Kiwifruit Adaptation to Rising Vapor Pressure Deficit Increases the Risk of Kiwifruit Decline Syndrome Occurrence

Kiwifruit has, for a long time, been widely affected by a syndrome named "kiwifruit decline syndrome" (KiDS). Several environmental factors have already been investigated looking for the possible origin of this syndrome. Recently, a possible role of climate change has been proposed, highlighting the influence of high air and soil temperature. In this work, the role of rising vapor pressure deficit (VPD) was also investigated in an experimental orchard in which several agronomic practices were examined in order to find strategies to face KiDS occurrence in crops. Stomatal control in response to rising VPD showed to be lacking, and root xylem vessel size and number modifications were observed as an adaptation to water stress; then, a scarce prospect of success facing sudden and strong weather events related to climate change can be expected in this plant. None of the agronomic strategies tested, that were focused on the soil quality improvement and on prevention of desiccation, avoided the KiDS occurrence. Agronomic management should move to new practices focused on orchard climate control.