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Saturday, June 29, 2024 Matt D. Connecticut

Entry 83 of 116  
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Vapor Pressure Deficit- Deep Dive Part 2 or 2

Here is what the readout on the Affinity VPD Gun looks like. While it is nice to see these numbers taken at a random time just to show that it looks like for representative purposes. It is important to know that the handheld devise should be kept in the growing environment for a little while before taking reading so the ambient air and humidity can be accurate. However, based on my findings it is not a simply plug and play device. Other pieces of equipment to compare temperature and humidity against is key to dialing in this handheld tool. I find this calibration step is not often performed by growers and I feel no information is better than wrong information.

VPD is not something to overly get concerned with as there is only so much a grower has control over. Simply take-home message is that as temperatures increase keeping humidity at 60% or greater is important to help reduce the plant stress. Getting good coverage over the growing area is a challenge, but the misting system shown previously on my June 2nd, 2024 posting does offer an example of a simple and effective method.

Great article listed and linked below but full text is copyrighted. However, the over simplified answer is keeping the relative humidity at or above 60% during the day.

Effect of vapor pressure deficit on growth and water status in muskmelon and cucumber
https://www.sciencedirect.com/science/article/abs/pii/S0168945220303617?via%3Dihub

VPD Thermometer, Handheld Environmental Monitor, Captures Leaf VPD and Temperature :
https://acinfinity.com/content/TRV2404X1_240422_VPD%20Thermometer%20Manual.pdf?_ga=2.225954714.1886154692.1720723688-1452909769.1718573613&_gac=1.229322280.1719705546.EAIaIQobChMInI2-rIKChwMVTmFHAR0JjQVMEAQYASABEgKh__D_BwE
 



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