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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 ]
Let K 0 is the normal conductivity at one bar (10 5 N/m 2) pressure, K e is its conductivity at special pressure and/or length scale. Let d is a plate distance in meters, P is an air pressure in Pascals (N/m 2 ), T is temperature Kelvin, C is this Lasance constant 7.6 ⋅ 10 −5 m ⋅ K/N and PP is the product P ⋅ d/T .
Resistance to drought is a quantitative trait, with a complex phenotype, often confounded by plant phenology. Breeding for drought resistance is further complicated since several types of abiotic stress, such as high temperatures, high irradiance , and nutrient toxicities or deficiencies can challenge crop plants simultaneously.
Canopy conductance, commonly denoted , is a dimensionless quantity characterizing radiation distribution in tree canopy.By definition, it is calculated as a ratio of daily water use to daily mean vapor pressure deficit (VPD). [1]
Short-term radial growth variations, on the other hand, were considered to be due mainly to physiological acclimatisation, with response to factors such as stomatal conductance regulation, variation of photosynthetic capacity, and respiration. Nevertheless, it is clear that the adaptations are linked, and that radial growth is the integrative ...
Due to presence of carbon dioxide, a rapid acidification of cytoplasm takes place leading to stomatal closure. Milbarrow (1974) has described the formation of these chemicals in the chloroplast. It moves to the stomata, where it is responsible for checking the intake of Potassium ion or induces loss of potassium ion from the guard cells.