What is Regulated Deficit Irrigation (RDI)?

• A. Irrigation that applies maximum water throughout the season.
• B. Irrigation used only during dormancy.
• C. A system of timing and regulating irrigation to impose mild to moderate water stress for a specified time.
• D. Irrigation that avoids any plant water stress.

Answer: (C)

Regulated Deficit Irrigation is a planned watering approach where irrigation is timed and controlled to create a mild to moderate water deficit for a defined period. The idea is to stress the vines just enough during specific growth stages to influence fruit development and quality—often improving flavor compounds, sugars, and acidity while conserving water. It’s not about flooding the vines with water, nor about watering only during dormancy, nor about avoiding any stress entirely. Instead, it intentionally applies controlled stress at key times to achieve a balance between vine health, yield, and grape quality.