Dissertation
Varietal differences in water relations of wine grapes
Doctor of Philosophy (PhD), Washington State University
01/2019
Handle:
https://hdl.handle.net/2376/16813
Abstract
Wine grape varieties are classified by their water stress response in two groups: Isohydric varieties showing high and constant water status under drought due to highly sensitive stomata and anisohydric varieties showing low and variable water status under drought due to insensitive stomata. We investigated the soundness of this classification for 18 different varieties in eastern Washington. From 2015 to 2018, dry-down cycles were applied to the vineyard until severe signs of stress were apparent. Physiological parameters as well as soil moisture (ϴv) were monitored. Our results show that there was a continuum of midday leaf water potential pattern (Ψl), progressing from a linear drop to one that shows a plateau down to a level of ϴv. There was also a continuum in the minimal midday Ψl recorded (from -1.3 to -1.9 MPa). Stomatal sensitivity was not correlated with the minimal midday Ψl. When an internal regulation model of Ψl was applied, most varieties showed an efficiency of the stomata in controlling against water potential drop. Chardonnay, however, showed a potential riskier strategy in terms of hydraulic failure. The model’s parameter σ was not correlated with the minimal midday Ψl, nor was it correlated with stomatal sensitivity. In a second experiment, we used a design of scion/rootstock combinations to isolate the effect of the root material, canopy material and grafting union on the water status and stomatal responses seen at the leaf level. Two model genotypes Grenache and Syrah were monitored in 2017 and 2018 in self-grafted, reciprocally grafted and own-rooted combinations while the soil is drying after standardizing the leaf area. No rootstock, scion or grafting union effect was found in any of the combinations. We conclude that leaf area might be an important confounding factor in determining water stress responses among genotypes and that leaf water stress response is not an inherent genetic characteristic. In a third experiment, we tested the effect of vapor pressure deficit (VPD) on stomatal response in a growth chamber setup under high ϴv. When VPD increased from 1.5 to 2.8 KPa, gs decreased by a 1.5 and midday Ψl decreased by a 1.14-fold
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Details
- Title
- Varietal differences in water relations of wine grapes
- Creators
- Joelle Martinez
- Contributors
- Markus Keller (Advisor)Markus Keller (Committee Member)Michelle Moyer (Committee Member)Lee Kalcsits (Committee Member)Bhaskar Bondada (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Horticulture
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 220
- Identifiers
- 99900581502701842
- Language
- English
- Resource Type
- Dissertation