Dormancy
Dormancy is a physiological resting phase in the annual growth cycle of the grapevine, during which visible growth ceases and metabolic activity is greatly reduced. From a viticultural and wine perspective, dormancy is essential for vine survival, carbohydrate balance and the regulation of subsequent growth stages, directly influencing budbreak, yield potential and long-term vineyard performance.[1]
Definition and phases
Dormancy in grapevines occurs after leaf fall in autumn and extends through winter until the resumption of growth in spring. It is commonly divided into two overlapping phases: endodormancy and ecodormancy. Endodormancy is internally regulated within the bud and cannot be broken even under favourable conditions, while ecodormancy is imposed by external environmental factors, primarily low temperature.[2]
The transition from dormancy to active growth requires exposure to sufficient winter chilling, followed by warmer spring temperatures that trigger budbreak.
Physiological role
During dormancy, the vine reallocates and conserves energy. Carbohydrate reserves accumulated during the growing season are stored in the trunk, roots and perennial wood, providing the primary energy source for early spring growth before photosynthesis resumes.[3]
Bud tissues undergo physiological changes that increase cold hardiness, enabling vines to survive winter conditions. Proper dormancy is therefore critical for vine longevity and resilience.
Viticultural significance
Dormancy is the period during which key vineyard operations take place, most notably pruning. Pruning timing during dormancy influences vine vigour, yield balance and susceptibility to spring frost. In cooler climates, delayed pruning is sometimes used to postpone budbreak and reduce frost risk.[4]
Dormancy also affects the uniformity of budburst. Inadequate chilling can lead to irregular or delayed budbreak, resulting in uneven shoot development and ripening.
Climate and dormancy
Dormancy is strongly influenced by temperature. Many grape varieties require a minimum accumulation of winter chill to exit endodormancy successfully. Warmer winters associated with climate change have raised concerns in some regions about insufficient chill accumulation, potentially disrupting phenological timing and reducing yield consistency.[5]
Such changes may necessitate adaptations in site selection, variety choice and vineyard management strategies.
Historical and regulatory context
Traditional viticultural calendars in many wine regions are structured around dormancy, reflecting its central role in the vine’s annual cycle. Regulations governing pruning dates and vineyard operations in some appellations are designed to align with dormancy to protect vine health and manage production risks.[6]
See also
References
- ↑ Jancis Robinson, Oxford Companion to Wine, Oxford University Press, 17 Sept. 2015. ISBN 9780198705383.
- ↑ Michael G. Mullins, Alain Bouquet, Larry E. Williams, & 0 more, Biology of the Grapevine, Cambridge University Press, July 30, 2007. ISBN 9780521038676.
- ↑ Pascal Ribéreau-Gayon, Yves Glories, Alain Maujean, Denis Dubourdieu, & 1 more, Handbook of Enology, Volume 2: The Chemistry of Wine - Stabilization and Treatments, Wiley, 31 Mar. 2006. ISBN 9780470010372.
- ↑ Markus Keller, The Science of Grapevines: Anatomy and Physiology, Academic Press Inc, 19 Jan. 2015. ISBN 9780124199873.
- ↑ Jones et al., Climate Change and Global Wine Quality, Wiley, 2012, ISBN 9781118450048.
- ↑ Unwin, Wine and the Vine, Routledge, 1991, ISBN 9780415042698.