اہم حقائق

• Measured in kilopascals (kPa); optimal range for most crops is 0.8–1.2 kPa
• Low VPD (high humidity): stomata close, transpiration slows, nutrient uptake drops
• High VPD (low humidity): excessive transpiration, wilting, tip burn risk
• VPD is determined by both temperature and relative humidity together
• Seedlings and clones prefer low VPD (0.4–0.8 kPa); mature plants prefer 1.0–1.5 kPa
• Controlling VPD requires coordinating temperature, humidity, and airflow together