Research Articles (Plant Production and Soil Science)

Permanent URI for this collectionhttp://hdl.handle.net/2263/1729

A collection containing some of the full text peer-reviewed/ refereed articles published by researchers from the
Department of Plant Production and Soil Science

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Proposals to conserve the name Aloe mitriformis with a conserved type and the name A. microstigma against A. perfoliata (Asphodelaceae: Alooideae)
(Wiley, 2025-06) Klopper, Ronell Renett; Smith, Gideon F.; Van Wyk, Abraham Erasmus (Braam)
No abstract available.
In vitro antiplasmodial activity and cytotoxicity of three Ziziphus (Rhamnaceae) species from South Africa
(Elsevier, 2025-06) Mabuza, Mcebisi Junior; Kaiser, M.; Tshikalange, T.E.; Yusuf, Abdullahi Ahmed; Bapela, Mahwahwatse Johanna
Please read abstract in the article.
Occurrence and genotypic characterization of selected multidrug-resistant ESKAPE-E pathogens isolated from integrated smallholder fresh produce farms
(Elsevier, 2025-06) Viviers, Sheldon A.; Richter-Mouton, Loandi; Featherston, Jonathan; Korsten, Lise; lise.korsten@up.ac.za
Antimicrobial resistance (AMR) ranks among the top ten global public health threats, with extended-spectrum β-lactamase (ESBL)-producing Enterobacterales and Pseudomonas aeruginosa emerging as multidrug-resistant (MDR) priority pathogens. This study aimed to evaluate the presence and characteristics (phenotypic and genotypic AMR profiles) of ESBL/AmpC-producing Enterobacterales and P. aeruginosa isolates obtained from the water-soil-plant nexus on smallholder fresh produce farms in South Africa. Samples of irrigation water (n = 44), soil (n = 85), and fresh produce (n = 95) were collected from six smallholder farms. Potential MDR bacteria were isolated using selective enrichment, chromogenic media, and identified with MALDI-TOF MS. Antimicrobial resistance was assessed via double-disk diffusion against 13 different antibiotic classes, while 20 selected isolates were genotypically characterized using whole-genome sequencing (WGS) (Illumina MiSeq). ESBL/AmpC-producing isolates were detected in 17% of samples (38/224), primarily from fresh produce (54%), followed by soil (31%) and water (15%). The dominant Enterobacterales species identified from all three matrices included Enterobacter spp. (26%), Klebsiella spp. (26%), Serratia spp. (17%), and Escherichia coli (9%). Phenotypically, 47% and 43% of the isolates were classified as ESBL and AmpC-producers, respectively, with resistance to beta-lactams, aminoglycosides, and glycylcyclines. Notably, WGS analysis indicated the presence of clinically significant AMR and virulence genes among isolates from the environment, particularly those associated with mobile genetic elements. The results from the study add to the limited national and international knowledge of AMR prevalence in the smallholder agricultural landscape, needed for the introduction of appropriate intervention strategies and future risk assessment of the informal supply chain.
Entomopathogenic nematodes : commercial use and future perspectives
(Elsevier, 2025-09) Ramakuwela, Tshimangadzo; Tarasco, Eustachio; Chavarría-Hernández, Norberto; Toepfer, Stefan; tshimangadzo.ramakuwela@up.ac.za
The 100 years of research, development, commercialization and use of entomopathogenic nematodes (EPN) since their discovery in the 1920s have seen impressive progress. Nowadays, many EPN products, based on a relatively limited number of EPN species, are commercially available in most world regions. This paper presents a review of EPN commercialization and examples of EPN use in field crops such as maize and in agroforestry ecosystems. It demonstrates how EPN have become an important tool in biological control of insect pests offering many advantages over chemicals. These include farmer and consumer safety, minimal damage to natural enemies, no problems with pollinators, and no environmental pollution. All of these attributes are essential for an advanced and sustainable integrated pest management strategy. We explored future potential of commercialization and adoption of EPN-based biocontrol products. The future may lie in several advances: i) The ability to tailor the use of EPN to broad as well as to local agricultural needs. ii) Enhancing their shelf life and efficacy through genetic improvements. iii) Refining application technologies. iv) Improving mass production (including machine learning using production data). v Reducing production and delivery costs, considering EPN as safe agents and therefore reducing registration burdens. Vi) Finally, expanding their use to a larger market such as to new pest species and crops. With continued research and innovation, EPN could become a cornerstone of sustainable pest management strategies in an increasing number of countries.
