Plant processes: Difference between revisions

The cultivar constantly moves water around internally via capillary action and releases water vapor into the environment through the stomata, this is the process of transpiration. The density of stomata and how open they are will determine the rate of transpiration. The [[Temperature and Humidity#VPD|VPD]] of a plant's environment will affect its stomal response and in turn, its rate of transpiration. For higher VPD values rate of transpiration is generally higher up until a maximum threshold<ref>Plant responses to rising vapor pressure deficit, Grossiord 2020 - https://doi.org/10.1111/nph.16485</ref>. For Cannabis the maximum VPD is around 1.6kPa (Seedlings should be exposed to 0.4-0.8kPa until they are established). The rate of transpiration is also correlated to the light intensity the plant is being exposed to i.e. High light intensity equals a high rate of transpiration. Of course, the inverse correlation between humidity and rate of transpiration has been known since the 1930s.<ref>RELATIVE HUMIDITY VARIATIONS AFFECTING TRANSPIRATION, Hiram F. Thut 1938 -https://doi.org/10.1002/j.1537-2197.1938.tb09265.x</ref> Wind speed and CO₂ levels also cause a plant response that will affect the rate of transpiration.