VPD (āĻā§āĻĒāĻžāϰ āĻĒā§āϰā§āĻļāĻžāϰ āĻĄā§āĻĢāĻŋāϏāĻŋāĻ) āĻšāϞ āĻŦāĻžāϤāĻžāϏ⧠āĻāϰā§āĻĻā§āϰāϤāĻžāϰ āĻĒāϰāĻŋāĻŽāĻžāĻŖ āĻāĻŦāĻ āύāĻŋāϰā§āĻĻāĻŋāώā§āĻ āϤāĻžāĻĒāĻŽāĻžāϤā§āϰāĻžāϝāĻŧ āĻŦāĻžāϤāĻžāϏ āϏāϰā§āĻŦā§āĻā§āĻ āϝ⧠āĻāϰā§āĻĻā§āϰāϤāĻž āϧāĻžāϰāĻŖ āĻāϰāϤ⧠āĻĒāĻžāϰ⧠āϤāĻžāϰ āĻŽāϧā§āϝāĻāĻžāϰ āĻĒāĻžāϰā§āĻĨāĻā§āϝāĨ¤ VPD āĻāĻĻā§āĻāĻŋāĻĻ āĻŦāĻžāώā§āĻĒā§āĻāĻŦāύā§āϰ āĻšāĻžāϰ āύāĻŋāϰā§āϧāĻžāϰāĻŖ āĻāϰ⧠â āĻĒā§āώā§āĻāĻŋ āĻļā§āώāĻŖ, āϏā§āĻā§āĻŽāĻžāĻāĻžāϞ āĻāĻāϰāĻŖ āĻāĻŦāĻ āϏāĻžāĻŽāĻā§āϰāĻŋāĻ āĻŦā§āĻĻā§āϧāĻŋāϰ āĻšāĻžāϰāĻā§ āĻĒā§āϰāĻāĻžāĻŦāĻŋāϤ āĻāϰā§āĨ¤
āĻŽā§āϞ āϤāĻĨā§āϝ
- Measured in kilopascals (kPa); optimal range for most crops is 0.8â1.2 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 (0.4â0.8 kPa); mature plants prefer 1.0â1.5 kPa
- Controlling VPD requires coordinating temperature, humidity, and airflow together