Research Articles (Plant and Soil Sciences)

Permanent URI for this collectionhttp://hdl.handle.net/2263/99072

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Self-regulated learning strategies for success in an online first-year chemistry course
(Royal Society of Chemistry, 2025-01) Rakhunwana, Langanani; Kritzinger, Angelique; Pilcher, Lynne A.; lynne.pilcher@up.ac.za
During their first year of study at university, many students encounter challenges in developing learning strategies that align with success in the courses in which they are enrolled. The emergence of the COVID-19 pandemic heightened the challenges as universities were compelled to transition to online learning. Therefore, this study investigated the self-reported use of learning strategies in a first-year chemistry course delivered online due to the COVID-19 pandemic to identify learning strategies associated with success. Grounded in self-regulated learning (SRL) theory, a case study approach with an explanatory mixed methods design was adopted. Quantitative data were collected using a hybrid of the Motivated Strategies for Learning Questionnaire and the Online Self-regulated Learning Questionnaire. Follow-up open-ended questions were emailed to the students for the qualitative part of the study. Statistical analysis of the quantitative data was performed using SPSS and RUMM2030, while thematic analysis was applied to the qualitative data. Students reported more frequent use of SRL strategies of environment structuring, effort regulation, and elaboration. Conversely, critical thinking, task strategies, help-seeking, and peer learning were reportedly used less often. SRL strategies linked with success in the course were identified as effort regulation, goal setting, and time management. The findings from the qualitative data revealed an impact of online learning due to the pandemic on the use of peer learning and help-seeking strategies. The paper discusses the implications of these findings for educational practices, particularly in the context of hybrid learning in the post-pandemic era.
Repeat photography reveals long-term climate change impacts on sub-Antarctic tundra vegetation
(Wiley, 2024-11) Van der Merwe, Stephni; Greve, Michelle; Hoffman, Michael Timm; Skowno, Andrew Luke; Pallett, Nita; Terauds, Aleks; Chown, Steven L.; Cramer, Michael D.
QUESTIONS: At high latitudes, anthropogenic climate change and invasive species threaten biodiversity, often with interacting effects. Climate change not only impacts native plant species directly by driving distribution and abundance of species, but indirectly through the influence on community dynamics and habitat suitability to invasive species. A key obstacle to quantifying vegetation change in the sub-Antarctic is the scarcity of cloud-free satellite imagery in a region with near-permanent cloud cover and lack of long-term plot data. In this paper, we aim to address the following QUESTIONS: how has vegetation in the sub-Antarctic changed between 1965 and 2020? What are the roles of climate change and invasive species in driving these changes? LOCATION: The study was conducted on Marion Island in the sub-Antarctica. METHODS: We quantified vegetation change by analysing repeat ground photography between 1965 and 2020, accompanied by an analysis of climate trends and invasive plant species’ cover changes over the same period. RESULTS: Total vegetation cover was significantly higher in 2020 than in 1965 in all habitats other than in the coastal saltspray habitat, indicating an increase in overall biomass on the island. The more responsive ‘generalist’ plant species have expanded across the island, whilst the more ‘specialised’ plant species have not significantly changed in cover, with the exception of the mire graminoids, which have declined. Marion Island has thus undergone significant vegetation change, showing a greening trend across most habitats in the last five decades. This has been accompanied by aridification, an increase in mean air temperature, changes in wind direction and wind speed, and an increase in invasive mouse populations. The three most widespread invasive plant species have also expanded their ranges, especially in areas influenced by animal disturbance and nutrient input. CONCLUSIONS: In congruence with research from Northern-hemisphere tundra and other islands in the sub-Antarctic, these results provide substantive empirical evidence for the interacting effects of climate change and invasive species on subAntarctic tundra vegetation, as has long been predicted.
