Study on the role of endogenous ethylene in highbush blueberry (V. corymbosum) fruit ripening
Claudio Ponce
Blueberries are an important soft fruit crop, valued for their nutritional properties. Global production is rapidly expanding with the United States leading the market. Achieving optimal market value depends heavily on precise harvest timing, which is often regulated through the use of plant bioregulators (PBRs). However, the effective use of these compounds requires a clear understanding of fruit ripening physiology, which at this point in time is not fully resolved. While some studies describe the species as climacteric, others describe blueberries as non‑climacteric. Most research on ethylene has relied on the postharvest application of ethephon (an ethylene-releasing compound), whereas the contribution of endogenous ethylene during preharvest ripening has not yet been evaluated. In this study, we investigated the role of endogenous ethylene in blueberry ripening to support production management. Gas chromatography measurements showed that the interspecific hybrid Vaccinium corymbosum ‘O’Neal’ produces low but detectable ethylene levels that rise at the onset of ripening. Preharvest application of 1‑MCP, an ethylene inhibitor, delayed color development by reducing anthocyanin accumulation and slowed the decline in acidity, yet did not alter ethylene emission either alone or when combined with an ethylene agonist. Additionally, conferring ethylene insensitivity through transient overexpression of Arabidopsis etr1‑1 mutant allele in berries produced effects similar to 1‑MCP treatment. Overall, our findings indicate that endogenous ethylene participates in blueberry fruit ripening but does not operate through a climacteric‑type autocatalytic system biosynthesis. These results offer valuable guidance for the strategic use of PBRs in blueberry fruit production.
Claudio Ponce won the ISHS Young Minds Award for the best oral presentation at the XV International Symposium on Plant Bioregulators in Fruit Production in USA in June 2025.
Contact
Claudio Ponce, Laboratory of Pomology, Graduate School of Agriculture, Kyoto University, Kyoto, 606-8502, Japan, e-mail: ponce.miguel.77w@st.kyoto-u.ac.jp
Comparison of Punica granatum L. leaf area index determined using in situ and remote sensing techniques
Raesibe Kgaphola
Leaf area index (LAI) is a crucial parameter for assessing vegetation health and canopy structure in pomegranate (Punica granatum L.) orchards. This study examined the application of remote sensing (PySEBAL) using Landsat 8 images and ground-based measurements (AccuPAR LP-80 ceptometer) to determine LAI and its influence on the fractional interception of light in Wellington, Western Cape Province, South Africa. The data collected was categorized by canopy development stages into seasonal trends, compared and validated across three periods (September 2022 to March 2023, April to May 2023, and July to October 2023) to assess model accuracy and reliability using Statgraphics Centurion Version XV for regression analysis. The relationship between remote sensing-derived LAI and in-situ AccuPAR LP-80 modelled LAI was linear and showed less complexity than polynomial trends at the start of the growing season, likely due to reduced variation in vegetative growth. In contrast, weaker linear patterns emerged in the late season, suggesting increased variability associated with the decline in LAI as the canopy transitioned from vegetative to reproductive stages. Overall, model performance demonstrated accurate LAI estimations over extended periods. However, weak to moderate correlations with in-situ measurements were observed, with the highest regression value of 78.9% during specific seasonal transitions. The research was supported and funded by the Water Research Commission and the National Research Foundation as part of the pomegranate orchard water use and productivity project.
Raesibe Kgaphola won the ISHS Young Minds Award for the best oral presentation at the VI International Symposium on Pomegranate and Minor Mediterranean Fruits in Italy in September 2025.
Contact
Raesibe Kgaphola, University of the Free State, 205 Nelson Mandela Drive, 9300 Bloemfontein, South Africa, e-mail: raesibe.lebogang@gmail.com
A feedback and feedforward IDSS based on wireless sensor networks and 5G-satcom applied in precision viticulture
Emanuele Dichio
This study details the development and field validation of an integrated feedback-feedforward irrigation decision support system (IDSS) for precision viticulture, based on a LoRa wireless sensor network (WSN) and a hybrid 5G-satellite communication framework. The system aims to provide reliable, real-time monitoring and autonomous irrigation management in rural areas with limited terrestrial connectivity.
