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2025 Student Flash Talks Viticulture
June 18, 2025 – 4:30pm – 5:15pm
VITICULTURE
Some student authors have been assigned oral, 3.25-minute Flash Talks. These “flash” presentations will provide additional opportunities for interaction between conference attendees and student researchers.
Flash Talks will take place on Wednesday, June 18, 4:30 pm – 5:30 pm, at the Portola Hotel in Monterey, California.
Moderator:
Lise Asimont, Foley Family Wines, California
Speakers:
Guadalupe Partida | Luca Pallotti | Vincenzo Cianciola | Alessandro De Rosa | Marco Saldivar |
Xavier Rideout | William Whalen | Luca Brillante*
Strategies to Mitigate Heat Stress
and Delay Berry Ripening in Grape Production Amid Climate Change
Guadalupe Partida, Luca Pallotti, Vincenzo Cianciola, Alessandro De Rosa, Marco Saldivar, Xavier Rideout, William Whalen and Luca Brillante*
*Department of Viticulture and Enology, California State University Fresno, 2360 E Barstow Ave, Fresno, CA, 93740, lucabrillante@csufresno.edu
Global warming increasingly threatens grape production in regions like California’s Central Valley. Late-season practices aimed at reducing photosynthetic efficiency may enhance vine resilience and delay ripening. Over three years, this study compared an untreated control (C) with applications of pinolene (P) and diatomaceous earth (D), as well as a novel shoot twisting (T) treatment designed to mimic the benefits of topping while preventing excessive cluster exposure. Measurements of leaf area, light interception, midday stem water potential, and gas exchange were collected throughout each growing season. Berry ripening progression and grape production at harvest were also assessed. Shoot twisting led to desiccation of the upper portion of the shoot, reducing leaf area while maintaining low irradiance in the fruiting zone. Stem water potential data indicated that D, and particularly T, alleviated stress conditions, while P negatively affected vine water status. D significantly influenced gas exchange, increasing transpiration and stomatal conductance, resulting in a trend toward improved water use efficiency. Additionally, D and T treatments promoted higher berry weights in the first half of the season, likely due to improved water status, while P had the opposite effect. All treatments altered berry ripening dynamics, leading to higher titratable acidity and lower must pH without reducing yield. These findings demonstrate that modifying traditional, easily mechanizable practices—such as topping—and incorporating new products like diatomaceous earth are effective strategies for mitigating summer heat stress and delaying ripening in hot, arid regions.
Funding Support: Bronco Wine Co. Chair in Viticulture
Adan Solis | Guadalupe Partida | Vincenzo Cianciola | Alessandro De Rosa | Marco Saldivar |
Xavier Rideout | William Whalen | Luca Brillante*
Physiological and Ripening Responses of Cabernet Sauvignon to Plant Growth Regulators Under Drought and Heat Stress
Adan Solis, Guadalupe Partida, Vincenzo Cianciola, Alessandro De Rosa, Marco Saldivar, Xavier Rideout, William Whalen and Luca Brillante*
*Department of Viticulture and Enology, California State University Fresno, 2360 E Barstow Ave, Fresno, CA, 93740, lucabrillante@csufresno.edu
High temperatures and water stress can significantly affect vine physiology and grape ripening, highlighting the need for effective strategies to optimize plant responses. Plant growth regulators (PGRs), including abscisic acid (ABA), ethylene, and salicylic acid, have been proposed to modulate stress responses and ripening processes in grapevines. However, their comparative effects in winegrapes remain underexplored. This study aimed to evaluate their influence on gas exchange, water stress tolerance, and grape composition in commercial settings. A field trial was conducted in a commercial Cabernet Sauvignon (Vitis vinifera L.) vineyard grafted onto 1103P rootstock in the Central Valley of California, a hot and arid climate, using a randomized complete block design with ABA, ethephon, and salicylic acid applied at veraison alongside an untreated control. Physiological responses were assessed throughout the ripening period, including leaf gas exchange, and midday stem water potential. At harvest, fruit composition—including total soluble solids (TSS), pH, and titratable acidity—was analyzed using high-performance liquid chromatography, while yield components were recorded. Salicylic acid-treated vines exhibited lower stress levels, indicated by fewer negative midday stem water potential values than the control. In contrast, ethephon-treated vines had more negative midday stem water potential values, suggesting increased water stress. In the early ripening phase, salicylic acid increased An and gs, but these parameters declined in the later stages. ABA-treated vines exhibited higher TSS at harvest, while no significant effects on yield were observed across treatments. These findings suggest that salicylic acid can enhance stress tolerance and early-season carbon assimilation, while ABA can accelerate sugar accumulation without affecting yield. The study provides insights into the potential role of PGRs in modulating vine stress responses and ripening dynamics under field conditions. Further research is needed to refine application strategies and assess their long-term effect on vineyard performance.
