Types of Stress:

• Water stress: Reduces photosynthesis.
• Heat stress: Leads to anthocyanin degradation (Mori et al., 2005-2007).
• Excess light stress: Risk of berry sunburn, especially during véraison.

Practical Solutions:

• Kaolin:
• A white clay used as a “sunscreen.”
• Recommended dose: 3 kg/hL.

Impact of Stress:

• Inhibition of polyphenol ripening (Dr. Bonelli, 2024).
• Risk of unpleasant astringent flavors in wine.

Main Components:

• Flesh: Sugars, acids.
• Skin: Color, aroma compounds.
• Seeds: Tannins.

Berry Development during Véraison:

• Shift from photosynthetic activity to a “sink” role.
• Accumulation of sugars, anthocyanins, proteins, tannins, and flavor/aroma compounds.
• Increase in pH and acid metabolism.

• Key factors influencing vine growth and berry ripening:
• Photosynthesis: Sensitive to water and heat stress.
• Light: Directly affects anthocyanin accumulation.
• Temperature: Regulates gene expression linked to ripening.

Observed Effects:

• Accelerated global warming (+1.5°C over 70 years).
• Maximum temperatures increased by up to +8°C since 1980.
• Harvests advanced by an average of 30 days compared to 1945.

Risks:

• Decoupling of phenolic and technological maturity.
• Berry dehydration and acid loss.

Vine training systems: Emphasize canopy management.

Cluster zone defoliation:

• Requires moderation to prevent berry sunburn.

Technological innovation: Use of sensors for precise vineyard management.

Anthocyanins: Pigments responsible for color.

Tannins: Influence structure and astringency of wine.

Sugars and acids: Essential for wine balance and quality.