Chlorophyll content index
(CCI) is defined as the ratio of transmission at 940 nm
to 660 nm through a leaf. CCI units can be easily
extrapolated to transmission measurements made with
spectroradiometers and remote sensing measurements.
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SPAD
stands for Special Products Analysis
Division (a division of Minolta). As
the name implies, this is not
directly related to optical
transmission through a leaf.
Although SPAD units have come into
common use, they are not easily
extrapolated to other methods of
measuring chlorophyll and plant
health. The arbitrary SPAD units can
be converted to standard units of
optical transmission (CCI) by the
equations shown on the graph, which
were derived by measuring color
filters and leaves with both meters.
 HOW THE METER WORKS
Chlorophyll transmission is characteristically high in the near infrared range and very low in the red range because green plants absorb visible radiation for photosynthesis and transmit near infrared, which they do not use.
The CCM-200 uses LEDs that emit specific wavelengths in the red and infrared ranges. The detector analyzes the ratio of the two wavelengths to determine chlorophyll concentration index (CCI).
For an example showing a leaf transmission spectrum and CCI calculation, click here  |
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CCI UNITS
Chlorophyll concentration index (CCI) is defined as the ratio of transmission at 931 nm to 653 nm through a leaf.
The CCM-200 uses calibrated LEDs and receptors to calculate the CCI in samples. With a spectroradiometer, the entire transmission spectrum of a leaf can be measured.
CCI measurements can easily be made with a spectroradiometer, see graph , in addition to other applications. |
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CONVERTING FROM SPAD UNITS
SPAD stands for Special Products Analysis Division (a division of Minolta). As the name implies, this is not directly related to optical transmission through a leaf.
Although SPAD units have come into common use, they are not easily extrapolated to other methods of measuring chlorophyll and plant health.
Click on the graph to see the equations for converting from the arbitrary SPAD units to standard units of optical transmission (CCI). These were derived by measuring color filters and leaves with both meters. |
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