’s Polarimetric extension (ACTPol). We used archival and new GMRT observations
for the radio analysis of this sample. We reported newly detected diffuse emission in the
following clusters: a radio halo and revived fossil plasma in ACT-CL J0137.4 0827, a radio relic
in ACT-CL J2128.4+0135, and a candidate relic in ACT-CL J0022.2 0036. The radio analysis
of the full sample revealed that the fraction of clusters in the sample hosting diffuse emission
is 26.7% excluding candidate emission and 30% when it is included. The detection rate of the
diffuse emission over all categories is lower than the detection rates reported in literature. We
note that this may be because the sample comprised high redshift (z ¡ 0.5) and low mass clusters
(M500c;SZ 5 1014 Md), though future more sensitive observations of these clusters could reveal
fainter diffuse emission structures. We compared our results to the most recent radio halo and radio
relic scaling relations. The radio halo P1:4GHz M500 scaling relation plot indicates that a few
flatter spectrum radio halos are located in the region previously known to be populated by ultrasteep
spectrum radio halos (USSRHs). Finally, we presented preliminary results of the uGMRT
wideband backend (GWB) data reduction for ACT-CL J0034.4+0225, ACT-CL J0137.4 0827,
and ACT-CL J2128.4+0135. We prioritised these clusters because the narrowband data revealed
that they host diffuse emission. However, once the data reduction algorithm is improved, we
will reduce the remaining clusters with non-detections. Comparing the GWB results to the narrowband
GMRT data, we note that the radio halo observed in ACT-CL J0137.4 0827 is more
extended in the GWB data. The diffuse emission is detected at a higher signal-to-noise ratio in
the GWB images for the three clusters. We note that an improvement in the GWB reduction
algorithm might reveal diffuse emission that was not detected in the narrowband data.
In the second part of the thesis, we used MeerKAT observations to study diffuse emission in
the Bullet Cluster (1E0657 56), RXCJ1314.4 2515, Abell 3562, and Abell 3558. We detected
new extended features in the radio halos hosted by the Bullet cluster and Abell 3562. We assume
that the decrement feature in the Bullet cluster might be an indication of a second wave of merger
activity. The ridge feature in the peripheral region of the radio halo in Abell 3562 overlaps with
the edge of the X-ray emission. Hence, we assume that the feature might be related to a shock
region. We also reported the detection of a new mini-halo in Abell 3558. MeerKAT’s sensitivity
and wide bandwidth enabled us to perform in-band spectral index studies and produce spectral
index maps for the Bullet cluster, RXCJ1314.4 2515, and Abell 3562. The spectral index maps
of the relics in the Bullet cluster and RXCJ1314.4 2515 indicate a spectral steepening towards
the cluster center, while the spectral index map of the radio halo in the Bullet cluster indicates
radial spectral steepening. The spectral index map of Abell 3562 indicates that the radio halo
and ridge have similar spectral index variations, which suggests that the ridge feature is related
to the radio halo.