Progress 01/02/23 to 01/01/24
Outputs
Target Audience:Grapes represent the most economically valuable fruit crop in the United States, with the total production value having more than tripled over the past decade. Michigan plays a significant role in this success, consistently ranking among the top five states for grape production, with approximately 15,000 acres dedicated to vineyards. The grape and wine industry in Michigan is one of the fastest-growing segments of the state's agricultural economy. Michigan ranks fifth nationally in vineyard acreage and is a leading producer of juice grapes. The state is also home to more than 200 wineries, a number that continues to grow each year. The sector supports around 5,000 full-time equivalent jobs and attracts over 800,000 wine-related tourists annually. Altogether, the grape and wine industry contributes an estimated $800 million in annual economic activity within Michigan. Despite this growth, grape and wine production in Michigan faces significant challenges, particularly due to climatic variability. Fluctuations in seasonal weather can impact fruit ripening, often making it difficult for growers to achieve full maturity and consistent fruit quality. This variability poses a unique challenge in cool-climate viticulture, where grapevines frequently struggle to meet their physiological requirements within the limits of a short growing season. Achieving optimal fruit maturity and high-quality outcomes under these conditions requires precise vineyard management, particularly in response to year-to-year climate shifts. This has led to increased interest in canopy management practices that can influence the microclimate surrounding grape clusters. While growers cannot control broader macroclimatic conditions or even site-specific mesoclimates, they can significantly affect the microenvironment of the fruit zone through timely and targeted viticultural interventions. Among these practices, early leaf removal has shown great promise, especially in cool-climate regions like Michigan. The 2021 canopy management research project, funded through NIFA and discussed in multiple public forums, demonstrated that early leaf removal can improve cluster microclimate, enhance sun exposure, and influence the biosynthesis of key phenolic compounds that determine grape and wine quality. Grape quality, particularly in red varieties, is heavily influenced by the accumulation of specialized metabolites such as anthocyanins, flavonols, and hydroxycinnamic acids. These compounds not only impact color but also contribute to mouthfeel and the overall sensory profile of wine. Enhancing anthocyanin content--both in quantity and profile--is especially important for winemaking success in cooler climates. Higher anthocyanin levels, along with other color-stabilizing phenolics, help promote the formation of more stable pigment structures, such as pyranoanthocyanins, which in turn improve wine color retention over time. In 2020, our research efforts focused on evaluating how changes in vineyard microclimate, particularly through crop load management and canopy modification, influence the synthesis of these phenolics during berry development. One objective was to assess the effects of both the timing and intensity of crop thinning on the vine's source-sink balance, and how this relationship affects vine vigor, fruit set, and overall fruit composition. These findings are expected to provide growers with clearer benchmarks for managing crop loads in a way that promotes both vine balance and fruit quality. Many commercial vineyard practices manipulate yields based on volume targets, but often without integrating vine vigor or balance considerations into decision-making. To encourage more informed yield management, our work has focused on developing practical metrics and tools that growers can use to align crop thinning decisions with vine physiological capacity and environmental conditions. Throughout 2020 and beyond, our team actively pursued funding opportunities to support this research, acting as principal investigators or collaborators in proposals submitted to various agencies. These include Michigan State University's Project GREEEN, the Michigan Craft Beverage Council, USDA's Specialty Crop Research Initiative (SCRI), the Michigan Department of Agriculture and Rural Development's Specialty Crop Block Grant Program, and the AFRI programs under USDA focused on plant development, climate resilience, and abiotic stress response. The research team includes key collaborators from the Departments of Entomology, Horticulture, and Earth and Environmental Sciences, reflecting a multidisciplinary approach to tackling the complex challenges facing Michigan's viticulture industry. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Students and early-career researchers were actively engaged in training activities throughout the project. Participants in the Viticulture Certificate Program--a two-year program offered through the Michigan State University (MSU) Institute of Agricultural Technology (IAT)--had the opportunity to visit the experimental vineyard at the Northwest Michigan Horticultural Research Center. These visits provided valuable exposure to vineyard design, research objectives, and site-specific viticultural practices, although hands-on activities such as pruning and canopy management were not conducted during this phase. In addition, students enrolled in HRT 336 (Viticulture and Berry Production), an undergraduate course in the Department of Horticulture, participated in guided virtual tours of vineyard plots located at both the Northwest and Southwest Michigan Research and Extension Centers. These tours provided an overview of regional growing conditions, research plots, and management strategies, supplementing classroom instruction with real-world examples. The project also supported the advanced training ofgraduate studentsandpostdoctoral researchers, who were deeply involved in all aspects of experimental work. These trainees gained experience in experimental design, field data collection, canopy management techniques, and laboratory analysis of grape composition. Their contributions were integral to the success of the project, and their involvement helped build a new generation of professionals equipped to lead in viticulture research and industry applications. How have the results been disseminated to communities of interest?Throughout 2023and 2024, the viticulture team actively collaborated with stakeholders, as well as local and regional industry organizations, to share project outcomes and maintain strong engagement