Thesis
Canopy and Irrigation Management Effects on Grape Acidity
Washington State University
Master of Science (MS), Washington State University
2022
DOI:
https://doi.org/10.7273/000005180
Abstract
Grapes harvested in warm climates like eastern Washington often have lower amounts of acid than grapes harvested in cooler climates. Acidity plays a central sensory role especially in white wines due to their lack of tannins. Low acid wines with high pH are also more susceptible to microbial spoilage. Climate change will heighten acidity issues by causing hotter growing season temperatures and harsher water stress. Thus, there is a need to determine which management practices will aid in the preservation of acidity. Three canopy management treatments, two irrigation strategies, and two white wine grape varieties, Riesling and Chardonnay, were tested in a field trial at the WSU Roza vineyard in 2020 and 2021. These varieties were chosen with consultation from industry members, and their differences in acidity profiles will provide an interesting comparison. Vines either had leaf removal and shading, just leaf removal, or no treatment at all (control). These canopy treatments were replicated over vines receiving full or deficit irrigation, defined as half the amount of water applied in the full irrigation treatment. We hypothesized that removing leaves on the east side of the fruit zone after fruit set will stimulate acid production. We also hypothesized that repositioning shoots to shade berries after they begin to ripen will limit the loss of acidity during ripening. Berries were sampled throughout the growing season to track the changes in acidity as well as the effects of the treatments on berry acidity. Canopy treatments caused significant changes in fruit zone temperature, but these changes did not correlate well with any changes in fruit composition. Vines in the full irrigation regime retained more acidity than water stressed vines. These changes in acidity were primarily differences in titratable acidity and malate concentrations. Irrigation treatments did not negatively impact other quality parameters such as pH, total soluble solids, or potassium concentrations.
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Details
- Title
- Canopy and Irrigation Management Effects on Grape Acidity
- Creators
- Evan Charles Fritzke
- Contributors
- Markus Keller (Advisor)Thomas S Collins (Committee Member)Lee Kalcsits (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Horticulture, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Number of pages
- 156
- Identifiers
- 99901019941201842
- Language
- English
- Resource Type
- Thesis