Management strategies to improve drought tolerance in grapevine for climate-resilient viticulture: A review

Drought stress represents a critical abiotic constraint in global viticulture, with moderate to severe water deficits leading to yield reductions of approximately 20–60%, particularly in arid and semi-arid regions. Water deficit decreases photosynthetic rates by 30–50% due to combined stomatal and non-stomatal limitations, accompanied by a 40–50% decline in stomatal conductance and substantial reductions in relative water content. Conversely, regulated deficit irrigation (RDI) can enhance berry composition, increasing total soluble solids by 2–3°Brix and anthocyanin accumulation by 15–30%, although berry size may decline by 10–20%. Rootstock genotype plays a pivotal role in drought adaptation, with tolerant rootstocks improving hydraulic conductance by 15–40% and sustaining 40–60% of yield under RDI compared to susceptible combinations. Emerging agronomic interventions, including seaweed extracts (2–4 mL L−1) and plant growth-promoting rhizobacteria, enhance antioxidant enzyme activities by 20–40%, improve water use efficiency by 20–40%, and increase yield by 15–30% under water-limited conditions. At the molecular level, drought stress induces 2–5-fold upregulation of key stress-responsive genes, including dehydrins, aquaporins, and abscisic acid-responsive transcription factors, highlighting coordinated regulatory networks governing stress perception and adaptation. This review synthesizes physiological, biochemical, and molecular insights with practical management strategies to improve drought tolerance and sustain grape production under changing climatic conditions.