Fruit Bud Dormancy VS Full Tree Dormancy

Fruit Bud Dormancy

Fruit bud dormancy specifically refers to the dormant state of the mixed buds that will produce flowers and potentially fruit in the following season.

Timing: Fruit buds are initiated during the current growing season, typically in summer, for the following year's crop.

• Composition: These are mixed buds containing both leaf and flower primordia.

• Development: Fruit bud development occurs over two seasons, with floral components forming inside the buds during autumn and winter.

• Chilling Requirement: Each fruit bud has its own chilling requirement that must be met to break dormancy.

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• Chilling Requirement: Each fruit bud has its own chilling requirement that must be met to break dormancy.

Full Tree Dormancy

• Full tree dormancy, also known as winter dormancy or endodormancy, is a state that affects the entire tree.  Timing: It begins in late autumn or early winter and lasts until sufficient chilling has accumulated.

• Scope: This dormancy affects all parts of the tree, including vegetative and reproductive buds, as well as the vascular system.

• Purpose: It allows the tree to survive unfavorable winter conditions.  Full tree dormancy progresses through distinct phases:

1. Paradormancy (summer dormancy)
2. Endodormancy (deep dormancy)
3. Ecodormancy (spring dormancy)

Key Differences

• Specificity: Fruit bud dormancy is specific to reproductive buds, while full tree dormancy affects the entire tree.

• Initiation: Fruit buds begin forming in summer, whereas full tree dormancy is triggered by environmental cues like shorter days and colder temperatures in autumn.

• Duration: Fruit bud development spans two seasons, while full tree dormancy is an annual cycle.



• Breaking Dormancy: Fruit buds may have slightly different chilling requirements compared to vegetative buds1.
• Full tree dormancy release requires the accumulation of sufficient chilling for the entire tree.
• Physiological Processes: Fruit bud dormancy involves specific hormonal changes and gene expression related to flower development15.
• Full tree dormancy encompasses broader physiological changes, including alterations in water content, hormone levels, and metabolic activity throughout the tree.
• Impact on Growth: Breaking of fruit bud dormancy leads to blossom development and potential fruit set3.
• Release from full tree dormancy allows for overall growth resumption, including leaf development and shoot elongation.

Understanding these differences is crucial for orchard management, as it affects pruning timing, application of dormancy-breaking agents, and prediction of bloom and harvest times. Proper management of both fruit bud and full tree dormancy is essential for optimal fruit production and tree health in apple orchards.

REFERENCES:

Anton Milyaev, Ute Born, Elke Sprich, Michael Hagemann, Henryk Flachowsky, Eike Luedeling, Identifying indicators of apple bud dormancy status by exposure to artificial forcing conditions, Tree Physiology, Volume 44, Issue 10, October 2024, tpae112, https://doi.org/10.1093/treephys/tpae112

Meg Becker, The Phases of Bud Dormancy, Horticultural Consultant, Posted By HBFA | August 12, 2022

Wei J, Yang Q, Ni J, Gao Y, Tang Y, Bai S, Teng Y. Early defoliation induces auxin redistribution, promoting paradormancy release in pear buds. Plant Physiol. 2022 Nov 28;190(4):2739-2756. doi: 10.1093/plphys/kiac426. Erratum in: Plant Physiol. 2023 Mar 17;191(3):2066. doi: 10.1093/plphys/kiad039. PMID: 36200868; PMCID: PMC9706473.