VPD, what is it? Why do we measure it and how does it affect your plants? VPD stands for vapor pressure deficit. Now in order for you to understand VPD, you first have to understand what saturation point is. What that means is that at a certain temperature, the air can only hold in a certain amount of moisture before it reaches dew point. Dew point is when the water actually starts condensing and falling out of there.
What VPD is is measuring the current moisture in the air versus what that saturation point is. How does this affect your plants? Well, at higher rates of VPD, your plant will transpire more, meaning that you have open stemmata, more water vapor coming from the roots through osmotic pressure up and out of the plants. That means you have higher rates of uptake of water, nutrients and CO2 when you have your stemmata open at the right rate.
Now, each crop needs a different level of VPD, and in each phase, you want to have different levels of VPD as well. Through the AROYA platform, we utilize the ATMOS 14 which measures what temperature RH and VPD is at any given point in time of the day. Through this, we could actually steer the production of your plants and manage what's going on in the day to day events, and that is why we measure VPD.