Funding Support: Bronco Wine Co. Chair in Viticulture
Marco Saldivar | Guadalupe Partida | Vincenzo Cianciola | Alessandro De Rosa | Adan Solis |
Xavier Rideout | William Whalen | Luca Brillante*
Effects of Calcium Carbonate and Diatomaceous Earth on Vine Physiology and Grape Composition in a Hot, Arid Climate
Marco Saldivar, Guadalupe Partida, Vincenzo Cianciola, Alessandro De Rosa, Adan Solis, Xavier Rideout, William Whalen and Luca Brillante*
*Department of Viticulture and Enology, California State University Fresno, 2360 E Barstow Ave, Fresno, CA, 93740, lucabrillante@csufresno.edu
High temperatures and water stress can significantly affect vine physiology and grape quality, highlighting the need for effective mitigation strategies. Particle films such as calcium carbonate have been explored as potential tools to improve plant resilience under challenging environmental conditions. A field trial was conducted in a commercial Cabernet Sauvignon (Vitis vinifera L.) vineyard grafted onto 1103P rootstock in the Central Valley of California, a hot and arid climate, using a randomized complete block design with calcium carbonate and diatomaceous earth applied twice—at veraison and two weeks later—alongside an untreated control. Throughout the ripening period, physiological parameters such as net assimilation, stomatal conductance, and leaf temperature were monitored. The grape composition was measured routinely during ripening, including total soluble solids (TSS), pH, titratable acidity (TA), and anthocyanin profiles, while yield components were analyzed at harvest. Calcium carbonate slightly improved net assimilation in the second half of ripening, but had no effect on stomatal conductance. The control treatment exhibited slightly higher leaf temperatures during this period. Vines treated with diatomaceous earth exhibited consistently lower stem water potential throughout the experiment, beginning from an initially lower baseline, indicating a persistent trend rather than a treatment-induced response. Yield was not affected by either treatment. Regarding grape composition, calcium carbonate-treated vines produced fruit with higher pH and lower TA, which may be undesirable, while TSS remained similar in all treatments. These findings indicate that while calcium carbonate enhanced leaf carbon assimilation, it negatively affected berry acidity and pH balance. Diatomaceous earth-treated vines exhibited persistently lower stem water potential throughout the experiment, originating from an initially lower baseline, suggesting a consistent trend without clear physiological benefits. Further research is needed to determine whether these treatments could be optimized or if alternative approaches may be more effective in vineyard management under varying climatic conditions.
