The impact of DCA storage on fruit quality: a comparison between organic ‘Gala’ and ‘Honeycrisp’ apples
Sadat Amankona
Sadat Amankona is a Ph.D. candidate in the postharvest systems lab at Washington State University – Tree Fruit Research and Extension Center. His research focuses on using non-chemical strategies to optimize the storage of organic apples in the Pacific Northwest.
There has been a surge in the demand for organic apples in the USA with Washington State supplying over 90% of them. ‘Gala’ and ‘Honeycrisp’ apples are currently the top two cultivars. Despite the year-round demand for organic apples, storage challenges continue to impact fruit quality due to prohibitions on the use of synthetic chemicals. Dynamic controlled atmosphere (DCA) storage is emerging as a promising chemical-free alternative to optimize fruit quality and minimize physiological disorders.
In this study, the main objective was to evaluate the effectiveness of DCA based on the respiratory quotient (RQ) compared to controlled atmosphere (CA) and regular atmosphere (RA) storage for organic ‘Gala’ and ‘Honeycrisp’ apples for two consecutive years (2022-2024). Fruit samples were stored for up to 9 months and an additional 2 or 4 weeks in regular air to mimic transit and presentation on the retail shelf. Fruit quality parameters [firmness and titratable acidity (TA)], and physiological disorders were evaluated after 7 days at 20°C.
Overall, the results showed cultivar-specific responses. For ‘Gala’, DCA fruit was both firmer (≥3 lb) and the TA was higher (≥0.2% malic acid), outperforming CA and RA. For ‘Honeycrisp’, firmness was not significantly different across treatments, but DCA showed better TA retention, particularly in year 2 (2023/24). DCA also reduced internal browning and shriveling disorders in ‘Gala’. However, Honeycrisp’ showed a greater incidence of bitter pit while soft scald remained below 5% in all treatments.
These findings suggest that DCA is a viable postharvest treatment for optimizing the storage and quality of organic apples, although its effectiveness appears to be cultivar-dependent and benefits ‘Gala’ more than ‘Honeycrisp’. Further research is necessary to assess the consistency of the impact of DCA for fruit produced under varying seasons and environmental conditions.
Sadat Amankona won the ISHS Young Minds Award for the best poster presentation at the XIV International Controlled and Modified Atmosphere Research Conference in USA in May 2025.
Contact: Sadat Amankona, Washington State University, Tree Fruit Research and Extension Center, 1100 N. Western Avenue, Wenatchee, Washington, 98801, USA, e-mail: sadat.amankona@wsu.edu or sadatsavvy@gmail.com
The article is available in Chronica Horticulturae.
Study on high yields of potato microtubers formed by long-day conditions using temporary light interruption treatment
Ryohei Kobayashi
In Japan, tubers of approximately 10 g are generally used as seed potatoes. Replacing these with disease-free 1-3 g microtubers (MTs) has been shown to have a significant and positive impact on yield. However, for this alternative to be more cost effective, it is necessary to increase the number of MTs produced. At the molecular level, under short day (SD) conditions, SELF-PRUNING 6A (stSP6A) is expressed in the leaves and transported to the stolons where it induces tuber formation. This process requires the expression and destabilization of CONSTANS-like 1 (stCOL1) during the dark period, which suppresses the expression of the tuberization repressor SELF-PRUNING 5G (stSP5G). By contrast, under LD conditions, stabilization of stCOL1 enhances stSP5G expression, thereby inhibiting tuberization. To promote tuberization under LD conditions, we investigated the regulation of stCOL1 through light-quality treatments. For this study, we found that day-break lighting (DB) using far red irradiation for 10 min followed by 3 h of darkness, beginning 1 h after the onset of the light period, effectively suppressed stCOL1 expression. However, the expression level of stSP6A under DB was lower than that under SD, suggesting the need for further improvements to enhance yield. This study examined the effects of combining DB and SD treatments on MT formation in a plant factory with artificial lighting (PFAL). Alternating SD treatment at one-week intervals under LD conditions reduced the yield of MTs compared with that under DB treatment alone. In contrast, combining DB and SD treatments at one-week intervals produced the highest yield of MT, with up to 80 MTs per plant, surpassing the yields obtained with either DB or SD treatment alone. These findings provide valuable insights that may contribute to establishing novel strategies for seed potato production in PFAL systems.
Ryohei Koyabayashi won the ISHS Young Minds Award for the best poster presentation at the IX International Symposium on Seed, Transplant and Stand Establishment of Horticultural Crops and III International Symposium on Vegetable Grafting in Greece in June 2025.
Contact: Ryohei Kobayashi, Graduate School of Agriculture, Tamagawa University, 6-1-1 Tamagawagakuen, Machida, Tokyo, 194-8610, Japan, e-mail: tv3f24221@stu.tamagawa.ac.jp
The article is available in Chronica Horticulturae.