across the grape and wine sector. A series of Zoom-based extension meetings were held to present project updates and foster dialogue with growers and industry professionals. These virtual sessions were supplemented by web-based extension materials, including short technical reports, recorded presentations, and video demonstrations, all focused on the performance of alternative grape varieties and their potential to mitigate production challenges. Research findings were also presented during major annual extension events, such as theGreat Lakes Fruit, Vegetable and Farm Market EXPO, theViticulture Day, and theSouthwest Michigan Horticultural Days, which was conducted online. Additional in-season meetings provided further opportunities to share results directly with growers and extension personnel. To broaden the reach of these efforts, information was disseminated through multiple communication channels, including theMichigan Grape and Wine Newsletter, MSU Extension publications, and theMSU viticulture website(www.grapes.msu.edu). Looking ahead, project results are also being prepared for presentation at scientific conferences, informal academic meetings, and as contributions to peer-reviewed scientific journals. What do you plan to do during the next reporting period to accomplish the goals?During the next reporting period, our efforts will focus on advancing both the research and outreach components of the project to further achieve its objectives. We plan to continue and expand our vineyard trials, specifically targeting canopy management strategies such as early leaf removal, shoot positioning, and crop thinning. These practices will be tested across multiple sites and cultivars to assess their effects on fruit composition, phenolic development, and overall vine balance under varying environmental conditions. Data collection will continue throughout the growing season, with emphasis on measuring vine physiology, yield components, and microclimate parameters. In parallel, laboratory analysis will focus on detailed metabolite profiling and gene expression studies to better understand the biological mechanisms influenced by these management strategies. Graduate students and postdoctoral researchers will remain actively involved in every stage of the work, from field data collection to laboratory analysis and interpretation. Their training will emphasize experimental design, data analysis, and the communication of scientific results. These efforts are essential to building research capacity and preparing the next generation of viticulture professionals. We also plan to strengthen stakeholder engagement by organizing field days, participating in regional extension meetings, and continuing our communication with growers and industry partners. In addition to in-person activities, we will produce a range of outreach materials, including technical articles, online updates, and educational resources tailored for grower use. Finally, we will begin developing decision-support tools based on the research findings to help growers better assess vine balance and guide their crop load management strategies according to seasonal conditions. Manuscripts summarizing research outcomes will also be prepared for submission to peer-reviewed journals, and results will be shared at scientific conferences and professional meetings. These combined activities will support continued progress toward the project's goal of improving grape quality and production consistency through science-based vineyard management in the face of climate variability.
Impacts
What was accomplished under these goals?
This multi-year project was designed to supportwine grape producers by evaluating and recommending vineyard management strategies that can accelerate fruit development and improve ripening outcomes in climates characterized by high variability. The ultimate aim is to achieve more consistent and higher-quality grape production across a range of growing conditions. In the 2023-24research season, experimental efforts were directed toward identifying sustainable yield levels that can reliably reach maturity under differing seasonal climates and canopy management regimes. A core aspect of this work was to ensure that yield reductions--where applied--would not compromise the vine's ability to recover and produce a full crop in the following season. One major focus was on wine grapes, where fruit quality is closely tied to the accumulation of specific phenolic compounds. These include flavonols, anthocyanins, and hydroxycinnamic acids, which contribute significantly to red wine color, texture, and aging potential. While grape genotype plays a foundational role in determining the potential for these compounds, their expression is strongly influenced by how the vineyard environment is managed. Growers cannot alter macroclimatic conditions such as regional weather patterns or site mesoclimate; however, they can meaningfully influence themicroclimatearound the grape cluster through carefully timed and targeted vineyard practices. Among these,leaf removalhas proven to be especially effective in cool-climate regions like Michigan. When applied at the right stages of berry development, leaf removal can enhance sunlight exposure and air flow around the fruit zone, leading to improved ripening and more favorable chemical composition in the berries. The 2023-24research focused on multiple wine grape varieties and evaluated how microclimate manipulation--particularly through canopy management--impacted the accumulation of phenolic compounds during the maturation process. Early results indicate that these practices can lead to improvements in the concentration and balance of color- and flavor-related metabolites, thus setting the stage for higher wine quality. Another key outcome of the 2023-24research was progress toward identifying clear indicators for crop thinning interventions. These decision points are crucial for achieving vine balance--ensuring the canopy can support the fruit load without overtaxing the vine. Historically, many yield adjustments in the industry have been made without sufficient consideration of vine vigor. The findings from this project offer a more integrated approach, helping growers align yield management decisions with the physiological capacity of the vine, ultimately supporting both current fruit quality and long-term vineyard productivity. Through this work, the project contributes valuable tools and knowledge to help growers make informed, climate-resilient management choices, enhancing both yield reliability and grape quality across diverse growing conditions.