Funding Support: Bronco Wine Co. Chair in Viticulture
Xavier Rideout | Guadalupe Partida | Vincenzo Cianciola | Alessandro De Rosa | Adan Solis | Marco Saldivar | William Whalen | Luca Brillante*
Natural Biopolymer-Based Coatings to Improve Water-Use Efficiency and Heat Tolerance in Cabernet Sauvignon
Xavier Rideout, Guadalupe Partida, Vincenzo Cianciola, Alessandro De Rosa, Adan Solis, Marco Saldivar, William Whalen and Luca Brillante*
*Department of Viticulture and Enology, California State University Fresno, 2360 E Barstow Ave, Fresno, CA, 93740, lucabrillante@csufresno.edu
Climate change has intensified droughts in California, posing challenges to viticulture. Elevated temperatures can reduce photosynthetic efficiency by limiting CO₂ assimilation, increasing photorespiration, and inducing physiological stress. Heat can also accelerate total soluble solids (TSS) accumulation, decrease acidity, and compromise fruit quality. To mitigate these effects, natural biopolymer-based coatings have been explored for their potential to modify plant water use and physiological responses. This study evaluates the effects of three biopolymer-based treatments: di-1-p-menthene (a terpene-based polymer from pine resin), xanthan gum (a microbial polysaccharide), and starch (a plant-derived polysaccharide) on water stress, leaf gas exchange, and vine physiology in Cabernet Sauvignon grown in the Central Valley. Treatments were applied at pre-veraison and veraison, with physiological responses assessed through gas exchange and stomatal conductance (measured using a LICOR-6800) and stem water potential (measured via pressure chamber). Fruit composition, including TSS, pH, and titratable acidity, was analyzed using high-performance liquid chromatography. Results indicated that starch application improved net assimilation after the second application without significantly altering stomatal conductance or stem water potential, demonstrating an improvement in water-use efficiency. Di-1-p-menthene application delayed ripening, leading to lower TSS accumulation while maintaining acidity, while xanthan gum accelerated TSS accumulation and slightly reduced acidity. At harvest, no significant differences were observed in yield components across treatments. These findings suggest that natural biopolymer-based coatings can influence vine water relations and fruit ripening dynamics, offering potential tools for drought adaptation. Starch may enhance carbon assimilation efficiency, while di-1-p-menthene could be leveraged to modulate ripening and acidity retention in warm climates. Further research is needed to refine application strategies, providing grapegrowers with sustainable solutions to improve resilience against climate change.
Funding Support: Bronco Wine Company Chair in Viticulture
Vincenzo Cianciola | Adan Solis | Marco Saldivar | Xavier Rideout | William Whalen | Eve Laroche-Pinel | Luca Brillante*
Deficit Irrigation Strategies for Sustainable Grapevine Production in the San Joaquin Valley: Three Years of Insights
Vincenzo Cianciola, Adan Solis, Marco Saldivar, Xavier Rideout, William Whalen, Eve Laroche-Pinel and Luca Brillante*
*Department of Viticulture and Enology, California State University Fresno, 2360 E Barstow Ave, Fresno, CA, 93740, lucabrillante@csufresno.edu
As drought conditions intensify in the San Joaquin Valley, grapegrowers face increasing pressure to optimize water use while maintaining productivity. This study evaluates the physiological responses of grapevines to different deficit irrigation strategies over three years, providing practical guidance for sustainable vineyard management. Conducted in a commercial Cabernet Sauvignon × 1103 Paulsen vineyard, this research assessed the effects of sustained deficit irrigation (SDI) and regulated deficit irrigation (RDI) strategies during the 2022 to 2024 seasons. A semi-autonomous irrigation system monitored actual water applications using flow meters. SDI treatments supplied 40, 60, 80 or 100% of crop evapotranspiration (ETc), while RDI treatments adjusted water availability pre- and postveraison (e.g., 100/40, 80/60, 60/100). Stem water potential and gas exchange were measured from June through harvest, with grape composition monitored from veraison onward. Yield components were evaluated at harvest. While vines receiving 40% ETc under SDI showed significant reductions in performance compared to the 100% ETc control, RDI strategies and SDI treatments with moderate reductions in ETc achieved similar or improved outcomes while conserving water. This study provides critical insights into the effects of deficit irrigation on vine water status, gas exchange, berry composition, and yield. The findings offer practical recommendations for growers seeking to enhance water-use efficiency without compromising grape quality, supporting the long-term sustainability of viticulture in drought-prone regions.
