Is acrotonic budburst pattern in spring a typical behavior of the low-chilling apple cultivar ‘Eva’ in mild winter conditions? An approach combining ex planta single-node cutting test and in planta bud water content during dormancy

• The low-chilling ‘Eva’ grown in mild winter presents an acrotonic spring budburst.
• The position of the bud on the shoot affects dormancy release.
• Spring acrotony is related to an increase of winter bud water content in planta.
• Spring acrotony is related to a decrease of mean time to budburst ex planta during winter.

Working on the low-chilling apple cultivar ‘Eva’ grown in mild winter conditions of southern Brazil, we studied the influence of bud position along the one-year-old shoot on dormancy release and water content during winter, and actual budburst in spring. Firstly, during winter, the water content measured in planta increased, and the mean time to budburst measured ex planta with the single-node cutting test decreased, for buds from the distal half of shoots whereas such trends were not observed for buds in the proximal half. These two phenomena revealed a higher growth capacity of distal buds during winter compared to proximal buds. Secondly, at spring, there was an acrotonic budburst pattern similar to that of high-chilling cultivars grown under cold winter conditions. We discuss the interest of these winter bud traits as reliable markers of the adaptation of low-chilling apple cultivar to mild winter conditions.