The hardware was developed at the Agro-Hydrological Sensing and Modelling Laboratory (University of Pisa, Italy) and deployed in two commercial vineyards in Lucca (Tuscany, Italy). Custom ESP32-based nodes, integrated with LoRa (SX1276) modules on open-source PCBs, collect soil-plant-atmosphere data and control electrovalves. Sensors include FDR probes for soil water content (SWC), infrared thermometers for canopy temperature, atmometers for reference evapotranspiration, pressure and flow sensors, and water level/conductivity probes. Each node is solar-powered and arranged in a star-of-stars LoRa topology, with data transmitted to a gateway and then forwarded via Wi-Fi to a 5G customer premises equipment (CPE). A satellite backhaul connects local processing units to a centralised cloud platform.
The IDSS integrates both feedforward (FFc) and feedback (FBc) control methods. The feedforward part uses an FAO-56 soil water balance model with crop coefficient (Kc) and water stress coefficient (Ks). Meanwhile, the feedback part depends on real-time soil water content (SWC) thresholds and the crop water stress index (CWSI), which is obtained from canopy temperature data. An algorithm written in Python automatically detects the upper (field capacity) and lower (critical) soil moisture thresholds by smoothing signals and analyzing derivatives, supporting adaptive irrigation scheduling.
Data visualisation and system management are performed using a cloud-based Grafana platform. Field results from June 2025 showed a strong correlation between SWC and CWSI trends, confirming the system’s capability to detect water stress and assess irrigation effectiveness.
This research was funded by the European Space Agency (ESA) under the 5G-HOSTS-SAT project “5G HUB Over-the-Air Vertical Segment Validations.”
Emanuele Dichio won the ISHS Young Minds Award for the best oral presentation at the XI International Symposium on Irrigation of Horticultural Crops in Australia in January 2026.
Contact
Emanuele Dichio, AgroHydrological Sensing and Modelling Laboratory (AgrHySMo), Department of Agriculture, Food and Environment (DAFE), University of Pisa, Via del Borghetto 80, 56124, Pisa (PI), Italy, e-mail: emanuele.dichio@phd.unipi.it
Water relations and growth of rootstock‑scion combinations in pome and stone fruit trained as narrow orchard
Harsimran Singh
Harsimran Singh is a first year PhD student working on the national project ‘Narrow Orchard Systems for Future Climates’ funded by Agriculture Victoria and Hort Innovation Australia and delivered via The University of Queensland (Australia). One of the components of his research focuses on evaluating water relations in different rootstock-scion combinations of pome and stone fruits planted as narrow orchard systems (NOS).
The Goulburn Valley is an important Australian fruit growing region, where labour shortages and high operational costs continue to be a major hurdle, pushing growers towards systems like NOS. The main characteristics of NOS are i) narrow canopies, with ii) multiple closely spaced upright leaders and iii) narrow inter-rows. These systems aim to create compact, highly productive canopies that can support automation of orchard tasks. Understanding the behaviour of rootstock-scion combinations can help in meeting the desired expectations in these systems.
In this study, cherries, nectarines, plums, apples and pears, grafted onto three rootstocks and spaced at 2×2 m, were evaluated for water relations [stomatal conductance (gs), transpiration rate (E) and midday stem water potential (Ψstem)], canopy light interception, upright length, trunk development, and chlorophyll concentration in spring and summer 2025-26.
The apple rootstock M9 showed a higher level of water stress compared to other rootstocks. CG202 had larger canopies and displayed reduced gs and E. For cherry, Gisela 12 reduced growth during the stress period and recovered its gs and E slower than both Stallion and Krymsk 5. Rootpac 40 maintained the best water status and strongest growth before and after stress for nectarine, while Rootpac 20 operated at very low gs and E under drought. For plum, Myrobalan H29C produced the highest upright growth during stress and recovery phase, whereas Rootpac R exhibited better water status at peak stress. Pear rootstocks were less variable overall, though QA consistently maintained a higher Ψstem than other rootstocks.
Harsimran Singh won the ISHS Young Minds Award for the best poster presentation at the XI International Symposium on Irrigation of Horticultural Crops in Australia in January 2026.
