Rising temperatures and water scarcity due to climate change are significant challenges
for Mediterranean viticulture, particularly in the Douro Valley, a prominent winemaking region.
Silicon (Si) has gained attention as a potential solution for mitigating these environmental stresses,
especially in areas with limited water resources. This study explores the foliar application of Si
as a promising strategy to reduce water requirements in vineyards, specifically for the Touriga
Franca variety, thereby supporting more sustainable water use. Four treatments were tested: nonirrigated
control (C−), an irrigated control under a deficit irrigation regime (25% ETc; C+), and two Si
concentrations (7% Si-Si1 and 20% Si-Si2) applied to non-irrigated plants. Results demonstrate that Sitreated
plants improved physiological resilience, as evidenced by enhanced photosynthetic efficiency,
greater water-use efficiency, and higher biochemical quality in both leaves and berries. Additionally,
Si application increased leaf flavonoids and simultaneously improved must composition due to its
overall influence on vine physiology, indicating its potential as a sustainable alternative to irrigation
for reducing summer stress. This research suggests that foliar Si application could be a valuable,
eco-friendly strategy to support sustainable viticulture under increasingly arid conditions, reducing
the irrigation needs.