Improving the antinutritional profiles of common beans (Phaseolus vulgaris L.) moderately impacts carotenoid bioaccessibility but not mineral solubility
(Nature Research, 2024-05-24) Alvarado‑Ramos , Katherine; Bravo‑Nunez , Angela; Halimi , Charlotte; Maillot , Matthieu; Icard‑Verniere, Christele; Forti, Chiara; Preite, Chiara; Ferrari, Luisa; Sala, Tea; Losa, Alessia; Cominelli, Eleonora; Sparvoli, Emanuela Camilli Francesca; Lisciani, Stefania Marconi Silvia; Georgé, Stephane; Mouquet-Rivier, Claire; Kunert, Karl J.
Common beans are a common staple food with valuable nutritional qualities, but their high contents in antinutritional factors (ANFs) can decrease the bioavailability of (i) fat-soluble micronutrients including carotenoids and (ii) minerals. Our objective was to select ANF-poor bean lines that would not interfere with carotenoid and mineral bioavailability. To achieve this objective, seeds of commercial and experimental Phaseolus vulgaris L. bean lines were produced for 2 years and the bean’s content in ANFs (saponins, phytates, tannins, total polyphenols) was assessed. We then measured carotenoid bioaccessibility and mineral solubility (i.e. the fraction of carotenoid and mineral that transfer into the aqueous phase of the digesta and is therefore absorbable) from prepared beans using in vitro digestion. All beans contained at least 200 mg/100 g of saponins and 2.44 mg/100 g tannins. The low phytic acid (lpa) lines, lpa1 and lpa12 exhibited lower phytate levels (≈ − 80%, p = 0.007 and p = 0.02) than their control BAT-93. However, this decrease had no significant impact on mineral solubility. HP5/1 (lpa + phaseolin and lectin PHA-E free) bean line, induced an improvement in carotenoid bioaccessibility (i.e., + 38%, p = 0.02, and + 32%, p = 0.005, for phytofluene bioaccessibility in 2021 and 2022, respectively). We conclude that decrease in the phytate bean content should thus likely be associated to decreases in other ANFs such as tannins or polyphenols to lead to significant improvement of micronutrient bioaccessibility.
Standing vegetation and seed bank patterns paint a bleak picture for urban grassland restoration
(Springer, 2025-04) Malherbe, Misha; Le Roux, Peter Christiaan; Haussmann, Natalie S.; peter.leroux@up.ac.za
Urbanisation and urban sprawl are major drivers of global habitat transformation and biodiversity loss. Natural vegetation in urban areas is confined to remnant patches and, as a result, the conservation of these patches of vegetation is becoming increasingly important for biodiversity conservation. Globally grasslands experience high rates of transformation and are threatened by expanding urban areas, causing fragmentation, and facilitating the spread of invasive species. This study explores how above- and belowground vegetation communities within remnant grassland patches vary as a function of patch connectivity and patch size in the City of Tshwane, Gauteng, South Africa. We sampled twelve sites from eleven nature reserves within Tshwane to investigate the relationships between urbanisation and vegetation characteristics. Tshwane’s grassland patches have high levels of invasion, with alien species making up a considerable portion of both standing (13% richness and a third of cover) and seed bank vegetation (31% richness and 26% abundance). Furthermore, we found low similarity between standing vegetation and the seed bank (mean ± SD = 0.25 ± 0.06). Neither road density nor reserve size were related to the total cover or richness of vascular plants, nor the cover or richness of alien species. Similarly, neither variable predicted above-belowground similarity. This suggests that the connectivity of remnant grassland patches does not have any significant effect on vegetation characteristics in this disturbed urban environment. Our results indicate that restoration relying only on natural revegetation from the seed bank is unlikely to be effective and we suggest that active restoration interventions, such as reseeding and invasive species control, may be needed to restore these grasslands and improve their long-term conservation value.