Effectiveness of Rhizobium tropici sp. strain UD5 peat biofertilizer inoculant on growth, yield, and nitrogen concentration of common bean
(MDPI, 2024-03) Gatabazi, Auges; Ndhlala, Ashwell Rungano; Mvondo-She, Mireille Asanzi; Mpai, Semakaleng
Common bean (Phaseolus vulgaris L.) ranks among the most produced and consumed legume crops and contains essential macro- and micronutrients. Grain yield of the food crop is markedly decreased by poor management, especially a lack of additional essential nutrient elements through the application of fertilizers. In addition to the application of fertilizers, scholarly research and crop farmers have shown that the use of biofertilizer inoculants improves the yield of legume crops. The objective of this research study was to assess the effectiveness of peat-based Rhizobium tropici sp. UD5 on the growth, yield, and nitrogen concentration of common bean. The peat inoculant contained 6.5 × 109 viable cells/g. The experiment was conducted in two climatic zones, as described by the Koppen–Gieger climatic classification system. Treatments involved the peat-based inoculant Rhizobium tropici (T0 = 0 g without inoculation, T1 = 250 g of peat inoculant of strain UD5 for 50 kg seeds, T2 = 500 g of inoculant of strain UD5, and T3 = 200 g of comparative peat inoculant). The results indicated that common-bean-inoculated formulation of R. tropici sp. strain UD5 increased the following parameters compared to the controls: plant height (T1 = 18.22%, T2 = 20.41%, and T3 = 19.93% for bioclimatic zone 1; T1 = 16.78%, T2 = 20.71%, and T3 = 19.93% for bioclimatic zone 2), root length (T1 = 13.26%, T2 = 21.28%, and T3 = 19.38% for zone 1; T1 = 15.06%, T2 = 23.70%, and T3 = 19.20% for zone 2), number of nodules (T1 = 1162.57%, T2 = 1166.36%, and T3 = 1180.30% for zone 1; T1 = 1575%, T2 = 1616.5%, and T3 = 1608.25% for zone 2), size of nodules (T1 = 224.07%, T2 = 224.07%, and T3 = 208.33% for zone 1; T1 = 166.4%, T2 = 180%, and T3 = 140% for zone 2), and yield (T1 = 40.49%, T2 = 47.10%, and T3 = 45.45% for zone 1; T1 = 62.16%, T2 = 54.05%, and T3 = 58.55% for zone 2). R. tropici sp. UD5 peat inoculant formulation also increased the nitrogen concentration in leaves compared to the control (T1 = 3.75%, T2 = 1.12%, and T3 = 8.72%) in both bioclimatic zones. The findings of this study provide significant information on the positive effect of R. tropic UD5 strain peat inoculant application in the improvement of plant growth, development, and yield through the formation of nodules.
Manipulating button mushroom casing affects the disease dynamics of blotch and green mold disease
(Elsevier, 2024-12) O’Connor, Eoin; Vieira, Fabricio R.; Di Tomassi, Isako; Richardson, Rachel; Hockett, Kevin L.; Bull, Carolee T.; Pecchia, John A.
Productive cultivation of the button mushroom (Agaricus bisporus) relies on the use of selective substrates and effective disease management. In extending our previous work on manipulating the developmental microbiome (devome), this study employs the strategy of substrate passaging to explore its effects on crop outcomes and disease dynamics. Here we subjected the casing substrate to ten cycles of passaging. This manipulated substrate stimulated early pinning (primordia formation) by at least three days. Passaged casing also altered disease dy namics when challenged with two commercially important A. bisporus pathogens, Pseudomonas tolaasii (causing bacterial blotch) and Trichoderma aggressivum f. aggressivum (responsible for green mold). Passaged casing had a suppressive effect on blotch disease and a conducive effect on green mold disease. Blotch suppression resulted in a significantly higher yield of asymptomatic mushrooms in all three mushroom harvests (flushes) and in the overall crop yield. Blotch severity was also significantly reduced in passaged casing compared to standard casing due to a lower yield of mushrooms with the highest degree of blotch disease expression. Green mold disease expression was markedly higher in passaged casing, leading to lower numbers of asymptomatic mushrooms. Zones where no growth of hyphae or mushrooms were also observed in passaged casing due to green mold disease pressure. The stimulating effect of passaged casing on mushroom development and the dynamic out comes for disease challenge from two distinct, commercially damaging diseases, demonstrates the potential for passaged casing to be used as material to study more sustainable mushroom production and disease management practices.