Publications
- Type:
Peer Reviewed Journal Articles
Status:
Published
Year Published:
2023
Citation:
Influence of Early Leaf Removal on Flavonoid Accumulation and Antioxidant Capacity in Merlot (Vitis vinifera L.) Berry Components
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Progress 01/02/22 to 01/01/23
Outputs
Target Audience:The grape industry in the U.S. holds significant economic value, having more than tripled in production value over the past decade. Michigan stands out as a key contributor, ranking in the top five states nationally with 15,000 acres devoted to grape cultivation. Michigan's grape and wine sector is a rapidly growing component of the state's agricultural industry, characterized by numerous indicators: Michigan ranks fifth in the U.S. for grape acreage, boasting 15,000 acres and serving as a major producer of juice grapes. The state is home to over 200 wineries, with continual emergence of new ones annually. These wineries support a workforce of 5,000 full-time equivalents and attract over 800,000 wine-related tourists annually, contributing over $800 million to the state's economy. However, Michigan's climate presents challenges for grape and wine producers, particularly variable ripening conditions that impact yield and fruit quality at harvest. This climatic variability often leads to incomplete fruit maturation, posing limitations on quality product achievement. Addressing these challenges is essential for ensuring optimal fruit maturity and quality amidst seasonal climate variations. The wine grape industry in Michigan has seen presentations on the results of the 2022-23 early leaf removal NIFA canopy management project, offering insights into potential future developments. Key compounds in grapes, crucial for quality, are not solely influenced by genotype but can also be significantly impacted by manipulation of grapevine environmental conditions. While winegrowers cannot control macroclimate or site conditions, they can enhance microclimate conditions within the cluster area through careful selection and timing of viticultural techniques. Leaf removal, for instance, is known to effectively manipulate canopy microclimate, especially in cooler climates, resulting in significant grape quality improvements. In 2022-23, research efforts focused on vineyard microclimate modifications and their effects on the development of phenolics during grape maturation. One aim was to assess the timing and intensity of crop thinning, evaluating their impacts on vine growth, fruit set, and composition to enhance vine balance and fruit quality. To address imbalances resulting from yield manipulation, it is crucial for growers to consider vine balance in their yield management decisions. Metrics derived from research and extension delivery information can aid in decision-making processes. Seeking to support these research endeavors, funding opportunities were pursued in 2022-23, targeting programs such as MSU's Project GREEEN, the Michigan Craft Beverage Council, USDA Special Research Grants (SCRI), Michigan Department of Agriculture Specialty Crop Block Grants, and AFRI Agriculture and Natural Resources Science initiatives. Collaborative proposals involving key colleagues from various departments were developed, including Entomology, Horticulture, and Geological Science, to enhance research outcomes and impact. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?In 2022-23, students enrolled in the viticulture certificate program at Michigan State University's (MSU) Institute of Agricultural Technology (IAT) had a valuable experiential learning opportunity. As part of their two-year program, they visited the NW station experimental vineyard, gaining firsthand exposure to vineyard management practices. However, it's important to note that during this visit, students did not engage in pruning or canopy management activities. Separately, students enrolled in the Department of Horticulture's HRT336 class, focused on Viticulture and Berry Production, also benefited from a unique learning experience. They participated in a virtual tour of two plots located in the NW and SW regions. This virtual tour provided students with insights into vineyard management techniques and allowed them to observe the practical application of concepts learned in the classroom. Both experiences, though different in nature, contributed to the students' understanding of viticulture practices and enhanced their knowledge of grape production. These immersive learning opportunities align with MSU's commitment to providing hands-on education in agriculture and horticulture. How have the results been disseminated to communities of interest?Throughout 2022 and 2023, the viticulture team engaged in extensive collaboration with stakeholders, local and regional industry organizations, and utilized various online platforms, including Zoom-based extension meetings. These efforts were aimed at providing comprehensive project reports and facilitating the dissemination of valuable information to foster continued stakeholder engagement. The team produced and distributed a range of web-based extension materials focusing on the performance of several alternative grape varieties, which served to mitigate various viticultural challenges. These materials included concise reports, extension presentations, and on-site vineyard demonstrations, all geared towards providing practical