Buds of deciduous tree crops enter winter dormancy in response to shorter photoperiods and lower temperatures in the fall. Winter dormancy comprises successive phases of endodormancy and ecodormancy. The transition from endodormancy to ecodormancy requires the exposure of dormant buds to a certain amount of chilling temperatures, whereas heat accumulation in ecodormant buds is essential for the successful shift from dormancy to active growth in tree crops (Lang et al., 1987). While bud dormancy allows plants to withstand harsh winters, timely bud break ensures their successful regrowth and production. As such, the initiation, progression, completion, and regulation of bud winter dormancy and break have been widely recognized for their importance in the survival and productivity of tree crops. However, climate change, often associated with warmer winters and temperature fluctuations (Inouye, 2022; Grossman, 2023), poses significant challenges to these processes, as alterations in temperature patterns can disrupt the delicate balance in temperature necessary for optimal bud dormancy and break.

This Research Topic centers on the biochemical, genetic, physiological, and environmental regulation of bud winter dormancy and its break in various woody perennials, with a focus on the impact of climate change. It also explores breeding strategies to adapt to climate change, particularly rising winter temperatures. The eight articles encompass studies conducted on three continents, covering a range of crops including nut, fruit, ornamental, and beverage crops. They are briefly highlighted below.

Gabay and Flaishman reviewed recent advancements in genetic and genomic resources as well as roles of genes, phytohormones, and metabolites related to dormancy regulation in pear (Pyrus spp.). They discussed the need for developing new pear cultivars with low chilling requirements and the challenges in pear breeding due to extended juvenility. They further emphasized the importance of understanding the genetic and physiological factors controlling bud dormancy in pear breeding. To this end, they pointed out the utility of quantitative trait loci (QTLs) in understanding dormancy regulation and developing genetic markers for marker-assisted selection in breeding. Lastly, the authors suggested Mediterranean climates could be used to simulate future temperate region climates for pear breeding.