Funding Support: American Vineyard Foundation; California State University – Agricultural Research Institute
Tanner Dollar | Francisco Ochoa-Corona | Nathan Walker | Stephen Marek | Mustafa Jibrin*
Survey and Characterization
of Grape Black Rot in Oklahoma
Tanner Dollar, Francisco Ochoa-Corona, Nathan Walker, Stephen Marek and Mustafa Jibrin*
*Oklahoma State University, 127 Noble Research Center, Stillwater, OK, 74075, Mustafa.Jibrin@okstate.edu
Locally crafted Oklahoma grape products have been the center of focus and development as the state continues to grow its interest and production in Oklahoma-grown grapes. Grape black rot, caused by the fungus Phyllostica ampelicida, is considered one of the most economically impactful diseases affecting grapevines in Oklahoma. However, there is a paucity of information on the epidemiology, population, and fungicide sensitivity of P. ampelicida in Oklahoma. The objectives of this study were to survey and characterize the grape black rot disease in Oklahoma. A survey of vineyards in eight counties was conducted in 2024, during the dormant and active growing stages. Samples of leaves, mature berries, mummies, and canes were collected in sterile sampling bags, placed on ice, and taken to the laboratory for further processing. Pathogens were isolated from excised areas surrounding diseased lesions on collected samples. Excisions were washed with sterile tap water, placed in 1% NaClO for 1 min, and transferred to acidified potato dextrose agar (APDA). A sterile loop was used to transfer each unique fungal growth to new PDA. More than 2000 fungal isolates have been recovered thus far from different grapevine varieties. Agar plugs of each isolate were stored in 30% glycerol and kept at -80°C. DNA was extracted from mycelial growth on PDA and processed using PCR with primers targeting the ITS region. Purified PCR products were sequenced at the OSU DNA Core Facility, Stillwater, using the Sanger sequencing method. Results from BLAST search identified isolates that are P. ampelicida and other fungi. Additional sequencing based on the β-tubulin, Calmodulin, TEF1, GDPH, and ACT primers are ongoing and will be presented. Our results are important for identification of the species causing grape black rot in Oklahoma and forming a basis for additional studies on population structure, epidemiology, and fungicide screening.
Funding Support: Oklahoma Department of Agriculture, Food, and Forestry, Oklahoma Agricultural Experimental Station
Madison Shaw | Devin Rippner | Jake Schrader | Michelle Moyer*
How Grow-Tube Type Influences the Vine Microclimate in Winter
Madison Shaw, Devin Rippner, Jake Schrader and Michelle Moyer*
*Washington State University, 24106 North Bunn Rd, Prosser, WA, 99350, michelle.moyer@wsu.edu
Cold injury is an issue for grapegrowers in regions with low winter temperatures. This injury often occurs when air temperatures drop faster than the vines can acclimate. There are viticultural practices that may exacerbate this risk of damage, including the use of grow tubes overwinter. We addressed this concern through a series of experiments that observed air temperature immediately surrounding Vitis vinifera Chardonnay vines when grown in paper, plastic, or no grow tubes during the 2024 to 2025 winter in eastern Washington State. The experiment used a randomized block design, with four replicates per treatment. Internal-tube temperate (or immediately surrounding temperature in the case of no tubes) was recorded every 15 min using HOBO data loggers; solar radiation was recorded at the nearby AgWeatherNet ‘Prosser’ weather station. Overnight, all treatments achieved the same air temperature immediately surrounding the vine. During the day, the range in temperature difference between paper tubes and no tubes was 3°C. This temperature difference range exceeded 14°C comparing plastic tubes to no tubes, with the air temperature inside plastic grow tubes being warmer than ambient air. The largest differences between ambient and plastic grow tube temperatures were generally associated with sunny days. Daily accumulated solar radiation was a positive predictor for increased daytime air temperature inside plastic grow tubes (R2 = 0.58) over ambient air temperatures, but had no influence on the daytime air temperature inside paper grow tubes (R2 = 0.007). We are also investigating the effect these daytime temperature swings have on bud cold hardiness. While preliminary, this study highlights the role grow tube material choice may have on vine winter temperature response. Results could be used to enhance cold-hardiness models for young vines, accounting for grow tube material choice and forecast weather conditions.
Funding Support: Washington State University, USDA National Institute of Food and Agriculture, Hatch project 7005262, and USDA-ARS project #2072-30500-001-000-D.