Unlocking wheat drought tolerance : the synergy of omics data and computational intelligence
(Wiley, 2024-11) Le Roux, Marlon-Schylor L.; Kunert, Karl J.; Cullis, Christopher A.; Botha, Anna-Maria
Currently, approximately 4.5 billion people in developing countries consider bread wheat (Triticum aestivum L.) as a staple food crop, as it is a key source of daily calories. Wheat is, therefore, ranked the second most important grain crop in the developing world. Climate change associated with severe drought conditions and rising global mean temperatures has resulted in sporadic soil water shortage causing severe yield loss in wheat. While drought responses in wheat crosscut all omics levels, our understanding of water-deficit response mechanisms, particularly in the context of wheat, remains incomplete. This understanding can be significantly advanced with the aid of computational intelligence, more often referred to as artificial intelligence (AI) models, especially those leveraging machine learning and deep learning tools. However, there is an imminent and continuous need for omics and AI integration. Yet, a foundational step to this integration is the clear contextualization of drought—a task that has long posed challenges for the scientific community, including plant breeders. Nonetheless, literature indicates significant progress in all omics fields, with large amounts of potentially informative omics data being produced daily. Despite this, it remains questionable whether the reported big datasets have met food security expectations, as translating omics data into pre-breeding initiatives remains a challenge, which is likely due to data accessibility or reproducibility issues, as interpreting omics data poses big challenges to plant breeders. This review, therefore, focuses on these omics perspectives and explores how AI might act as an interface to make this data more insightful. We examine this in the context of drought stress, with a focus on wheat.
A comprehensive review of recent advances in membrane innovations for efficient heavy metal removal from mine effluents
(Elsevier, 2025-03) Zulu, Eunice; Ramasamy, Subbaiya; Khoabane Sikhwivhilu, Keneiloe; Syampungani, Stephen
The growing global challenge of water scarcity, intensified by industrialization and population growth has heightened the need for effective wastewater management in industries, including the mining sector. Mining operations discharge substantial volumes of wastewater laden with toxic metal such as copper, iron, cobalt, lead and mercury which poses significant environmental as well as human health risk. Efficient wastewater treatment is crucial to mitigate these effects. While technological advancements have improved mine effluents treatment, there remains a need for advanced methods that enable not only removal of the toxic metals but also recovery of resources such as valuable metals and water. Due to its high efficiency, selectivity and low environmental footprint, membrane technology has gained attention especially in the treatment of various mine effluent. Though fouling is a major challenge in its implementation. The review gives an updated overview on the membrane technology in mining effluent treatment, examining the performance of various membranes (pressure driven membrane, thermal and concentration) in removal of metals and recycle of valuable resources from mine effluents such Acid Mine Drainage (AMD) and other mine effluents. It also examines innovative approaches such as pre-treatment processes, hybrid membrane system as well as the use nanocomposites polymeric membrane. Furthermore, the recent advances in membrane modification techniques such as chemical vapour deposition, sol-gel process, lithography, Atomic layer deposition, layer by layer and electrospinning have been discussed. Studies show that >95 % separation efficiency,> 85 % water recovery and >90 % metal recovery for hybrid membrane processes and chemical precipitation. The recovered metals show high purity of >99 %. Studies indicate that standalone membrane system have limitations in recovery of metals but hybrid systems (membrane coupled with other complementary methods) can achieve better results. This review identifies future direction for advancing membrane technology in sustainable mine wastewater management for improved environmental as well as mine operations.
The nitrogen fertilizer value of selected South African biosolids as affected by drying depth on beds
(International Centre for Sustainable Development of Energy, Water and Environment Systems, 2021-06) Tesfamariam, Eyob Habte; Malobane, Elvis M.; Cogger, Craig G.; Mbakwe, Ikenna
Wastewater treatment and post-treatment drying techniques play a crucial role on the fertilizer value of biosolids. The aim of this study was to investigate: the nitrogen fertilizer value of biosolids from selected biosolid treatment and post treatment dewatering techniques (a) and the effect of drying depth and time on the nitrogen content of biosolid (b). To achieve the first aim, laboratory nitrogen mineralization study was conducted using thermally-hydrolysed-biosolid, activated-biosolid, and anaerobically-digested-biosolids. To achieve the second aim five drying depths were tested (5, 10, 15, 20 and 25 cm). Nitrogen release per tonne biosolid applied was highest for activated (24 kg), and lowest for anaerobically-digested-biosolid (6 kg). Highest total nitrogen was reported for 10 cm drying depth (3.63%) (4 weeks) and lowest for 25 cm (2.64%) (8 weeks). Selection of appropriate biosolid treatment and dewatering technique is key to improve fertilizer value of biosolids.

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