The effects of acute gamma irradiation on Malaysian aromatic rice cultivar ‘MRQ104’: implications for agronomic performance and ornamental potential
Aliif Ihsaan Akmal Shukri
Aliif Ihsaan Akmal Shukri is an agronomist/geneticist specializing in the induced mutation breeding of rice. He is a PhD candidate from the Faculty of Plantation and Agrotechnology, Universiti Teknologi MARA, Malaysia. His current project focuses on the gamma mutation breeding of Malaysian aromatic rice ‘MRQ104’, aiming to develop a new mutant variety with higher yield, better agronomic performance, enhanced aromatic properties and greater ornamental potential. In a greenhouse, ~6000 seeds (M1 generation) of ‘MRQ104’ were treated with 5 different acute gamma doses: 0 Gy (control), 100, 150, 200, 250 and 300 Gy. M1 progenies with stable or improved quality were then cultivated in designated rice fields as M2 generation and subsequently into M3. Final results demonstrated a marked increase in yield of 15-33% per hectare for the irradiated groups. The flowering and maturity period for all irradiated groups was 3-7 days earlier than the control group. A wide spectrum in plant height could also be observed between groups, with the 300 Gy treatment growing 20 cm taller than the unirradiated seeds. While the main purpose was to develop a staple food crop, the findings also opened the potential for ornamental rice species. The distinct differences in height could potentially be manipulated to produce rice art (Tanbo), which is widely practiced in Japan. The application of rice lines from at least two groups (i.e. control and 300 Gy) offered the greatest potential for eco-tourism (rice art).
Aliif Ihsaan Akmal Shukri won the ISHS Young Minds Award for the best oral presentation at the III International Symposium on Tropical and Subtropical Ornamentals in Malaysia in July 2025.
Contact: Aliif Ihsaan Akmal Shukri, Faculty of Plantation & Agrotechnology, Universiti Teknologi MARA (UiTM), Cawangan Melaka Kampus Jasin, 77300, Merlimau, Melaka, Malaysia, e-mail: aliifihsaan@yahoo.com
The article is available in Chronica Horticulturae.
The molecular mechanism of gibberellin regulates sex differentiation in Corylus heterophylla × Corylus avellana
Suilin Zhang
Hazelnut, one of the four major nut crops in the world, has significant economic value. Hazelnuts have unisexual flowers, with both male and female flowers on the same plant. However, the ratio of female to male is very low, which seriously affects their yield. This study found that exogenous GA3 increased the male-to-female ratio of hybrid hazelnuts（Corylus heterophylla × Corylus avellana）by increasing the number of male flower buds. Conversely, the exogenous application of paclobutrazol increased the ratio of female to male flowers. Exogenous GA3 promotes the expression of ChaLFY and ChaAP1, which inhibits the expression of ChaFT, but has no significant effect on the expression of ChaSOC1. Exogenous paclobutrazol inhibits the expression of ChaLFY, promotes the expression of ChaFT and ChaSOC1, but had no significant effect on the expression of ChaAP1. In this study, three ChaDELLA genes were identified from the genome of C. heterophylla × C. avellana, namely Cor0144260.1, Cor0053250.1, and Cor0117260.1. Analysis of the protein interaction network revealed that the ChaDELLA protein could interact with the ChaLFY and ChaSOC1 proteins. An analysis of the upstream and downstream regulatory networks revealed that the ChaDELLA transcription factor can bind to the promoter regions of the flowering genes ChaLFY, ChaFT, ChaAP1, and ChaSOC1, and may regulate the sex differentiation of C. heterophylla × C. avellana by regulating the expression of the flowering genes. This study aimed to lay a theoretical foundation for revealing the mechanism by which gibberellin is involved in regulating the flowering regulation of hybrid hazelnuts of the common European variety, and to offer suggestions for artificially regulating the ratio of male to female flowers and increasing yield.
Suilin Zhang won the ISHS Young Minds Award for the best poster presentation at the XI International Congress on Hazelnut in August 2025.
Contact: Suilin Zhang, State Key Laboratory of Efficient Production of Forest Resources, Key Laboratory for Silviculture and Conservation of Ministry of Education, Beijing Forestry University, Beijing 100083, China, e-mail: lg20170404@bjfu.edu.cn
The article is available in Chronica Horticulturae.