insights and solutions for growers. Furthermore, the team actively shared their findings with growers and extension personnel at key annual events, such as the 2022 Great Lakes Expo, 2022 Viticulture Day, and the 2022 Southwest Horticultural Days, among others. Additionally, information was disseminated through channels such as the Michigan Grape and Wine Newsletter and relevant crop-related websites, such as www.grapes.msu.edu. In addition to these outreach efforts, the team also plans to present their research findings at scientific conferences, informal scientific meetings, and intends to publish their work as a scientific paper in a reputable journal. These multifaceted dissemination strategies underscore the team's commitment to sharing valuable insights and contributing to advancements in the field of viticulture. What do you plan to do during the next reporting period to accomplish the goals?The experiment will be conducted at Brys Estate Winery in Traverse City, focusing on Merlot, Pinot Noir, and Cabernet Franc vines (Vitis vinifera L.). Early leaf removal (ELR) techniques, both manual (ELR-MA) and mechanical (ELR-ME), will be applied at two key stages: (a) pre-bloom and (b) full bloom. A visual representation of the percentage of leaf area removed at the time of treatment, along with images of fruit-zones from control and treated vines at fruit set, will be documented. Mean values of the two cultivars across the two locations will be analyzed.Throughout the growing season, measurements will be taken to assess photosynthetic carbon assimilation, stomatal conductance, intercellular CO2 concentration, and leaf transpiration using a Licor-6400XT instrument. Additionally, fluorescence (qL, qP, ΦII, LEF, NPQ) and absorbance (vH+, gH+, ECSt) parameters will be measured using a MultispeQ instrument, aiming to observe changes in photosystem I (PSI) efficiency and canopy photosynthesis in response to ELR treatments.At harvest, vine yield and the number of clusters per vine will be determined. Individual clusters will be picked, weighed, and the number of berries per cluster counted.Subsequently, a sub-sample of 20 berries per cluster will be subjected to basic fruit chemistry analyses, including Brix, TA, and pH measurements.Currently, polyphenols are being extracted in Dr. Medina's laboratory (Food Science) through fractionation with solid-phase extraction (SPE). Over the next few months, metabolites will be profiled using a Waters Acquity UHPLC interfaced to a Waters Xevo G2-XS Q-Tof mass spectrometer. Flavonoid metabolites will be further analyzed at the Metabolomics Core at Michigan State University to understand the fruit flavonoid metabolome profile throughout ripening and at harvest in relation to ELR treatments.Furthermore, hormones involved in stress mediation (e.g., ABA, jasmonic acid, salicylic acid) are currently being measured in fruit and leaves. Data from these measurements will provide insights into the relationship between biotic stress response and secondary metabolism in response to leaf removal treatments. Preliminary data from this project have already been shared with the industry during various summer field extension activities, winter meetings, and national conferences. The project aims to continue disseminating findings to stakeholders through future outreach efforts.
Impacts
What was accomplished under these goals?
The overarching objective of this multi-year project is to evaluate and recommend vineyard management strategies that accelerate fruit development and maturation. The aim is to enhance and ensure consistent high-quality grape production in a climate characterized by significant variability. Specific objectives will be outlined in subsequent sections. In 2022-23, research efforts were directed towards determining canopy managment strategies that could be achieved across different growing season variations. For wine grapes, the quality of berries is influenced not only by genetics but also by vineyard management techniques. While winegrowers cannot control macroclimate or mesoclimate conditions, they can adopt practices to enhance microclimate conditions within the cluster area. By carefully selecting and timing relevant techniques at different stages of grape development, they can positively impact grape quality at harvest. Leaf removal, for instance, is a viticultural practice known to enhance canopy microclimate, particularly crucial in cooler climates, resulting in significant improvements in grape quality. Improvements in vineyard management practices aimed at enhancing grape composition are expected to be reflected in the resulting wines. Compounds such as flavonols, anthocyanins, and hydroxycinnamic acids are crucial for developing red wine color and mouthfeel characteristics, which are of particular importance. In 2022-23, our research on various wine grape varieties was designed to investigate the influence of vineyard microclimate modifications on the development of related phenolics during grape maturation. These findings will assist growers in identifying critical milestones for crop thinning activities aimed at optimizing vine balance and fruit quality. Industry practices often focus on manipulating yields without adequately considering vine vigor. It is important for growers to strike a balance between yield management and vine vigor to ensure overall vine health and quality grape production.
