Differential wind impact on Malbec and Cabernet-Sauvignon xylem structure

Abstract

Argentine Patagonia, recognised as the southernmost wine-producing region in the world, frequently experiences moderate to strong winds. Wind is a key environmental factor that affects plant growth, development, and fruit yield. This study investigates how two contrasting wind conditions (exposed and sheltered) influence the xylem structure of Vitis vinifera L. cultivars Malbec (Mb) and Cabernet-Sauvignon (CS) throughout the lifespan of the vines (2011–2021). We hypothesised that wind exposure modulates xylem structure and hydraulic performance differently depending on the cultivar, based on differences in phenotypic plasticity. During the 2021 dormant season, wood cores were extracted from the main trunk of vines growing under wind exposure and sheltered sectors of the vineyard plot. The differential wind conditions were given by a poplar windbreak. The analysis focused on the response to wind intensity through different anatomical variables, including basal area increment (BAI), cumulative BAI, vessel lumen fraction (F), and vessel area relative to ring area. Climatic data were integrated to explore correlations with xylem modifications. Results showed that CS vines under wind sheltered conditions had significantly greater mean vessel area, indicating enhanced growth and potential hydraulic efficiency, whereas CS vines under wind exposure exhibited vessels with smaller diameter and higher vessel density, maintaining F values while reducing wood productivity. This pattern suggests a structural trade-off between anatomical traits such as vessel size and vessel density, which are typically associated with hydraulic efficiency and resistance to cavitation, rather than a direct assessment of hydraulic safety margin. Results also showed that Mb vines had no significant differences in radial growth but increased vessel size and F under wind conditions, reflecting a more stable and plastic hydraulic strategy. The correlations with seasonal climatic variables revealed a spatial dichotomy: while wind exposure directly shaped anatomy in wind-exposed vines (reducing vessel size, increasing density), temperature was the dominant driver influencing xylem traits in sheltered conditions. These findings provide new evidence of cultivar-specific xylem responses to wind and highlight the importance of considering the phenotypic plasticity in vineyard management. Tailored strategies may enhance vine performance and resilience in windy environments.