Browsing by Author "Centinari, Michela"
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- Identifying an Early Leaf Removal Threshold for Grüner Veltliner, a High-Yielding, High-Vigor CultivarHarner, Andrew D.; Smith, Maria S.; Keller, Stephanie T.; Hopfer, Helene; Centinari, Michela (American Society for Enology and Viticulture, 2024-03-11)Background and goals: Early leaf removal (ELR) is a canopy management practice that can reduce bunch rot and improve fruit maturity by modifying cluster architecture and fruit zone microclimate. The goal of this study was to identify an ELR threshold that balances improvements to fruit quality and reductions in yield for a highly vegetative and high-yielding Vitis vinifera cultivar grown in the eastern United States, Grüner Veltliner. Methods and key findings: Over two consecutive years, we applied a wide range of ELR severities (three to 12 leaves per shoot) at trace bloom (Eichhorn-Lorenz [E-L] stage 19) and evaluated relationships between increasing ELR severity and fruit set, yield param-eters, fruit maturity, bunch rot, and juice volatile composition at harvest. In the first year, increasing ELR gradually reduced fruit set, subsequently lowering yield via reducing berry number and cluster weights. Additionally, ELR increased fruit ripeness while reducing rot incidence. However, extreme ELR (10 to 12 leaves per shoot) negatively affected inflorescence floret number and fruitfulness in the following year. In the second year, only high ELR severities (eight to 12 leaves per shoot) reduced yield parameters, and improvements in fruit ripeness or bunch rot were not observed, likely because of poor weather conditions during fruit ripening. The impact of increasing ELR severities on juice volatile composition was largely limited to benzaldehyde (a volatile phenylpropanoid), which was negatively affected by ELR in both years. Conclusions and significance: Removal of six to eight leaves per shoot appeared to be the optimal ELR severities for grapegrowers seeking crop management and rot reduction for high-yielding cultivars like Grüner Veltliner. However, as reported in the second year of this study, the effects of ELR may vary by year and be limited by unfavorable weather conditions.
- Influence of Region on Sensory and Chemical Profiles of Pennsylvania Gruner Veltliner WinesKeller, Stephanie T.; Harner, Andrew D.; Centinari, Michela; Elias, Ryan J.; Hopfer, Helene (MDPI, 2021-04-10)The influence of cultural and environmental factors on the sensory and chemical profiles of wines has been the subject of research investigation for many years, and an examination of these relationships can help determine whether wine regional trends exist. The present study investigated the chemical and sensory factors that drive regional differences in Pennsylvania Grüner Veltliner wines through a controlled winemaking study across two vintages in 2018 and 2019. Descriptive analysis was used to identify key sensory attributes of Pennsylvania Grüner Veltliner. Intensities of these attributes were evaluated in wines vinified under identical conditions from grapes harvested across nine Pennsylvania vineyards. Chemical profiles of finished wines were examined through volatile, phenolic, and color analyses. Significant sensory differences were found between wine regions, with some trends consistent across both vintages; however, regionality based on compositional analyses was less clear. As the first study to examine Pennsylvania Grüner Veltliner wines sensorially, results revealed sensory characteristics that can be useful for wineries and their tasting room staff in marketing these lesser-known white wines to wine consumers as the variety grows in popularity in the state.
- Modeling the Impacts of Weather and Cultural Factors on Rotundone Concentration in Cool-Climate Noiret Wine GrapesHarner, Andrew D.; Vanden Heuvel, Justine E.; Marini, Richard P.; Elias, Ryan J.; Centinari, Michela (Frontiers, 2019-10-15)The sesquiterpenoid rotundone is the compound responsible for the "black pepper" aroma of many plant species, including several economically important wine grape varieties. Since its identification in wine in 2008, there has been an increased interest in understanding how individual climatic or cultural factors affect the accumulation of rotundone in grapes and subsequently the level of wine "pepperiness." However, no study has assessed climatic and viticultural factors together to identify which variables have the strongest influence on rotundone accumulation. Our study aimed to fill this knowledge gap by developing a predictive model that identified factors that explain rotundone concentrations in Noiret (Vitis sp.) grapes at harvest. Over the 2016 and 2017 seasons, we measured 21 viticultural, meso- and microclimatic variables and concentrations of rotundone in Noiret wine grapes at seven vineyards in the northeastern U.S. Vineyard growing degree days (GDD v ) and the amount of solar radiation (cumulative solar exposure; CSEv) accumulated from the beginning of fruit ripening to harvest were the variables best correlated (r = 0.70 and r = 0.74, respectively) with rotundone concentrations. Linear correlations between microclimatic parameters and rotundone concentrations were weaker, but overall rotundone was negatively correlated with low (<15°C) and high (>30°C) berry temperatures. Using the 2-year data set we were able to develop a four-variable model which explained more than 80% of the variation in rotundone concentration at harvest. The model included weather [growing degree days during fruit ripening (GDD v )] and plant-related variables (concentrations of phosphorus and calcium in the leaf petiole, and crop load). The model we developed could be used by wine producers to identify sites or cultural practices that favor rotundone accumulation in Noiret grapes after performing a model validation with an additional, external data set. More broadly, the statistical approach used here could be applied to other studies that also seek to assess the effects of multiple factors on a variable of interest under varying environmental conditions.
- Prolonged phloem feeding by the spotted lanternfly, an invasive planthopper, alters resource allocation and inhibits gas exchange in grapevinesHarner, Andrew D.; Leach, Heather L.; Briggs, Lauren; Centinari, Michela (Wiley, 2022-10-05)Spotted lanternfly (Lycorma delicatula White; SLF) is a phloem-feeding planthopper invasive to the Eastern United States that can feed on a range of wild and cultivated plant species. Since its 2014 introduction in the United States, large infestations and subsequent economic damage have been reported in cultivated grapevines, but no studies have detailed grapevine physiological responses to SLF phloem feeding. This study investigated grapevine-SLF interactions, detailing how different infestation densities affect leaf gas exchange and end-season concentrations of nonstructural carbohydrates and nitrogen in vegetative and perennial tissues of two Vitis species. Effects on fruit ripeness parameters and dormant bud freeze tolerance were examined, in addition to other year-after effects. Phloem feeding by low densities (≤4 SLF shoot−1) had minimal effects, whereas greater densities (5–15 SLF shoot−1) increasingly affected carbohydrate and nitrogen dynamics in both Vitis species. Phloem feeding substantially affected starch and, to a lesser extent, total nitrogen concentrations of woody roots. Prolonged exposure strongly reduced leaf gas exchange. We conclude that intensive late-season phloem feeding by large adult SLF population densities (≥8 SLF shoot−1) can induce carbon limitation, with the potential for negative year-after effects in cases of severe belowground carbon depletion. This work presents novel insights into SLF-grapevine interactions, identifies avenues of future SLF-plant research, and assists the development of action thresholds for SLF management in vineyards.