Publications
- Type:
Journal Articles
Status:
Accepted
Year Published:
2022
Citation:
VanderWeide, J.; Del Zozzo, F.; Nasrollahiazar, E.; Kennedy, J.A.; Peterlunger, E.; Rustioni, L.; Sabbatini, P. Influence of freezing and heating conditions on grape seed flavan-3-ol extractability, oxidation, and galloylation pattern. Sci. Rep. 2022, 12, 3838.
- Type:
Journal Articles
Status:
Accepted
Year Published:
2022
Citation:
VanderWeide, J.; Falchi, R.; Calderan, A.; Peterlunger, E.; Vrhovsek, U.; Sivilotti, P.; Sabbatini, P. Juxtaposition of the source-to-sink ratio and fruit exposure to solar radiation on cv. Merlot (Vitis vinifera L.) berry phenolics in a cool versus warm growing region. J. Agric. Food Chem. 2022, 70, 1042910442.
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Progress 01/02/21 to 01/01/22
Outputs
Target Audience:Grape in U.S. is the most valuable crop and total production has more than tripled in value in ten years and Michigan has been a significant contributor ranking in the top five nationally with 15,000 acres planted to grapes. The grape and wine industry in Michigan is a fast growing sector of the Michigan agricultural sector. Important numbers are: (1) Michigan ranks 5 in the USA in grape acreage (15,000 acres) and it is a major producer of juice grapes in USA; (2) there are more than 200 wineries with more emerging each year; (3) 5,000 fulltime equivalent are employed; 4) over 800,000 wine-related tourist visits every year; and (5) an estimated annual economic impact of the state's grape and wine industry of more than $800 million in spending. However, Michigan's climate presents several challenges to grape and wine producers, including variable ripening conditions that affect yield and fruit quality at harvest. The wine grape industry in Michigan finds a limitation to the effort of achieving quality products in a challenging environment for the physiological requirements of grapevines, too often leading to an incomplete maturation of the fruit. Under these conditions it is pivotal to achieve optimal fruit maturity every year to and quality in relation to the seasonal climate variations. Several presentations about the results of the 2021 early leaf removal NIFA canopy management project and the potential future development were made during online and face to face meetings. The profiles of the main technologically important quality compounds in grapes are not only genotype dependent but can also be significantly affected by manipulation of grapevine environmental conditions. Although winegrowers obviously cannot influence the vintage/region macroclimate or site/vineyard mesoclimate conditions, it is in their power to significantly improve microclimate conditions within the cluster area by carefully selecting relevant viticultural techniques and, moreover, by choosing the timing for their implementation at different grape developmental stages. Leaf removal is known to be viticultural practices enabling successful canopy microclimate manipulation in cool climates, leading to important grape quality improvements. The initial quantitative and qualitative input of flavonols, anthocyanins, and hydroxycinnamic acids is most relevant for the development of red wine color-mouthfeel characteristics. Thus, any improvement in anthocyanin quantitative and/or qualitative profiles may be of considerable importance for the success in cool-climate regions. Better anthocyanin yield, combined with improvements in other color-related phenolics in young wines, can offer greater potential for further formation of complex and more stable pigments such as pyranoanthocynanins and other related pigments, thus improving wine color stability over time. In 2020 our research on several wine grape varieties has been designed to reveal the influence of vineyard microclimate modification efforts on the development of related phenolics during grape maturation. One goal of our 2020 research was to relate: a) timing and b) intensity of crop thinning to impacts upon the source-sink relationship and the resulting affect upon vine growth, fruit set, and fruit composition. These results will help growers more clearly identify critical milestones for crop thinning activity aimed at enhancing vine balance and fruit quality. Industry practices often manipulate yields without considering vine vigor in the balance equation. For growers to consider vine balance in their yield management decisions, research and extension delivery information were needed to develop metrics to help with decision-making. In 2020 and 2020, funding opportunities were pursued, as PI or cooperator, to programs such as MSU's Project GREEEN, and the, Michigan Craft Beverage Council, USDA Special Research Grants (SCRI), Michigan Department of Agriculture Specialty Crop Block Grants, the AFRI Agriculture and Natural Resources Science for Climate Variability and Change and AFRI Growth and Development, Composition and Stress Tolerance "Reduce loss of plant productivity through understanding the mechanisms of plant response to abiotic stresses". Proposals include key colleagues in Entomology, Horticulture and Geological science Departments. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?The pandemic reduced immensely the opportunity for training students and professionals. Student in the viticulture certificate program, a two-year program at the Michigan State University (MSU) Institute of Agricultural Technology (IAT) during 2021had the opportunity to visit the NW station experimental vineyard but no pruning or canopy management were performed by the students. Students in the Department of Horticulture enrolled in HRT336 class (Viticulture and Berry production) had the opportunity of a virtual tour of the 2 plots in the NW and SW. How have the results been disseminated to communities of interest?During 2021the viticulture team worked with stakeholders, local and regional industry organizations, and utilized several online zoom-based extension meetings to provide relevant project reports and facilitate information dissemination for continued stakeholder engagement. Web-based extension materials related to the performance of several alternative grape varieties mitigating was produced and distributed, including short reports and 2) extension presentations and on-site vineyard demonstrations. Results shared with growers and extension personnel at our annual extension meetings, such as the 2020Great Lakes Expo, 2021Viticulture Day, 2021online Southwest Horticultural Days, and other in-season meetings. Information was also distributed via Michigan Grape and Wine Newsletter and crop-related websites (e.g. www.grapes.msu.edu). Research presentations will also be made at scientific conferences, informal scientific meetings, and as a paper in a scientific journal. What do you plan to do during the next reporting period to accomplish the goals?The overall goal of this project is to test and recommend a series of vineyard management strategies that can hasten fruit development and maturation for improved and more consistent high quality grape production in a highly variable climate year to year. This project established management viticultural practices to obtain consistent optimal quality in Michigan. In a survey administered by the viticulture team at MSU in 2010, 82% of respondents indicated that they conduct crop thinning in their vineyards, but the target yields are not driven by fruit quality parameters but by contracts with the winery/winemaker that may or may not take these factors into account or are driven by other concerns. Therefore, this study defined metrics for Michigan by addressing both the practical and the physiological aspects of vine balance issues for enhanced vine productivity, fruit, and wine quality. This research will provide detailed information to the grower to make precise management decisions to optimize grape quality under Michigan conditions. The goal of this research was to provide vineyard management strategies that can hasten fruit development and maturation for improved and more consistent high-quality wine grape production in a highly variable climate. We strongly believe that this project has the potential to provide answers and significant benefits to our 420 grape growers in Michigan.
Impacts
What was accomplished under these goals?
The overall goal of this multi-year project, for both juice and wine grapes, is to test and recommend a series of vineyard management strategies that can hasten fruit development and maturation for improved and more consistent high quality grape production in a highly variable climate. Objectives that are more specific will be detailed in following section. In 2020, research experimental efforts were focused on determine yield ranges that could be matured over a variety of growing season types and vineyard canopy management practices, while maintaining the vine's capability to return with a full crop potential the next season. In wine grapes, the main technologically important quality compounds in berries are not only genotype dependent but are affected by vineyard manipulation techniques. Although winegrowers obviously cannot influence the vintage or change the region macroclimate or the vineyard mesoclimate conditions, they can adopt techniques to significantly improve microclimate conditions within the cluster area. There are several techniques, and by carefully selecting the most relevant ones and by choosing the timing for their implementation at different grape developmental stages, they can impact positively the grape quality at harvest. Leaf removal is known to be viticultural practices improving canopy microclimate, pivotal in cool climates, leading to important grape quality improvements. Any significant vineyard management-related improvements in grape composition would normally be aimed to reflect also in the wines. Flavonols, anthocyanins, and hydroxycinnamic acids are the most relevant compounds for the development of red wine color-mouthfeel characteristics, which are particularly important. In 2020 our research on several wine grape varieties has been designed to reveal the influence of vineyard microclimate modification efforts on the development of related phenolics during grape maturation. These results will help growers more clearly identify critical milestones for crop thinning activity aimed at enhancing vine balance and fruit quality. Industry practices often manipulate yields without considering vine vigor in the balance equation.
Publications
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