Avocado rhizosphere community profiling : white root rot and its impact on microbial composition
(Frontiers Media, 2025-05) Magagula, Phinda; Swart, Velushka; Fourie, Arista; Vermeulen, Alicia; Nelson, Johannes Harold; Van Rooyen, Zelda; Van den Berg, Noelani; noelani.vdberg@fabi.up.ac.za
INTRODUCTION : The avocado rhizosphere supports diverse microbial communities essential for plant health and defence against pathogens. This study aimed to investigate the impact of Dematophora necatrix, the causal agent of white root rot (WRR), on the microbial composition and soil physicochemical properties of infected and non-infected avocado trees in two South African orchards. METHODS : ITS and 16S metabarcoding was used to compare the composition and diversity of the rhizosphere microbiome. Soil physicochemical properties were also assessed, and culturable bacterial and fungal isolates from the rhizosphere were screened for antagonistic activity against D. necatrix. RESULTS : We found that D. necatrix did not significantly alter overall microbial diversity but influenced relative abundance of specific taxa. In Orchard A, dominant bacterial genera included Sphingomonas, Rokubacteriales and Lysobacter, while Orchard B featured Sphingomonas and Acidothermus while beneficial microbes such as Streptomyces and Bacillus were enriched in WRR non-infected (WRR-N) soils. The fungal profiles revealed Trichoderma and Penicillium as potential biocontrol agents enriched in WRR-N soils. Furthermore, dual-culture assays demonstrated that Bacillus, Pseudomonas, Penicillium and Trichoderma isolates inhibited D. necatrix, highlighting their biocontrol potential. Key parameters, such as soil pH and iron (Fe), correlated strongly with microbial composition, suggesting they play an important role in pathogen resilience. DISCUSSION : These findings underscore the complexity of the avocado rhizosphere and its role in managing WRR, offering a foundation for developing integrated disease management strategies to enhance avocado productivity.
Removal of organic biomass in Eucalyptus plantations has a greater impact on fungal than on bacterial networks
(Elsevier, 2025-06) Bose, Tanay; Vivas, Maria; Slippers, Bernard; Roux, Jolanda; Dovey, Steven; Kemler, Martin; Begerow, Dominik; Witfeld, Frederick; Brachmann, Andreas; Wingfield, Michael J.; Hammerbacher, Almuth; tanay.bose@fabi.up.ac.za
Complex and stable soil microbial networks are essential for productivity in plantation forestry, but their response to disturbances from harvesting and replanting is not well understood. This study assessed the impact of treatments designed to mitigate these disturbances on microbial biodiversity and networks in Eucalyptus plantation soils at three South African sites. We used high-throughput sequencing to catalogue fungal and bacterial biodiversity from 108 soil samples across three treatments: (i) retention of harvest residues (retained), (ii) removal of residues (removed), and (iii) removal of residues with added fertilizer (fertilized). Bioinformatic and statistical analyses of the sequence data revealed treatment-specific variations in microbial OTU richness, network structure and taxon associations at order-level. Microbiome richness was highest in ‘retained’ plots, and treatment-specific microbial diversity was evident in both fungal and bacterial communities. Network comparisons revealed that treatments to mitigate disturbances caused by harvesting significantly affected fungal networks but not bacterial networks. Fungal networks in ‘retained’ plots exhibited the highest complexity and stability compared to plots where the entire crop was removed. However, bacterial networks did not show significant differences in network structure among treatments. The associations between fungal and bacterial nodes were consistent in the three treatments, as indicated by similar Jaccard indices. However, distinct fungal hub nodes were found when comparing the 'retained' and 'removed' treatments. These findings highlight that retaining harvest residues enhances microbial richness and stabilizes fungal networks, making it a better strategy for managing soil disturbances than residue removal or fertilization.