Contact
Harsimran Singh, Tatura SmartFarm, Agriculture Victoria, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Australia, e-mail: harry.singh@agriculture.vic.gov.au or harsimran.singh@uq.edu.au
Chemical profiling of two Eriocephalus essential oils and their antifungal potential against Diaporthe infecunda and Alternaria alstroemeriae
Mahlatse Morena
Mahlatse Morena is a Master’s candidate at the University of Johannesburg, affiliated with the Postharvest and Agroprocessing Research Centre, South Africa. Her research focuses on the development of sustainable and plant-based strategies to reduce postharvest deterioration of fresh produce, with a focus on tomatoes. This study investigated the antifungal activity and chemical composition of essential oils derived from Eriocephalus tenuipes and Eriocephalus punctulatus, two species of highly aromatic shrubs with antimicrobial and antioxidant properties. However, despite their potential, these species remain underexplored. Therefore, this study specifically focused on their composition and efficacy against Diaporthe infecunda and Alternaria alstroemeriae, isolated from tomato fruits. Gas chromatography-mass spectrometry (GC-MS) was applied to determine the volatile composition of the two essential oils, which revealed distinct phytochemical profiles between the two species. Chemical composition analysis demonstrated various bioactive constituents, including compounds widely known for their antimicrobial activity. Eriocephalus tenuipes displayed a more diverse chemical composition with a higher proportion of oxygenated monoterpenes, including 1,8-cineole, artemisia ketone and artemisia alcohol. In contrast, Eriocephalus punctulatus’ chemical profile was dominated by only a few major compounds such as p-cymene, linalyl acetate and butanoic acid. The antifungal activity of both essential oils was conducted in vitro at concentrations of 2000, 3000 and 4000 ppm. The antifungal test showed that the essential oils effectively reduced the mycelial growth of Diaporthe infecunda and Alternaria alstroemeriae. Eriocephalus tenuipes had inhibitory activity above 95%, whereas Eriocephalus punctulatus had 67.96% against Diaporthe infecunda. Regarding Alternaria alstroemeriae, Eriocephalus tenuipes still exhibited superior inhibition than Eriocephalus punctulatus. These findings highlight that Eriocephalus essential oils have great promise as natural alternatives to synthetic fungicides in postharvest disease management. The study contributes to advancing environmentally friendly preservation methods for reducing postharvest losses and maintaining produce quality. Future studies will examine optimising application strategies, such as vapour-phase distribution and integration into packaging systems, as well as efficacy under realistic storage conditions.
Mahlatse Morena won the ISHS Young Minds Award for the best oral presentation at the IV International Symposium on Beverage Crops in South Africa in March 2026.
Contact
Mahlatse Morena, University of Johannesburg, Auckland Park, 2092 Gauteng Johannesburg, South Africa, e-mail: mahlatse.morena2001@gmail.com
Pectic polysaccharide from Opuntia ficus-indica: microwave extraction and comparison of cladode part
Priscilla Livhuwane Mukwevho
Priscilla Livhuwane Mukwevho is a PhD candidate at the Postharvest and Agroprocessing Research Centre at the University of Johannesburg, South Africa. Her research is focused on the development of a synbiotic product utilizing pectic polysaccharide-rich Opuntia ficus-indica (OFI) for the management of gut health problems. Pectic polysaccharide (PP) is an important prebiotic in synbiotics, but a sustainable extraction method that produces high production yield and functional quality is required. This study investigated the impact of microwave pretreatment power levels (360, 450 and 900 W) on the yield and functional properties of citric acid acidified water-extracted pectin from various OFI cladode components (peel, mucilage and insoluble fibre), including yellowness, moisture content, solubility, degree of esterification (DE), and water holding capacity (WHC). Results showed that microwave power and OFI cladode parts significantly impacted the yield and quality of PP. Moisture content and the DE decreased with increasing microwave power, with fibre and mucilage exhibiting the lowest moisture content and highest DE, respectively. Conversely, production yield increased with higher microwave power, with mucilage achieving the highest yield across all power levels. Yellowness decreased as power increased from 360 to 450 W, before slightly increasing at 900 W, with mucilage maintaining the highest yellowness. Solubility and WHC increased between 360 and 450 W, followed by a slight decrease at 900 W. These results demonstrate that microwave pretreatment of mucilage at low-to-moderate power levels (360-450 W) can produce pectin polysaccharides with desirable quality and quantity for synbiotic product formulation.
Priscilla Livhuwane Mukwevho won the ISHS Young Minds Award for the best poster presentation at the IV International Symposium on Beverage Crops in South Africa in March 2026.
Contact
Priscilla Livhuwane Mukwevho, Postharvest and Agroprocessing Research Centre & South African Research Chairs Initiative in Sustainable Preservation and Agroprocessing Research, Department of Botany and Plant Biotechnology, University of Johannesburg, P.O. Box 524, Auckland Park, Johannesburg 2006, South Africa, e-mail: priscillamukwevho@gmail.com