CEA VENTILATION The importance of CANOPY Managing vapor pressures in controlled environment agriculture BY WALTER STARK P 28 lant growth reacts positively or negatively to the vapor pressure deficit (VPD) - the difference between the leaf vapor pressure (LVP) and the surrounding cultivation room vapor pressure (RVP). It begins with the release of water vapor through tiny pores on the leaves called stomata. Low vapor pressure surrounding the leaf pulls water upward through JULY 2024 GPNMAG.COM FEBRUARY 2024 GPNMAG.COM the plant. The vapor pressure difference, the VPD, is the force that governs water movement through a plant and results from deducting the RVP from the LVP. The CEA industry continuously seeks to improve a crop's outcome. However, within the realm of climate control for plant life, advancing the key factor of canopy ventilation (CV) gets little attention. Without adequate CV, heat and humidity get trapped in the canopy foliage. The entire process improves when the heat and humidity are driven from the canopy foliage and processed by the HVAC system. Cultivating room vapor pressure is a fixed value based on temperature and relative humidity (RH). LVP is a function of the leaf surface temperature (LST) and RH. The RH ofhttp://www.GPNMAG.COM