Bud
Bud refers to a dormant, embryonic shoot structure on the grapevine that contains the potential for future vegetative growth and fruit production. Buds are formed during the growing season preceding their growth and play a central role in vine phenology, yield determination and frost sensitivity in viticulture.[1]
In the annual growth cycle of the vine, buds develop, enter dormancy, and subsequently resume growth at budburst in spring.
Bud structure
Grapevine buds are classified as compound buds, typically consisting of a primary bud accompanied by one or more secondary (and sometimes tertiary) buds. The primary bud is usually the most fertile and is responsible for the majority of crop production, while secondary buds may develop if the primary bud is damaged, for example by spring frost.[2]
Each bud contains pre-formed shoot tissues, leaf primordia and, in many cases, inflorescence initials that determine potential fruitfulness before the following season begins.
Bud initiation and fertility
Bud initiation occurs during the growing season prior to budburst, typically from shortly after flowering until veraison. During this period, environmental factors such as light exposure, temperature and vine balance strongly influence bud fertility, defined as the number of inflorescences per shoot that the bud can produce.[3]
[[Canopy management]] practices that improve light penetration, such as shoot positioning and leaf removal, are therefore critical to achieving consistent yields in the following year.[4]
Dormancy and budburst
After leaf fall, buds enter a period of dormancy during winter. Dormancy protects the bud from cold temperatures but also creates a requirement for chilling before growth can resume. Once chilling requirements are met and temperatures rise sufficiently, buds swell and open at budburst, marking the start of the new growing season.[5]
The timing of budburst is a critical factor in cool and continental climates, as early budburst increases the risk of damage from spring frosts.
Climate and management considerations
Bud development and budburst timing are strongly influenced by climate. Warmer winters and springs associated with climate change have led to earlier budburst in many wine regions, increasing exposure to frost risk despite rising average temperatures.[6]
Viticultural practices such as pruning date adjustment, site selection and frost protection measures are commonly used to manage bud-related risks and maintain yield stability.
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.
- ↑ A. J. Winkler, James A. Cook, William Mark Kliewer, Lloyd A. Lider, General Viticulture, University of California Press, December 13, 1974. ISBN 9780520025912.
- ↑ Smart & Robinson, Sunlight into Wine, Winetitles, 1991, ISBN 9781875130125.
- ↑ 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.