Differentiated dynamics of bud dormancy and growth in temperate fruit trees relating to bud phenology adaptation, the case of apple and almond trees

Abstract

Few studies have focused on the characterization of bud dormancy and growth dynamics for temperate fruit species in temperate and mild cropping areas, although this is an appropriate framework to anticipate phenology adaptation facing future warming contexts which would potentially combine chill declines and heat increases. To examine this issue, two experimental approaches and field observations were used for high- and low-chill apple cultivars in temperate climate of southern France and in mild climates of northern Morocco and southern Brazil. Low-chill almond cultivars offered an additional relevant plant material for comparison with apple in northern Morocco. Divergent patterns of dormancy and growth dynamics were clearly found in apple tree between southern France and southern Brazil. Divergences were less pronounced between France and Morocco. A global view outlined main differences in the dormancy chronology and intensity, the transition between endordormancy and ecodormancy and the duration of ecodormancy. A key role of bud rehydration in the transition period was shown. High-chill cultivars would be submitted in mild conditions to heterogeneous rehydration capacities linked to insufficient chill fulfillment and excessive forcing linked to high temperatures. This would favor bud competitions and consequently excessive flowering durations and weak flowering. Low chilling requirements in apple and almond would conversely confer biological capacities to tolerate superficial dormancy and abrupt transition from endordormancy to ecodormancy without important heterogeneous rehydration states within buds. It may also assume that low-chill cultivars can also tolerate high temperatures during ecodormancy as well as extended flowering durations.

Blooming under Mediterranean Climate: Estimating Cultivar-Specific Chill and Heat Requirements of Almond and Apple Trees Using a Statistical Approach

“…Similar results were found by Benmoussa et al [23]. Furthermore, El Yaacoubi et al [15] found that low-chill apple cultivars showed very early flowering dates compared to high-chill cultivars. However, as mean bloom dates did not differ much between the 12 apple cultivars analyzed herein, no clear relationship could be found between the CR or the length of the chill/forcing phase and their bloom dates like those we found for almond.…”

“…Furthermore, warming during the chilling phase could impede the cultivation of some species in their present locations if their CR are not met anymore [2]. In the case of temperate fruit trees, because of their need to fulfil CR to ensure homogeneous flowering and fruit set [3], the intensification of global warming may compromise the ability of many growers to satisfactorily produce the same array of crops as in the past [13][14][15]. On the other hand, such increases in temperature will allow the cultivation of species, such as citrus, that until now have been restricted because of too-low temperatures during winter.…”

Budbreak induction in kiwifruit vines cultivated in an organic system by the biological method of single node cutting

“…Dormancy, when divided into three phases (para-, endo-, and ecodormancy), has the endodormancy as crucial one, because the cold accumulation during autumn/winter period is fundamental for the plant physiological processes during this phase. However, the use of sprouting inductors can serve as a supplement (El Yaacoubi et al 2016). In this research, it can be observed that it is very important to choose the correct bud inductor and its concentration, because not all inductors and not all tested concentrations could complement the lack of coldness and consequently induce a good sprouting.…”

Analysis of the Modulation of Dormancy Release in Almond (Prunus dulcis) in Relation to the Flowering and Ripening Dates and Production under Controlled Temperature Conditions

“…Endodormancy completion is needed for the xylem vessel differentiation that allows for the rehydration of the developing bud [20]. Vegetative buds released from endodormancy could be in a dominant state and quickly grow during ecodormancy under high temperatures [21]. This could inhibit the growth of other buds by correlative inhibitions and lead to very short ecodormancy [7].…”

“…This could inhibit the growth of other buds by correlative inhibitions and lead to very short ecodormancy [7]. Additionally, it is possible that low chilling requirements cultivars such as Desmayo Largueta could better tolerate high temperatures during ecodormancy [21].…”