Young grapevines exhibit interspecific differences in hydraulic response to freeze stress but not in recovery

This study demonstrated that freeze-induced hydraulic failure varies between two Vitis species that have different xylem vessel frequency and grouping. However, seasonal recovery of young grapevines was similar between the species. Sub-freezing temperatures after budburst represent a major threat for the cultivation of fruit crops in temperate regions. Freeze stress might disrupt xylem hydraulic functionality and plant growth; however, it is unclear if hydraulic traits influence the ability of woody plants to cope with freeze stress. We investigated if a grapevine species (Vitis hybrid) with earlier budburst had anatomical traits that cause higher freeze-induced hydraulic failure but also confer a greater ability for seasonal recovery compared to a Vitis vinifera species. Two-year-old Vitis hybrid and vinifera grapevines were container-grown outdoors, assigned to either a control (n = 40) or a freeze-stressed (n = 40) treatment and exposed to a controlled-temperature (- 4 °C) freeze stress shortly after budburst. We found that the Vitis hybrid had greater stem-specific hydraulic conductivity (K_s) and was more vulnerable to freeze-induced embolism compared to the V. vinifera species, which exhibited a less efficient but safer water transport strategy. Seventy-two hours after the freeze stress, K_s of freeze-stressed V. vinifera was 77.8% higher than that of the control, indicating hydraulic recovery. While the two species did not differ in xylem vessel diameter, Vitis hybrid exhibited higher vessel frequency and percentage of vessel grouping, which could explain its higher K_s and greater freeze-induced K_s loss compared to the V. vinifera vines. While the two species varied in the short-term hydraulic response, they exhibited similar and full hydraulic and vegetative recovery by midseason, including bud freeze tolerance during the following fall and mid-winter.