Jesse Stevens | Michelle Moyer* | Maria Mireles
Integrating UV-C and Canopy Management for Grape Powdery
Mildew Control
Jesse Stevens, Michelle Moyer* and Maria Mireles
*Washington State University, 24106 North Bunn Road, Prosser, WA, 99350, michelle.moyer@wsu.edu
The germicidal effects of UV-C light (254 nm) have been used as a method of grape powdery mildew (Erysiphe necator) suppression in multiple crops, including grapevines (Vitis vinifera). The use of UV-C light in Washington vineyards may help mitigate fungicide resistance by introducing new methods to expand IPM strategies for grape diseases. However, since the application of UV-C cannot be adjusted like traditional sprays (i.e., changes in water or air volume), information is needed on how grapevine canopy management influences the effectiveness of UV-C light applications. In 2023 and 2024, we conducted a study on the effectiveness of hybrid fungicide/ UV-C regimes and canopy management techniques on powdery mildew management. The study included integrated once and twice a week UV-C applications (200 J/m2) during the powdery mildew “critical window” (start of bloom to 4 wk post full-bloom), an unsprayed control, and a sprayed grower control. Within each of these management regimes, we also nested and compared disease control between canopy management strategies, including shoot thinning, shoot thinning + early fruit zone leaf removal, and a no canopy management control. In both years, canopy management did not help nor hinder disease severity in an already effective mildew management strategy, including both UV-C regimes and the grower control (p = 0.75). Canopy management did, however, have a significant effect in reducing mildew severity in the high-disease pressure unsprayed controls (p < 0.0001). Yield and fruit quality differences were primarily due to differences in fungicide treatments, not canopy management. This information re-verifies the usefulness of UV-C light as a method of grape powdery mildew control and highlights the effectiveness of canopy management in high-disease pressure situations.
Funding Support: Washington State Grape and Wine Research Program, Washington State University Auction of Washington Wines, Washington State wine grape growers and winery through the Washington State wine commission, Northwest Center for Small Fruits Research
Gwendolyn Richards* | Cristina Lazcano | Charlotte Decock | Stewart Wilson
Assessing Carbon Saturation Potential of Regeneratively Managed Vineyard Soils
Gwendolyn Richards,* Cristina Lazcano, Charlotte Decock and Stewart Wilson
*Cal Poly San Luis Obispo, 1908 Corralitos Ave, San Luis Obispo, CA, 93401, gwendolynarichards@gmail.com
Soil carbon (C) storage is widely recognized as essential to both reducing atmospheric CO2 levels and improving soil health. Interest is rising among viticulturalists in California in adopting regenerative practices that store C. To optimize soil C storage, it is important to understand both its potential and limitations. It is well known that soil mineralogy constrains the potential of a soil for longer-term C storage. By assessing C saturation points of different soils, a vineyard’s soil C deficit can be determined and management can be catered accordingly. This study draws on soil samples from 87 vineyard soils with a long history of regenerative management to quantify the C saturation potential in California vineyards. The data set represents a wide range of soil mineralogical properties. Management practices include cover cropping, compost application, no-till, and grazing, with some practices adopted for up to 25 years. Soil organic C content across the data set ranges between 0.28 and 5.67%. To evaluate C storage potential, we plan to isolate two pools of C: particulate organic matter (POM) with a relatively fast turnover rate and mineral-associated organic matter (MAOM) associated with longer-term storage. In addition, all soil samples were analyzed for soil texture and oxalate extractable iron and aluminum. We aim to evaluate whether vineyards with a long history of regenerative management are reaching their C storage potential, and to determine the C storage deficit for participating vineyard blocks. Our findings will support new recommendations for promoting C storage in regenerative vineyards, taking into account mineralogical constraints.
