Context:
Against a backdrop of global warming and a probable reduction in soil water reserves during the summer, vines could in future be subjected to drought on a more regular basis.
One of the effects of drought on plants is vascular embolism: the formation of air bubbles in the plant’s water transport system.
An increase in embolism tolerance was noted on stems and leaves during the vegetative season. The fruit, however, has not yet been studied. We therefore wonder at what level of dryness emboli develop in the xylem of the fruit, and whether this phenomenon changes after veraison (the time of year when the vine undergoes profound physiological and anatomical changes: the grape swells and changes from green to bright red for black grapes, to translucent yellow for white grapes, or pinkish for gray grapes).
Study and methods:
Main question: how does cluster tolerance to embolism evolve over the course of the season?
Hypothesis: before veraison the plant prioritizes leaves (more tolerant to drought), after veraison the plant prioritizes fruit.
Methods: sample cluster-bearing branches at two sites (one kept dry, the other watered in the experimental vineyard at Leytron, Valais). During the season, measure minimum potential at both sites (at least once a month from June to September).
Obtain vulnerability curves at two times of the year, pre- and post-delivery, for three plant parts: leaf, fruit and branch, in the laboratory using the optical method (present at EPFL).
Necessary knowledge:
Commitment and motivation. Interest in vine ecophysiology. Good knowledge of English/French.
Collaborations:
Charlotte Grossiord, tenure track assistant professor; Giovanni Bortolami, scientific collaborator; Arianna Milano, research assistant.
Key words: climate change, drought, vines.
Place de travail: EPFL/ WSL Site de Lausanne, à prévoir deplacement dans le site expérimentale de l’Agroscope à Leytron (Valais).
Reférences:
Dayer S, Herrera JC, Dai Z, Burlett R, Lamarque LJ, Delzon S, Bortolami G, Cochard H, Gambetta GA. The sequence and thresholds of leaf hydraulic traits underlying grapevine varietal differences in drought tolerance. J Exp Bot. 2020 Jul 6;71(14):4333-4344. doi: 10.1093/jxb/eraa186. PMID: 32279077
Lamarque, L.J., Delmas, C.E.L., Charrier, G. et al. Quantifying the grapevine xylem embolism resistance spectrum to identify varieties and regions at risk in a future dry climate. Sci Rep 13, 7724 (2023). https://doi.org/10.1038/s41598-023-34224-6
Brodribb, T.J., Skelton, R.P., McAdam, S.A.M., Bienaimé, D., Lucani, C.J. and Marmottant, P. (2016), Visual quantification of embolism reveals leaf vulnerability to hydraulic failure. New Phytol, 209: 1403-1409. https://doi.org/10.1111/nph.13846
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