Exploring indigenous South African plants as alternative treatments for dermatophytosis : focusing on the antifungal properties and mechanism of action of Searsia lancea
(Elsevier, 2025-07) Madzinga, Murunwa; Malefo, Mammoloro Boitshoko Lydia; Van der Merwe, Chris; De Canha, Marco Nuno; Wadhwani, Ashish; Lall, Namrita; Kritzinger, Quenton; quenton.kritzinger@up.ac.za
Numerous medicinal plants are reported to have activity against dermatophytes, however, there are limited studies providing insights into their mechanism of action, which may be hindering their clinical use. This study aimed to investigate the antifungal activity and toxicity of three South African plants traditionally used to treat skin infections caused by dermatophytes and to investigate the mechanism of action of the most active plant extract. Searsia lancea showed the highest antifungal activity against Microsporum canis (MIC 0.156 mg/mL). Warburgia salutaris and M. comosus showed no toxic effects on HaCaT cells while S. lancea exhibited moderate cytotoxicity. The most active combination of S. lancea combined with M. comosus showed to be non-toxic. Searsia lancea and M. comosus were non-mutagenic at 500 μg/mL. The ethyl acetate partition of S. lancea demonstrated a two-fold increase in activity against Microsporum species while fraction fifteen (F15) exhibited a four-fold increase in activity against T. mentagrophytes. Two compounds in F15 were identified as sakuranetin and gentisic acid, with sakuranetin showing the best activity against T. mentagrophytes. Electron microscopy showed alterations of hyphal surfaces in the form of shrinkage and folding of the plasma membrane (24–48 h) and breakage and leakage of cytoplasmic material (72 h). The RT-qPCR showed significant repression (p < 0.01) of the SSU1 gene of M. canis treated with S. lancea (0.312 mg/mL) after 2 and 7 days. The findings not only support traditional usage of S. lancea but also provide targets of S. lancea's anti-dermatophytic activity.
Appraisal of current and post-mine status of salt mines in a Guinea Savanna ecosystem : implications for natural recovery
(Elsevier, 2025) Akomolafe, Gbenga Festus; Jatau, Dorcas; Iyakwari, Shekwonyadu; Rosazlina, Rusly
Generally, concerns have been raised about increasing mining activities, their impacts on ecosystems and the possibility of site recovery in different parts of the world. This study appraised the status of plant diversity and soil conditions in a popular salt mine of Keana, Nigeria. Ten plots of size 30 m × 20 m were established randomly at each active and abandoned salt mines (SM) and within each plot, five subplots of size 2 m × 2 m were used for the plant diversity assessments. This gave rise to a total of 100 subplots in all the sites. The diversity indices were quantified and dominant species identified. Principal component analysis with Bray-Curtis dissimilarity test was used to establish and compare the species compositions between the sites. Soil samples were collected at four different depths (5, 10, 15 and 20 cm depths) and the chemical properties were determined. Soil analysis revealed high concentrations of heavy metals such as lead, mercury, arsenic and nickel at both sites, but metal concentrations were significantly higher at the active SM using the one-way analysis of variance. The results showed a significantly higher species richness (Taxa_S = 59) and diversity (Simpson index = 0.96 and Shannon index = 3.57; all p < 0.01) at the active SM compared to the abandoned SM (Taxa_S = 32, Simpson index = 0.95 and Shannon index = 3.04). The species compositions between the two sites were significantly different, although with Bray-Curtis value of 0.77 revealing a high shared species compositions. The abandoned SM showed signs of natural recovery, with increased species richness and diversity, and lower metal concentrations. Plant species such as Dactyloctenium aegyptica and Mimosa pudica which were found to be associated with the abandoned SM could be identified as active players in the natural restoration of that site. Some plant species including Hyptis suaveolens and Azadirachta indica that were tolerant to varying high metal levels could be candidates for phytoremediation purposes. The findings of this study highlight the impact of salt mining on plant diversity and metal concentrations in the soil and plants and the potential for natural recovery at abandoned mine sites, insights for post-mining land management and restoration strategies in similar savanna ecosystems.