Funding Support: Foundation for Food and Agriculture Research
Amanda Rodriguez* | Joshua Garcia | Axel Herrera | Alicia Hans | Kerri Steenwerth | Kabir Peay | Elisabeth Forrestel | Cristina Lazcano
Arbuscular Mycorrhizal Fungal Abundance and Diversity Across Vineyards in the Western United States
Amanda Rodriguez,* Joshua Garcia, Axel Herrera, Alicia Hans, Kerri Steenwerth, Kabir Peay, Elisabeth Forrestel and Cristina Lazcano
*University of California-Davis, 387 N Quad, Davis, CA, 95616, anrodrig@ucdavis.edu
Arbuscular mycorrhizal (AM) fungi are a well-known example of microbial symbiosis, playing a critical role in enhancing nutrient and water uptake, improving soil structure, and supporting ecosystem resilience. In winegrape production, where a balanced nutrient supply is vital to fruit quality, AM fungi facilitate soil exploration of essential nutrients and water, helping maintain optimal vine health and fruit development without promoting excessive vegetative growth. These benefits have spurred a global market for AM fungal inoculants, valued at $996 million, to enhance soil health and crop productivity. However, commercial inoculants face significant limitations, including high rates of nonviability and reliance on only a few fungal species. This contrasts with evidence suggesting that diverse native AM fungal communities often outperform commercial inoculants, underscoring the importance of understanding native AM fungal biodiversity and its interactions with grapevines under varying conditions. However, the extent to which AM fungi symbiosis is influenced by factors such as climate, soil properties, and plant genotype remains poorly understood. This study investigates AM fungal communities across 11 vineyards along an edaphoclimatic gradient from Oregon’s Willamette Valley to California’s Santa Maria Valley. AM fungal colonization was assessed through traditional microscopy and community diversity data was obtained from ITS2-targeted amplicon sequencing. These metrics of abundance and diversity were correlated with soil physical, chemical, and biological characteristics. Our study observed high colonization rates in all analyzed samples. Findings show regional soil and climatic differences shape AM fungal abundance and community composition. Our research aims to guide adaptive vineyard management strategies by providing crucial insights into the spatial dynamics of AM fungal interactions in vineyards.
Funding Support: Foundation for Food and Agriculture Research, California Department of Food and Agriculture
Marnelle Salie* | Runze Cliff Yu | Qun Sun | Keith Striegler | Sonet Van Zyl
Effect of Training System and Pruning Severity on Teroldego Grapevines in the San Joaquin Valley, California
Marnelle Salie,* Runze Cliff Yu, Qun Sun, Keith Striegler and Sonet Van Zyl
*Gallo, 600 Yosemite Blvd., Modesto, CA, 95354 & Department of Viticulture and Enology, California State University Fresno, 2360 E Barstow Ave, Fresno, CA, 93740, marnelle.salie@ejgallo.com
Proper training and pruning systems are crucial to winegrape production. These viticultural practices affect vine physiology, yield, fruit composition, and wine quality. However, for the Vitis vinifera variety Teroldego, studies have not been conducted on the appropriate training and pruning method for the San Joaquin Valley of California. Teroldego is primarily used for red blends due to its high anthocyanins and mild tannins. Traditionally, it is head-trained and cane-pruned, a very expensive way to farm winegrapes due to the rising cost of hand labor. In this trial, Teroldego was evaluated using two training/pruning systems: head-trained/cane-pruned and cordon-trained/spur-pruned from 2021 to 2023 on a quadrilateral trellis. Each training system treatment received three levels of pruning severity: five, 10, and 15 retained nodes per 0.45 kg of pruning weight to compare both methods equally through balanced pruning. Yield, vegetative growth, pruning components, fruit composition, wine quality, and economic performance were evaluated. Yield and yield component results showed significant vintage interactions, but pruning severity had the greatest influence on cluster number per vine, leading to greater yields in treatments with more retained nodes. Fruit composition differed among treatments due to crop load, but all treatments achieved target maturity and were within industry quality standards. Shoot density was greater with more retained nodes; however, no consequences were observed in the fruit or wine. For growers, switching from head-trained/cane-pruned to cordon-trained/spur-pruned systems allows more vineyard mechanization and ~76% savings on pruning costs. This trial shows an opportunity for Teroldego to be grown more economically in the San Joaquin Valley by lowering operational costs while maintaining viable yields and equivalent quality.
