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Stomatal conductance, usually measured in mmol m −2 s −1 by a porometer, estimates the rate of gas exchange (i.e., carbon dioxide uptake) and transpiration (i.e., water loss as water vapor) through the leaf stomata as determined by the degree of stomatal aperture (and therefore the physical resistances to the movement of gases between the air and the interior of the leaf).
The stomatal conductance g s accounts for the effect of leaf density (Leaf Area Index), water stress, and CO 2 concentration in the air, that is to say plant reaction to external factors. Different models exist to link the stomatal conductance to these vegetation characteristics, like the ones from P.G. Jarvis (1976) [4] or Jacobs et al. (1996 ...
Stomatal resistance (or its inverse, stomatal conductance) can therefore be calculated from the transpiration rate and humidity gradient. This allows scientists to investigate how stomata respond to changes in environmental conditions, such as light intensity and concentrations of gases such as water vapor, carbon dioxide, and ozone . [ 11 ]
Since photosynthesis, transpiration and stomatal conductance are an integral part of basic plant physiology, estimates of these parameters can be used to investigate numerous aspects of plant biology. The plant-scientific community has generally accepted photosynthetic systems as reliable and accurate tools to assist research.
The CO 2 concentrating mechanism also maintains high gradients of CO 2 concentration across the stomatal pores. This means that C 4 plants have generally lower stomatal conductance, reduced water losses and have generally higher water-use efficiency. [2]
By definition, stomatal conductance, measured in mmol m⁻² s⁻¹, is the measure of the rate of passage of carbon dioxide (CO2) exiting, or water vapor entering through the stomata of a leaf. Stomata are small pores on the top and bottom of a leaf that are responsible for taking in and expelling CO2 and moisture from and to the outside air.
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Closing of the stomata also slows the rate of transpiration, which limits water loss and helps to prevent the wilting effects of moisture stress. [5] This closing can be triggered by the roots sensing dry soil and in response producing the hormone ABA which when transported up the xylem into the leaves will reduce stomatal conductance and wall ...