Insufficient collection capacity and facility, bane of plant taxonomic research in Nigeria
(Canadian Science Publishing, 2025-05) Ajao, Abdulwakeel Ayokun-nun; Akomolafe, Gbenga Festus; Olaniyan, Oluwayemisi Dorcas; Chukwuma, Emmanuel C.; Ugbogu, Alaba O.; Adeonipekun, Peter A.; Ayodele, Abiodun E.; Adeyemi, Sherif B.; Tiamiyu, Bashir Bolaji; Yaradua, Samaila Samaila; Saheed, Sefiu A.; Oladipo, Olaniran Temitope; Oyebanji, Oyetola
This article explores the pivotal role of herbaria in supporting taxonomic research in Nigeria and highlights the need to improve herbarium infrastructure to enhance plant diversity research in the country. Thirteen herbaria are currently recognized in Nigeria on the Index Herbariorum database and collectively house about 260 000 specimens. The Forest Herbarium Ibadan (FHI) is the largest, containing nearly 50% of these specimens. Based on the occurrence data of Nigerian plants on the Global Biodiversity Information Facility (GBIF), the herbaria, namely FHI, ABUH, LUH, NAUH, and UNICAL contributed only 29.9% compared to international herbaria (70.1%). This disparity underscores the need to strengthen the herbarium collection infrastructure in Nigeria. Taxonomic revisionary studies in Nigeria are very scarce as most of the studies have focused on the morpho-anatomical analysis of plant taxa. The poor taxonomic capacity in the country, which is due to insufficiency of collection capacity and trained taxonomists, has been a bane to the compilation of flora of Nigeria and the inability to document the conservation status of threatened plant species, as more than half (66.0%) of Nigeria’s plants published on GBIF have not been evaluated. There is an urgent need for capacity building for plant collection, curation, and taxonomic review.
Special issue : Botanical pesticides for crop protection
(Springer, 2024-12) Kritzinger, Quenton; Dethoup, Tida; quenton.kritzinger@up.ac.za
Crop production forms the foundation of global food security by providing essential nutrients to billions of people and supporting economies worldwide. According to the United Nations, the global population in 2024 is projected to reach 8.2 billion, with expectations to grow to approximately 10.3 billion by the mid-2080s. This population increase places immense pressure on the resources needed for quality crop production. Additionally, climate change has led to global warming, affecting temperature and rainfall patterns, which in turn impacts crop production and plant pest management. This complicates efforts to secure sufficient, safe, and nutritious food to maintain healthy populations.
Establishing African genomics and bioinformatics programs through annual regional workshops
(Nature Research, 2024-08) Sharaf, Abdoallah; Nesengani, Lucky Tendani; Hayah, Ichrak; Kuja, Josiah Ochieng; Mdyogolo, Sinebongo; Omotoriogun, Taiwo Crossby; Odogwu, Blessing Adanta; Beedessee, Girish; Smith, Rae Marvin; Barakat, Abdelhamid; Moila, Acclaim M.; El Hamouchi, Adil; Benkahla, Alia; Boukteb, Amal; Elmouhtadi, Amine; Mafwila, Antoine Lusala; Abushady, Asmaa Mohammed; Elsherif, Assem Kadry; Ahmed, Bulbul; Wairuri, Charles; Ndiribe, Charlotte C.; Ebuzome, Chukwuike; Kinnear, Craig J.; Ndlovu, Deborah-Fay; Iraqi, Driss; El Fahime, Elmostafa; Assefa, Ermias; Ouardi, Faissal; Belharfi, Fatima Zohra; Tmimi, Fatim Zohra; Markey, Fatu Badiane; Radouani, Fouzia; Zeukeng, Francis; Mvumbi, Georges Lelo; Ganesan, Hamilton; Hanachi, Mariem; Nigussie, Helen; Charoute, Hicham; Benamri, Ichrak; Mkedder, Ikram; Haddadi, Imane; Meftah-Kadmiri, Issam; Mubiru, Jackson Franco; Domelevo Entfellner, Jean-Baka Kodjo; Rokani, Joan Bayowa; Ogwang, Joel; Daiga, Jude Bigoga; Omumbo, Judy; Ideozu, Justin Eze; Errafii, Khaoula; Labuschagne, Kim; Komi, Komi Koukoura; Tonfack, Libert Brice; Hadjeras, Lydia; Ramantswana, Madeleine; Chaisi, Mamohale; Botes, Marietjie