Vapor Pressure Deficit ( VPD ) is used by growers to assess how juiceless the gentle wind is at a give minute . If the air is too dry , photosynthesis will turn back in orderliness to protect the flora from enervation . Photosynthesis is the appendage of commute sunlight , body of water and carbon dioxide ( CO2 ) into atomic number 8 and , most significantly , sugars , which are used for plant increment . grower often allow the air in their nursery to become too juiceless during the day causing their craw to close down during critical daylight hours for growth . Using VPD allows raiser to maximize their tip daylight hours for photosynthesis , ultimately lead to enceinte and fitter harvest growth .

by Harry Connor

For greenhouses , using temperature and humidness readings to monitor environmental conditions can be more complicated than most raiser actually realise . A guileful conception to understand is that increasing air temperature provide that parcel of aviation to hold more water . It also keep an eye on that decreasing air temperature results in that the air potentially hold less water . A problem arises when we equate relative humidness values at different temperatures during the class of the day ask the environmental story to be ordered .

Unlike Ceres greenhouses , indoor farm facility practice energy - intensive cooling system and heating system to keep temperatures static . Our vigor - efficient greenhouses on the other hand , employ their passive solar design to maximize incoming solar radiation . This think internal greenhouse temperatures rise and fall with the power of the Sunday take a leak relative humidity a slippery system of measurement to habituate as temperatures change throughout the mean solar day .

The board below shows what happens when we have a constant proportional humidness value for five separate scenarios and how this move plant health as temperature change . The takeout food is that using relative humidity at different temperature can be a real headache in a nursery program . So instead of track environmental conditions using temperature and relative humidity , we advocate using VPD .

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The reason we recommend using VPD is that it is main of temperature and relative humidity . VPD measures the pressure exerted by the water vapor in the gentle wind and compares it to the theoretic saturation full stop of the air . The “ deficit ” is the conflict between the genuine vapor insistence and the impregnate vaporisation pressure note value . The smaller the difference , the more moisture laden the air will be . The enceinte the difference , the drier the breeze will be .

In the table above , a VPD time value of 2 indicates gamey works stress ( big difference ) , where a VPD of 0.62 indicates a more humid environment . Plant strain mean the metabolic activity of the flora is too high . If high metabolic activity persist , the industrial plant ’s pore will close in Holy Order to prevent impairment while simultaneously stopping photosynthesis . As cultivator , we need to boost photosynthesis and avoid periods of focus .

Temperature and humidness are not useless metrics by any mean value however , new methods of psychoanalysis are always being find . If you want to be an groundbreaking grower using the latest in data analytics , or you have any questions about VPD in general , please do not waffle to contact us .

For more information : Ceres Greenhouse Solutions4760 Walnut St. , Suite 106Boulder , Colorado 80301303 - 495 - 5006[email   protected]www.ceresgs.com