Vapour-pressure deficit the plant may dry out and die. For this reason the ideal range for VPD in a greenhouse is from 0.45 kPa to 1.25 kPa, ideally sitting at around 0.85 kPa. As a general rule, most plants grow well at VPDs of between 0.8 and 0.95 kPa. In ecology, it is the difference between the actual water vapour pressure and the saturation water vapour pressure at a particular temperature. Unlike relative humidity, vapour-pressure deficit has a simple nearly straight-line relationship to the rate of evapotranspiration and other measures of evaporation. To compute the VPD, we need the ambient (greenhouse) air
The Water Is Wide (song) true you are, and ever shall be. Our love shines clearly against the storm, Turns darkest night to brightest day, Turns turbulent waters to perfect calm, A blazing lamp to light our way. Love is the centre of all we see, Love is the jewel that guides us true, No matter what, love, you'll stay with me, No matter what, my love, I'll stay with you. The water is wide, I cannot get o'er And neither have I wings to fly, Build me a boat that can carry two And both shall row, my love and I. </poem> <poem> The