Study reveals grape varieties resistant to drought

Figure 3 Hierarchical clustering analysis of the 30 grapevine varieties screened based on the varietal Ψ12, Ψ50 and Ψ88 values. Vitis varieties were organized into four clusters of vulnerability to xylem embolism: low (dark green rectangle), low-to-medium (light green rectangle), medium-to-high (orange rectangle), high (red rectangle). 

Sci Rep. 2023; 13: 7724. Published online 2023 May 12. doi: 10.1038/s41598-023-34224-6

A first-ever study of the vulnerability of grapevines to drought has yielded interesting results. According to the data, Ugni Blanc (which I've not heard of) and Chardonnay counted among the most vulnerable traditional grape varieties, while Pinot Noir, Merlot, and Cabernet Sauvignon ranked among the most resilient. Syrah and Alsatian Sylvaner were also in the top third of the ranking. 

I do question the validity of their testing methods. As I understand it, they used centrifugal force to determine how twigs cut from the vines reacted to stressors. Not sure how that accurately reflects 50 days of drought. I'll have to search out the actual paper to read the methodology and the reasoning first-hand. 

Editorial note: Found the paper. 

They evaluated drought-induced xylem embolism by conducting in situ flow-centrifugation measurements in summer exclusively. They also measured xylem embolism vulnerability in stems and leaves in Cabernet Sauvignon and Syrah to assess the hypothesis of hydraulic vulnerability segmentation. This hypothesis posits that distal organs (e.g. leaves) are more vulnerable to xylem embolism than perennial organs (e.g. stems) in order for plants to protect permanent, high-investment tissues. Comparisons between organs showed that across the two varieties, leaves exhibited significantly higher vulnerability to embolism than stems. 

Sci Rep. 2023 May 12;13(1):7724. doi: 10.1038/s41598-023-34224-6.

Quantifying the grapevine xylem embolism resistance spectrum to identify varieties and regions at risk in a future dry climate

Laurent J Lamarque, Chloé E L Delmas, Guillaume Charrier, Régis Burlett, Ninon Dell'Acqua, Jérôme Pouzoulet, Gregory A Gambetta, Sylvain Delzon 

As we planted Chardonnay and Pinot Noir, one of the most and one of the least vulnerable, we'll see how this plays out with time. Right now, the Pinot vines are doing great and the Chardonnay less than great.