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
Hydride vapour phase epitaxy source materials than in MOCVD, reducing the capital equipment costs, due to the high growth rate. Developed in the 1960s, it was the first epitaxial method used for the fabrication of single GaN crystals. Hydride Vapour Phase Epitaxy (HVPE) is the only III-V and III-N semiconductor crystal growth process working close to equilibrium. That means that the condensation reactions exhibit fast kinetics: one observe immediate reactivity to an increase of the vapour phase supersaturation towards condensation. This property is due to the use of chloride vapour precursors GaCl and InCl, of which dechlorination frequency is high enough so that there