Water stress effect on eco-physiological parameters of pistachio trees
Valeria Imperiale
The pistachio (Pistacia vera L.) is a highly resilient crop, capable of tolerating several abiotic stresses, including water shortage. Due to this, it is traditionally cultivated in dry conditions in the Mediterranean region, including Sicily. However, the lack of irrigation often causes physiological limitations and agronomic issues, such as reduced CO2 assimilation, alternate bearing, poor nut quality, and reduced yields. Even though pistachios are drought-tolerant, maintaining a sufficient water supply is crucial to sustain high productivity. This study aimed to investigate the response of mature pistachio trees to different water supply levels to improve irrigation management in Sicilian orchards. The experiment was carried out in the Caltanissetta area on trees of the ‘Bianca’ cultivar grafted onto Pistacia terebinthus L. Three water regimes were compared: rainfed (T0), 50 mm ha-1 (T1), and 100 mm ha-1 (T2), applied during fruit development, from June to August 2024. The physiological measurements included maximum net photosynthesis rate (Amax), stomatal conductance (gs), intrinsic water use efficiency (WUEi), and midday stem water potential (SWP). Although the water supplied was very limited in T1 and T2, it enabled the trees to sustain a higher water status than the rainfed ones throughout the entire growing season. Stomatal conductance and assimilation rates were also higher in the irrigated treatments, confirming that supplemental irrigation reduces stress during the production season. However, the opposite situation was observed in terms of water use efficiency. A sharp decline in photosynthesis and stomatal conductance occurred when the SWP dropped below -1.5 MPa, indicating the onset of severe water stress conditions. Despite these physiological benefits, no significant differences were observed among treatments in yield parameters, such as nut number and kernel weight per tree in the first year. This study demonstrates that small amounts of water were beneficial in enhancing the physiological performance of the plants. However, to assess the effects on production, it will be necessary to observe the physiological responses over a longer term, considering also the species’ alternate bearing behavior.
Valeria Imperiale won the ISHS Young Minds Award for the best poster presentation at the I International Symposium on Temperate Tree Nuts: from Agroecologically Sustainable to Organic Production in Italy in August 2025.
Contact: Valeria Imperiale, University of Palermo, Department of Agricultural, Food and Forest Sciences, Viale delle Scienze, Ed 4, 90128 Palermo, Italy, e-mail: valeria.imperiale@unipa.it
The article is available in Chronica Horticulturae.
Stomatal traits in pecan [Carya illinoinensis (Wangenh.) K. Koch]: varietal differences and seasonal adaptations under Mediterranean conditions
Alessandro Pesole
Pecan [Carya illinoinensis (Wangenh.) K. Koch] is gaining increasing attention in Mediterranean regions as a promising alternative crop for diversifying nut production and coping with climate variability. Despite its recognized nutritional and agronomic value, limited information exists on its morphological and physiological behavior under Mediterranean conditions. To address this gap, a two-year trial (2019-2020) was conducted to characterize selected leaf traits in different cultivars.
The study was carried out at the repository of the Department of Soil, Plant and Food Sciences, University of Bari ‘Aldo Moro’, located at the “Martucci” experimental and educational center in Valenzano (Bari province, Puglia region, Italy). Ten pecan cultivars were evaluated for two parameters: leaf area (LA) and stomatal density (SD). Leaf samples collected during the growing season were analyzed microscopically for SD, while LA was determined using image-based techniques. Data were statistically analyzed through analysis of variance (ANOVA) followed by Ryan-Einot-Gabriel-Welsch and Quiot (REGWQ) post hoc tests to identify significant differences among cultivars.
Results revealed marked variability among cultivars under the pedo-climatic conditions of the Puglia region. ‘Cherokee’ and ‘Choctaw’ displayed the largest leaves, with mean areas of 454.13 mm2, whereas ‘Cape Fear’ had the smallest (215.56 mm2). In contrast, stomatal density was highest in ‘Stuart’ and ‘Cape Fear’ (589.58 and 566.66 stomata mm-2, respectively) and lowest in ‘Peruque’ and ‘Cherokee’ (427.08 and 444.79 stomata mm-2). The contrasting combinations of LA and SD suggest that pecan genotypes may adopt different adaptive strategies to a Mediterranean climate. For instance, larger leaves with fewer stomata, as in ‘Cherokee’, may indicate a strategy to maximize photosynthetic surface while reducing water loss, whereas smaller leaves with higher stomatal density, as in ‘Cape Fear’, could encourage faster gas exchange but imply greater drought sensitivity.
Overall, the data supports the existence of cultivar-specific morphological patterns that may influence photosynthetic efficiency and tolerance to water limitations under Mediterranean conditions. These results provide a first basis for identifying pecan cultivars best adapted to Mediterranean environments. Future research will aim to link stomatal and foliar traits with physiological performance, yield stability, and nut quality, thereby enhancing the role of pecan as a resilient crop in climate-challenged regions.
Alessandro Pesole won the ISHS Young Minds Award for the best poster presentation at the VI International Symposium on Pomegranate and Minor Mediterranean Fruits in Italy in September 2025.
Contact: Alessandro Pesole, Department of Soil, Plant and Food Sciences, University of Bari ‘Aldo Moro’, Via Giovanni Amendola 165/A, 70126 Bari (BA), Italy, e-mail: a.pesole7@phd.uniba.it
The article is available in Chronica Horticulturae.