Funding Support: Gallo
Carlos Perez Perez | Claudia Gonzalez Viejo | Sigfredo Fuentes | Juan Ignacio Valiente Banuet*
Proximal Multispectral Imaging
and Artificial Neural Networks for Assessing Grape Ripeness and Quality
in Vineyards
Carlos Perez Perez, Claudia Gonzalez Viejo, Sigfredo Fuentes and Juan Ignacio Valiente Banuet*
*Tec de Monterrey, Epigmenio González 500, Fracc, San Pablo, Querétaro/76130, Mexico, valiente@tec.mx
The integration of multispectral proximal sensing and artificial intelligence provides a precise approach to monitor grape ripeness and quality in vineyards. Our study utilized a multispectral camera operating across six wavebands: blue (475 nm), green (560 nm), red (668 nm), red edge (717 nm), near-infrared (842 nm), and thermal (8 to 14 µm) to capture multispectral imagery that was correlated with critical grape-quality data from Cabernet, Merlot, and Parellada grape cultivars from the 2022 and 2023 vintages. The physiochemical parameters of total soluble solids (TSS), titratable acidity (TA), pH, soluble phenols, and monomeric anthocyanins were estimated using machine learning models based on artificial neural networks. Eleven models were developed, encompassing two general models for red cultivars and Parellada and nine specific models targeting individual chemometric traits. Individual models exhibited robust predictive performance, achieving correlation coefficient values above 0.80 in all models. TSS had the highest correlation coefficient of 0.96 on red cultivars, while TA had the best performance in Parellada models, with a correlation coefficient of 0.90. General models for red and white cultivars effectively predicted all parameters with correlation coefficient values of 0.91 for each one. The study confirmed the reliability of these models, demonstrating no signs of over- or underfitting. Our findings highlight the potential of artificial neural network-driven multispectral sensing to facilitate automated quality trait assessment via unmanned terrestrial vehicles, paving the way for enhanced precision viticulture practices and vineyard management.
Funding Support: Tec de Monterrey (Queretaro) Ph.D. Scholarship Secreteria de Ciencia, Humanidades, Tecnología e Inovacion (México)- Scholarship (1104865)
Samarth Rao | Brayden Hoke | Esther Ko | Karen Browning | Diana Zamora-Olivares* | Eric Anslyn
Untargeted Metabolomic Analysis of Heat Stress Response in Cabernet Sauvignon Grapevines
Samarth Rao, Brayden Hoke, Esther Ko, Karen Browning, Diana Zamora-Olivares* and Eric Anslyn
*The University of Texas at Austin, 2515 Speedway, Austin, TX, 78712, diana_z.o@utexas.edu
Worldwide, the United States is the fourth-largest wine-producing country, with 87% of grapes harvested from Vitis vinifera used for wine production. In Texas, where grape cultivation has a rich heritage and faces ever-increasing environmental challenges, understanding the physiological and metabolic responses of grapevine leaves to sustained heat stress is crucial to maintain crop quality and resilience. In this study, we investigated the effects of sustained heat stress on the secondary metabolite profiles of Cabernet Sauvignon grapevine leaves in a greenhouse with controlled temperatures (27 to 35°C). Experimental groups were subjected to heat treatment for 1, 3, 6, 10, and 13 days. Each heat-exposed group was further divided based on the timing of light exposure (morning versus evening), allowing us to assess the interplay between heat stress and light conditions. Control samples, harvested at corresponding time points without heat exposure, provided a baseline for comparison. Metabolites were extracted from leaf tissues and analyzed using high-resolution liquid chromatography–mass spectrometry for untargeted metabolomic profiling. Preliminary results revealed significant alterations in key secondary metabolites, suggesting that prolonged heat exposure triggers distinct metabolic reprogramming in grapevine leaves. Multivariate statistical analyses, including principal component analysis and partial least squares discriminant analysis, were employed to delineate correlations and identify potential biomarkers associated with heat-induced stress responses. This research represents one of the first efforts to discern the effects of heat stress on the secondary metabolite profiles of Texas grapevines. The findings not only enhance our understanding of stress physiology in grapevines but also pave the way for developing targeted strategies to improve crop resilience in a warming climate.
