Open Collections

Wilson, Nikolas

University of British Columbia

Frequency of drought events is expected to increase in many important grape-growing regions, with implications on sustainability of wine grape production. There are large differences between grapevine cultivars that have implications on effects of drought on berries, including the level of isohydricity they display and berry transpiration rates, and traits that contribute to preventing losses in yield and metabolite changes during drought are important to determine. The primary goal of this study was to quantify the degree of isohydricity of four grapevine cultivars ('Cabernet Franc', 'Semillon', 'Grenache', and 'Riesling') using different methods – predawn water potential threshold of stomatal closure, slope of the linear regression between predawn and midday water potentials, and the daily difference between predawn and midday water potentials – and determine whether degree of isohydricity has a relationship with sensitivity of berries to size and metabolite changes during progressive drought. I also sought to determine whether any relationships (if present) were dependent on phenological stage (i.e. pre- and post-veraison). It was found that the daily difference between predawn and midday water potentials has a relationship with sensitivity of changes in berry size and metabolites as predawn water potential declined. Secondly, berry transpiration rates were compared between cultivars to determine whether differences can impact berry size changes during progressive drought. It was found that 'Cabernet Franc' berries had lower rates of transpiration compared to other cultivars, and this contributed to delayed and smaller changes to berry size changes. The recently introduced “water potential curve” was also further analyzed to determine whether it can differentiate grapevine cultivars based on predawn water potential thresholds of leaf stomatal closure and turgor loss. It was found that “water potential curves” were able to accurately differentiate grapevine cultivars based on thresholds of turgor loss, but not based on thresholds of stomatal closure.

Text

2024-01-02

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/87011

Plant Science

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/