Is grapevine endodormancy already over in the Northern hemisphere?Yes 💪 , depending on the wine regions !

Viticulture professor retired from the Agro-Institute (Montpellier) since août 3, 2023

The data (from the attached figure) illustrates that, in the Hérault wine region of France, as of janvier 10, 2024, there have been 16 days since novembre 1, 2023, with average temperatures below +8°C. This cumulative temperature has triggered the end of dormancy.

The vine is now in ecodormancy. 😊

But what is grapevine dormancy? 🤔

The key stages of bud dormancy, as outlined by Lang et al. (1987) and Horvath et al. (2003), include:
• Endodormancy 😴 : This stage involves the inhibition of growth originating within the bud meristem, requiring chilling before growth can resume. In a vineyard, latent bud endodormancy initiates on a primary shoot during lignification, a process that can begin from July/August onwards in the northern hemisphere.
Cold temperatures are essential for breaking dormancy, typically requiring around 250 hours at +8°C (approximately 10 non-consecutive days).

• Ecodormancy (Quiescence, Imposed Dormancy, or Winter Dormancy): This stage occurs due to insufficient environmental factors to support growth. 🌞 🌡 🌧

From now onwards, in wine regions for which the 250 hours at +8°C have been achieved, vines are in the ecodormancy stage.

What factors are needed for latent buds to develop? 👩‍🏫

• Temperature 🌡 : Both air and soil-root temperatures play a crucial role. A minimum air temperature of 10-15°C and a minimum soil temperature of 10-15°C are necessary for grapevine budburst.
• Water 🌧 : Strong water constraints should be avoided before and during budbreak and until flowering.
• Grape Varieties 🍇 : The timing of budbreak (for the same macroclimate) depends on the grape variety. For example, Chardonnay tends to bud earlier than Cabernet Sauvignon.

More in :
– Horvath et al. 2003). Knowing when to grow: signals regulating bud dormancy, Trends in Plant Science, 11, 534-540.
– Lang et al., 1987). Endo-, para-, and ecodormancy: physiological terminology and classification for dormancy research, Hortic. Sci. 22, 371-377.
– Pellegrino A., Rogiers S., Deloire A., 2020. Grapevine Latent Bud Dormancy and Shoot Development, IVES Technical Reviews, https://lnkd.in/eiWYAuAW