W.; Kilian, Mariette; Kvas, Marija; Melloul, Marouane; Chaouch, Melek; Khyatti, Meriem; Abdo, Michael; Phasha-Muchemenye, Mmatshepho; Hijri, Mohamed; Mediouni, Mohammed Rida; Hassan, Mohammed Ahmed; Piro, Mohammed; Mwale, Monica; Maaloum, Mossaab; Mavhunga, Mudzuli; Olivier, Nicholas Abraham; Aminou, Oumaima; Arbani, Oumayma; Souiai, Oussema; Djocgoue, Pierre Francois; Mentag, Rachid; Zipfel, Renate Dorothea; Tata, Rolland Bantar; Megnekou, Rosette; Muzemil, Sadik; Paez, Sadye; Salifu, Samson Pandam; Kagame, Samuel Paul; Selka, Sarra; Edwards, Sean; Gaouar, Semir Bechir Suheil; Reda, Shaimaa Roshdy Abdullah; Fellahi, Siham; Khayi, Slimane; Ayed, Soumia; Madisha, Thabang; Sahil, Tulsi; Udensi, Ogbuagu Ugorji; Ras, Verena; Ezebuiro, Victor; Duru, Vincent C.; David, Xavier; Geberemichael, Yonas; Tchiechoua, Yves H.; Mungloo-Dilmohamud, Zahra; Chen, Zhiliang; Happi, Christian; Kariuki, Thomas; Ziyomo, Cathrine; Djikeng, Appolinaire; Badaoui, Bouabid; Mapholi, Ntanganedzeni; Muigai, Anne; Osuji, Julian O.; Ebenezer, ThankGod Echezona
The African BioGenome Project (AfricaBP) Open Institute for Genomics and Bioinformatics aims to overcome barriers to capacity building through its distributed African regional workshops and prioritizes the exchange of grassroots knowledge and innovation in biodiversity genomics and bioinformatics. In 2023, we implemented 28 workshops on biodiversity genomics and bioinformatics, covering 11 African countries across the 5 African geographical regions. These regional workshops trained 408 African scientists in hands-on molecular biology, genomics and bioinformatics techniques as well as the ethical, legal and social issues associated with acquiring genetic resources. Here, we discuss the implementation of transformative strategies, such as expanding the regional workshop model of AfricaBP to involve multiple countries, institutions and partners, including the proposed creation of an African digital database with sequence information relating to both biodiversity and agriculture. This will ultimately help create a critical mass of skilled genomics and bioinformatics scientists across Africa.
Digitalization of precision fertilization in East Africa : adoption, benefits and losses
(Frontiers Media, 2025-03) Fue, Kadeghe Goodluck; Baitu, Geofrey Prudence; Jokonya, Osden; Banwart, Steven; Korsten, Lise
IINTRODUCTION : The rapid digitalization of agriculture in East Africa has spurred the adoption of precision fertilization tools, which optimize nutrient application and enhance crop yields. However, the extent of digital technology adoption, its benefits, and the challenges smallholder farmers face in the region remain unclear. METHODS : A systematic review adhering to PRISMA guidelines assessed the adoption of digital technologies for precision fertilization in East Africa. A comprehensive search of English-language studies published between 2010 and 2024 resulted in fifteen studies that met the inclusion criteria. RESULTS : The review highlights digital solutions that assist smallholder farmers in sustainable resource management, including mobile applications, ICT tools, Variable Rate Application (VRA), and AI/ML technologies. Reported benefits include improved crop productivity, increased economic efficiency, and enhanced environmental sustainability. However, issues with data accuracy, limited access to technology, affordability constraints, and low digital literacy hinder widespread adoption. DISCUSSION : The findings emphasize the need for further research and the development of tailored strategies to enhance digital agricultural practices in East Africa. Addressing socioeconomic and infrastructure challenges is crucial to ensuring equitable access and maximizing the effectiveness of digital precision fertilization tools. This review provides valuable insights to support stakeholders in developing sustainable, data-driven agricultural frameworks to improve regional food security.
