The legacy of past droughts induces water‐sparingly behaviour in Grüner Veltliner grapevines

Abstract

Abstract Drought is becoming more frequent and severe in numerous wine‐growing regions. Nevertheless, limited research has examined the legacy of recurrent droughts, focusing on leaf physiology and anatomy over consecutive seasons. We investigated drought legacies (after 2 years of drought exposure) in potted grapevines, focusing on stomatal behaviour under well‐watered conditions during the third year. Vines were subjected for two consecutive years to short‐ (SD) or long‐term (LD) seasonal droughts, or well‐watered conditions (WW). In the third year, all plants were grown without water limitation. Water potential and gas exchange were monitored throughout the three seasons, while leaf morpho‐anatomical traits were measured at the end of the third year. During droughts (1st and 2nd year), stem water potential of SD and LD plants fell below −1.1 MPa, with a consequent 75% reduction in stomatal conductance (gs) compared to WW. In the 3rd year, when all vines were daily irrigated to soil capacity (midday stem water potential ~ −0.3 MPa), 45% lower values of gs were observed in the ex‐LD group compared to both ex‐SD and ex‐WW. Reduced midrib vessel diameter, lower leaf theoretical hydraulic conductivity, and smaller stomata were measured in ex‐LD leaves compared to ex‐SD and ex‐WW, likely contributing to the reduced gas exchange. Our findings suggest that grapevines exposed to drought may adopt a more water‐conserving strategy in subsequent seasons, irrespective of current soil water availability, with the degree of change influenced by the intensity and duration of past drought events.