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Typical examples include the Leaf Area Index, biomass, chlorophyll concentration in leaves, plant productivity, fractional vegetation cover, accumulated rainfall, etc. Such relations are often derived by correlating space-derived NDVI values with ground-measured values of these variables.
The reaction begins with the excitation of a pair of chlorophyll molecules similar to those in the bacterial reaction center. Due to the presence of chlorophyll a, as opposed to bacteriochlorophyll, Photosystem II absorbs light at a shorter wavelength. The pair of chlorophyll molecules at the reaction center are often referred to as P680. [1]
Also, the chlorophyll concentration can be estimated by measuring the light transmittance through the plant leaves [29]. The assessment of leaf chlorophyll content using optical sensors such as Dualex and SPAD allows researchers to perform real-time and non-destructive measurements [30] [31]. Research shows that these methods have a positive ...
The daily light integral (DLI) is the number of photosynthetically active photons (photons in the PAR range) accumulated in a square meter over the course of a day. It is a function of photosynthetic light intensity and duration (day length) and is usually expressed as moles of light (mol photons) per square meter (m −2) per day (d −1), or: mol·m −2 ·d −1.
Relationships between Trophic State Index, chlorophyll, phosphorus, Secchi depth, and trophic class (after Carlson 1996) [4] Trophic State Index Chlorophyll (μg/L) Phosphorus (μg/L) Secchi depth (m) Trophic Class < 30—40 0—2.6 0—12 > 8—4 Oligotrophic or hipotrophic 40—50 2.6—7.3 12—24 4—2 Mesotrophic 50—70 7.3—56 24—96
Chlorophyll-a concentration is sometimes used to measure water clarity, especially when suspended sediments and colored dissolved organic matter concentrations are low. Chlorophyll-a concentration is a proxy for phytoplankton biomass, which is one way to quantify how turbid the water is due to biological primary production .
Chlorophyll a is a common measure of primary production, as it is a main component of photosynthesis. [ 1 ] [ 3 ] [ 2 ] Primary production is often measured using three variables: the biomass (or amount in weight) of the phytoplankton, the availability of light, and the rate of carbon fixation. [ 2 ]
Some plants have evolved mechanisms to increase the CO 2 concentration in the leaves under these conditions. [ 30 ] Plants that use the C 4 carbon fixation process chemically fix carbon dioxide in the cells of the mesophyll by adding it to the three-carbon molecule phosphoenolpyruvate (PEP), a reaction catalyzed by an enzyme called PEP ...