Abstract
Climate change negatively impacts viticulture through an increased frequency of extreme events such as heatwaves and droughts, as well as accelerated phenology due to higher temperatures. This thesis investigates how canopy manipulation and water management strategies can enhance the resilience of white grapevine cultivars under current and future climatic scenarios. Three experiments, one in a controlled environment and two in field, were conducted to improve existing management strategies adapted to climate change.
In the first study, young Sauvignon blanc vines were exposed to a simulated heatwave combined with progressive drought in ecotron chambers to test whether the leaf area reduction caused by apical leaf removal could mitigate stress by lowering water losses. Results showed that leaf removal reduced transpiration under well-watered conditions and improved recovery of stomatal conductance after rewatering, although it was not effective under drought conditions due to stomatal closure.
The second experiment examined the combined effects of irrigation regime and crop load on Chardonnay in a semi-arid climate. Reduced water availability decreased berry weight, yield, stomatal conductance, leaf area, and rachis conductive tissue, but increased berry soluble solids and phenolic content. In contrast, reducing crop load increased berry weight and soluble solids while lowering stomatal conductance but had negligible effects on leaf area and rachis tissue.
The final study evaluated severe trimming at veraison to delay sugar accumulation in Chardonnay and Sauvignon blanc under elevated temperatures generated by open-top chambers. Trimming slowed sugar accumulation in both cultivars, although treatment effects were more pronounced in Chardonnay.
These findings demonstrate that canopy and water management can be adapted to improve grapevine responses to new environmental conditions, with cultivar-specific and context-dependent effects, and provide practical insights for maintaining viticulture sustainable under a warming climate.