Flavonoids and anthocyanins in seagrasses : implications for climate change adaptation and resilience
(Frontiers Media, 2025-01) Botes, Jana; Ma, Xiao; Chang, Jiyang; Van de Peer, Yves; Berger, David Kenneth
Seagrasses are a paraphyletic group of marine angiosperms and retain certain adaptations from the ancestors of all embryophytes in the transition to terrestrial environments. Among these adaptations is the production of flavonoids, versatile phenylpropanoid secondary metabolites that participate in a variety of stress responses. Certain features, such as catalytic promiscuity and metabolon interactions, allow flavonoid metabolism to expand to produce novel compounds and respond to a variety of stimuli. As marine environments expose seagrasses to a unique set of stresses, these plants display interesting flavonoid profiles, the functions of which are often not completely clear. Flavonoids will likely prove to be effective and versatile agents in combating the new host of stress conditions introduced to marine environments by anthropogenic climate change, which affects marine environments differently from terrestrial ones. These new stresses include increased sulfate levels, changes in salt concentration, changes in herbivore distributions, and ocean acidification, which all involve flavonoids as stress response mechanisms, though the role of flavonoids in combatting these climate change stresses is seldom discussed directly in the literature. Flavonoids can also be used to assess the health of seagrass meadows through an interplay between flavonoid and simple phenolic levels, which may prove to be useful in monitoring the response of seagrasses to climate change. Studies focusing on the genetics of flavonoid metabolism are limited for this group, but the large chalcone synthase gene families in some species may provide an interesting topic of research. Anthocyanins are typically studied separately from other flavonoids. The phenomenon of reddening in certain seagrass species typically focuses on the importance of anthocyanins as a UV-screening mechanism, while the role of anthocyanins in cold stress is discussed less often. Both of these stress response functions would be useful for adaptation to climate change-induced deviations in tidal patterns and emersion. However, ocean warming will likely lead to a decrease in anthocyanin content, which may impact the performance of intertidal seagrasses. This review highlights the importance of flavonoids in angiosperm stress response and adaptation, examines research on flavonoids in seagrasses, and hypothesizes on the importance of flavonoids in these organisms under climate change.
Growth analysis of pearl millet genotypes grown under different management practices
(MDPI, 2025-03) Ausiku, Petrus Ausiku; Annandale, John George; Steyn, Martin Joachim; Sanewe, Andrew; u14431786@tuks.co.za
Pearl millet is a cereal crop vital for food security in Africa and Asia. It is widely adapted for dual-purpose production, providing grain for human consumption and fodder for livestock, particularly during dry seasons. This study aimed to evaluate three dual-purpose pearl millet genotypes from Namibia and South Africa while exploring prospects for future production practices. Growth analysis is essential for quantitatively assessing crop growth, development, and production. A growth analysis study was conducted by collecting and evaluating weather data, water use efficiency, and crop growth parameters that are valuable for modelling, allowing for observing and quantifying strengths and weaknesses between varieties for food and fodder or as dual-purpose varieties. The analysis focused on water use, plant height, fractional radiation interception, panicle number, tiller number, flowering date, stem diameter, panicle length, dry matter distribution, harvest index, grain yield, and panicle diameter, under well-watered, supplementary irrigation, and rainfed conditions. The landrace achieved a higher yield under well-watered conditions than the hybrid and improved varieties. The hybrid pearl millet produced a greater fodder yield than the improved short variety in well-watered and water-limited treatments. The improved variety suits grain production, whereas the landrace and hybrid are more suitable for dual-purpose production. The landrace performed well in rainfed and irrigated situations across the three seasons. The landrace (Kantana) recorded the highest grain yield (1.01 kg m−2), followed by the hybrid (Agrigreen) (0.97 kg m−2), while the improved variety (Kangara) had the lowest grain yield (0.74 kg m−2).
