BY STEPHEN BROOKES, NPK
Science Corner:
Vapor Pressure (VPD) Deficit How does the vapor pressure deficit impact a plant’s growth and the quality of the harvests? In its most basic form, VPD is the difference between the amount of water (vapor) in a room and how much water the room can hold when it’s saturated. Knowing the VPD is essential because, at low pressure, moisture can form on the plant’s leaves and fruits, increasing its susceptibility to mold and rot. At higher pressure, the plant needs to increase its uptake of water to keep up with its water losses to the room (transpiration). When this happens, the stomata (small pores on the underside of a leaf that take in water and CO2) star t to close, and the plant will stop growing.
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