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Transpiration of water in xylem Stoma in a tomato leaf shown via colorized scanning electron microscope The clouds in this image of the Amazon Rainforest are a result of evapotranspiration. Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers.
The CO 2 compensation point (Γ) is the CO 2 concentration at which the rate of photosynthesis exactly matches the rate of respiration. There is a significant difference in Γ between C 3 plants and C 4 plants: on land, the typical value for Γ in a C 3 plant ranges from 40–100 μmol/mol, while in C 4 plants the values are lower at 3–10 μmol/mol. Plants with a weaker CCM, such as C2 ...
The value of the photosynthetic efficiency is dependent on how light energy is defined – it depends on whether we count only the light that is absorbed, and on what kind of light is used (see Photosynthetically active radiation). It takes eight (or perhaps ten or more [1]) photons to use one molecule of CO 2.
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 inclined asymptote has a positive slope representing the efficiency of light use, and is called quantum efficiency; the x-intercept is the light intensity at which biochemical assimilation (gross assimilation) balances leaf respiration so that the net CO 2 exchange of the leaf is zero, called light compensation point; and a horizontal ...
This is done to measure leaf transpiration, and to correct CO 2 measurements. The light absorption spectrum for CO 2 and H 2 O overlap somewhat, therefore, a correction is necessary for reliable CO 2 measuring results. [2] The critical measurement for most plant stress measurements is designated by "A" or carbon assimilation rate.
Light intensity is influenced by latitudinal position and undergo daily and seasonal fluxes which will also affect the overall photosynthetic capacity of the individual. These three parameters are predictable and can be used to predetermine the general PI curve a population should follow.
UV light wavelengths range between 295 nm-400 nm and are known to induce skin and DNA damage. [3] As a result, action spectra have been used to measure the efficiency of different light wavelengths in disinfecting water, the rate and mechanism of photodegradation of folic acid in the blood, and the chirality of molecules to determine secondary ...