Funding Support: UT Austin
Stefano Zanoni* | Alessandro Bignardi | Sara Ammanniti | Silvia Carlin | Tomas Roman | Massimo Bertamini | Michele Faralli
Kaolin and Zeolite Reduce Drought Damage to Gewürztraminer and Influence Berry Composition, Must Quality, and Wine Aroma
Stefano Zanoni,* Alessandro Bignardi, Sara Ammanniti, Silvia Carlin, Tomas Roman, Massimo Bertamini and Michele Faralli
*University of Trento (C3A, Centro Agricoltura Alimenti Ambiente), Via Mach 1, San Michele all’Adige, 38098, Italy, stefano.zanoni@unitn.it
Climate change is affecting Mediterranean viticulture regions due to frequent abiotic stress conditions such as drought and heat stress, which threaten grape and wine quality. Rock powders (Kaolin, Zeolite) have been identified as a possible adaptation strategy for abiotic and biotic stresses in grapevine. They influence leaf physiology and modify berry quality, thus wine characteristics, mainly by increasing organ reflectivity. This project assessed these rock powders’ influence on grapevine physiology (leaf gas-exchange, VPDleaf); berry sunburn incidence; and berry composition, must quality, and wine aroma. We investigated 3% kaolin and 3% zeolite in a 2-yr trial (2023 to 2024) on Gewürztraminer, an aromatic cultivar in northern Italy (Trentino Alto Adige), in an east-west oriented vineyard trained to a vertical shoot-positioned trellis system and Guyot pruned (two spurs, one fruiting cane, nine buds). Rock powders were applied to both canopy sides every 14 days and after rainfall in a randomized Latin-square design (252 vines, 3 rows, 12 plots each, n = 36), with bunch-zone leaf removal (No LR, LR BBCH75, LR BBCH81). Five and six applications were carried out in 2023 and 2024, respectively. Both kaolin and zeolite reduced leaf and berry temperature (p < 0.001, -6°C and -4°C, respectively), significantly limiting sunburn in berries (p < 0.05). Leaf physiology showed few differences between treatments, likely due to vintage-specific conditions, confirming that in rainy years, rock powders do not hinder ripening or physiological fitness, while preserving quality in hot/dry years. Some significant differences in aromatic compounds were found in musts and wine, however, wine tasting revealed no perceptible differences. Future studies will focus on the terpene biosynthesis pathway (MEP, MEV) under drought and heat stress to better clarify kaolin and zeolite effects on must and wine aroma.
Funding Support: University of Trento, Lithos Crop Protect GmbH
Shijian Zhuang* | Karl Lund | Matthew Fidelibus | Philippe Rolshausen
Evaluation of Seven Rootstocks Under Drought and Saline Condition for Wine Varieties in the Southern San Joaquin Valley
Shijian Zhuang,* Karl Lund, Matthew Fidelibus and Philippe Rolshausen
*University of California Cooperative Extension at Fresno County, Suite 210-B, 550 E Shaw Ave, Fresno, CA, 93710, gzhuang@ucanr.edu
Soil salinity and saline groundwater are primary challenges for viticulture in the western San Joaquin Valley, which accounts for 60% of winegrape production in California. Great uncertainty regarding availability of surface water and continuing drought have jeopardized sustainable grape production in this region. Unpredictable winter precipitation and limited outsourced water for leaching have made the saline condition more severe. Boron is the main concern of toxicity for this region. A three-way (two varietals × two irrigation regimes × seven rootstocks) split-block field trial was established in 2020 at the UC Westside Research and Extension Center near Five Points. Two varietals (Barbera and Colombard) and seven rootstocks (1103P, 140 Ruggeri, Ramsey, GRN3, Freedom, RS3, and own root) were replicated four times with seven vines designated as an experimental unit. Two irrigation regimes were used: 40% ETc and 80% ETc from budbreak to harvest. Freedom had the most accumulated yield and the largest canopy size, measured by pruning weight, and less B in the plant tissues. Rootstocks mainly affected berry pH and titratable acidity, while berry total soluble solids were affected more by yield. Water deficit caused yield reduction by reducing berry weight, while also reducing pruning weight. No interaction of rootstock and irrigation regimes was found. The two-year results highlighted the challenges of growing grape in such saline conditions and the importance of selecting the optimum rootstock for better vine growth and crop production.
Funding Support: CA Grape Rootstock Commission