Investigating abiotic and biotic parameters associated with gradually declining Valencia citrus trees in South Africa
(Southern Cross Publishing, 2024-02-29) Pretorius, Mathys C.; Labuschagne, Nico; Daneel, M.; Raath, Pieter; Cadet, P.; McLeod, Adele; nico.labuschagne@up.ac.za
The current study determined if a combination of biotic and abiotic parameters could differentiate Citrus sinensis trees (three categories based on visual tree canopy status) with root disease-related decline symptoms in two citrus orchards. Two experimental sites, containing a range of healthy and different stages of decline trees, were randomly selected. Three decline category trees were selected with abiotic and biotic parameters associated with decline measured. Principal component analyses of 41 soil, leaf, root and trunk associated parameters ordered the category 1 to 3 trees chronologically on the factorial plan for both orchards. However, the parameters only described a low level of the variability. Only the healthy (category 1) and more diseased (category 3) trees were studied further. Soil electrical conductivity and leaf %N, were the only parameters differing significantly between the two categories in both orchards, but both parameters were significantly higher in category 3 trees in orchard 1 whereas the opposite was true for orchard 2 with significantly higher values in category 1 trees. In the more severely declining MP1 orchard, parameters differing significantly between the two categories included soil Na, cation exchange capacity and leaf Fe, B, Mo and Zn. In orchard MP2, parameters were soil %C, soil citrus nematodes, leaf size and leaf %Na and %Mg. Discriminant analysis indicated that leaf parameters were more specifically associated with decline. Leaf nutrient status can possible be an additional process to indicate decline.
Dispersal potential does not predict recent range expansions of sub-Antarctic plant species
(Springer, 2024-05) Mazibuko, Nompilo; Greve, Michelle; Le Roux, Peter Christiaan
Dispersal influences many key aspects of plant ecology at both fine- and broad scales. However, dispersal events are challenging to quantify as they are difficult to observe and measure accurately, despite the importance of understanding species’ dispersal capacity. In this study, we quantified dispersal estimates for the dominant vascular flora of sub-Antarctic Marion Island, using a mechanistic model to estimate dispersal potential via anemochory and standardized experiments that simulate dispersal events via zoochory, human activity, and thalassochory, to test if dispersal capacity correlates to contemporary range expansion of the island’s native and alien species. Our results demonstrate the broad range of dispersal potential in the island’s flora and represent the first quantification of the dispersal potential (via multiple vectors) of the dominant vascular flora in the sub-Antarctic. Dispersal potential was not related to range expansion rates of native or alien species, suggesting that other mechanisms are responsible for the variation observed in species range expansion rates. Although this finding contradicts expectations and evidence from some other studies, it is consistent with research conducted in alpine regions (which may be climatically and physiognomically similar to this sub-Antarctic study site) where factors such as demography and competition are more important predictors of species range expansion than their dispersal ability, dispersal syndromes, or dispersal-related traits.
Advancements in Spongospora subterranea : current knowledge, management strategies, and research gaps
(Springer, 2024-12) Strydom, R.F.; Wilson, C.R.; Tegg, R.S.; Balendres, M.A.; Van der Waals, Jacqueline Elise
Powdery scab was first documented on locally sampled potatoes in Braunschweig, Germany. A hundred and eighty-one years later, the disease has spread globally to most potato-producing regions and is considered one of the most destructive potato diseases. Here, we review the knowledge of powdery scab and causative agent, Spongospora subterranea f. sp. subterranea, highlighting research progress made in the last 7 years. Much work has been done to increase our understanding of how zoospores respond to their environment (e.g. root exudates, Ca2C signalling, and root metabolites) and the management of the disease by chemical and biological control agents. Recent research has utilised omics approaches — metabolomics, proteomics, and genomics — to gain a deeper understanding of the host–pathogen interaction in the powdery scab pathosystem. The management of powdery scab can be achieved using a combination of strategies that include (1) the planting of resistant potato varieties, (2) strategies that avoid disease (field selection and planting date), those that (3) reduce initial soil inoculum (crop rotation, organic soil amendments, and soil fumigation), and (4) in-crop approaches (soil chemical applications, biological control, proper field, fertility, crop, irrigation management, and crop sanitation). Lastly, we discuss research gaps for future research, including the disease’s interaction with other potato diseases that may be impacting disease expression and opportunities to enable a greater understanding of the powdery scab pathosystem.
Exceptional and enigmatic southern African Oxalis – a review
(Elsevier, 2025-07) Dreyer, Laurette; Oberlander, Kenneth Carl
Oxalis is a diverse, morphologically variable, and biologically unusual member of South Africa’s flora, but has seen surprisingly little research focus despite its relevance to multiple ecological and evolutionary questions. In this review we sketch what makes this lineage exceptional in terms of what is known, and enigmatic in terms of what still needs attention, through the lens of three decades of research focus on our part. Our hope is to focus attention on, and stimulate research interest in, this extraordinary genus.

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