Unveiling winter dormancy through empirical experiments

Chilling and Heat Requirements of Temperate Stone Fruit Trees (Prunus sp.)

“…The empirical methodology to determine dormancy by monitoring shoots in forcing conditions is the unique currently available, although it was designed more than 60 years ago [23]. This method has been applied to determine chilling requirements in early [32] and recent studies [31], but it has also been used to infer the dormant stage in research aimed at studying the physiology of dormancy [6,54,59,[100][101][102]. The variability on the experimental designs among studies had often resulted in inconsistencies in the data obtained.…”

“…This approach has been widely used from early [24] to recent studies [31] that determine the chilling requirements of the cultivars. Furthermore, these experiments serve as a base for physiological studies on dormancy [6].…”

“…These will help to deal with the growing number of new cultivars and the reduction of winter cold in many areas due to global warming.Agronomy 2020, 10, 409 2 of 32 (2.4 million t in 0.4 million ha), almond (2.2 million t in 1.9 million ha) and sour cherry (1.2 million t in 0.2 million ha) [2].Stone fruit trees, like other temperate woody species, need to accumulate a cultivar-specific amount of chilling during winter to overcome dormancy and then experience warm temperatures to finally flower in spring [3][4][5]. These conditions the adaptation of species and cultivars to each region [6] and it is the main drawback for their extension to warmer latitudes [7]. Knowing the temperature requirements of a cultivar can be useful for growers to anticipate the future performance of their orchards and to design new orchards taking into account the predicted global warming [7][8][9].…”

“…It is also a key trait in breeding programs since it determines both the adaptation to different climates and the blooming and ripening dates [22]. However, the lack of a whole understanding of the process makes obtaining reliable data complex [6]. In most works, the determination of the temperature requirements of a particular cultivar consists of two phases (Figure 1): first, the establishment of the dormancy and forcing periods Agronomy 2020, 10, 409 3 of 32 ( Figure 1a), either experimentally (Figure 1a.1) [23,24] or statistically (Figure 1a.2) [25][26][27]; and the subsequent temperature quantification in both phases (Figure 1b) by using temperature-based models for chilling (Figure 1b.1) [28][29][30] and heat quantification (Figure 1b.2) [29].…”

Mild Water Stress Makes Apple Buds More Likely to Flower and More Responsive to Artificial Forcing— Impacts of an Unusually Warm and Dry Summer in Germany

“…However, some evidence suggests that chill and heat may compensate for each other under particular circumstances [27,28]. The effect of temperature on dormancy completion is commonly evaluated by experiments with shoots exposed to forcing conditions [29] or through statistical approaches applied to long-term datasets [24,30]. An accurate temperature response model would allow estimation of thermal requirements, as well as the relationship between chill and heat accumulation during dormancy.…”