Red And Far Red Light - Spectrum Technologies 3412 User Manual

Red and Far Red Light

Plants sense the amount of light in the ranges around 660 na-
nometers (red) and 730 nanometers (far red), and use the ratio
between the two to direct growth. Though plants differ in the
details of their reaction, in general a low Red / Far Red ratio
results in elongation and lower leaf area compared to a higher
ratio.
The Field Scout Red / Far Red Meter measures the light in
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these two ranges, and displays the values in units of µmol m
-1
s (the number of photons in units of micromoles, striking an
area one meter square each second).
In addition, the meter displays the Red / Far Red Ratio, elimi-
nating the need for computation.
The chart below displays the spectral response of the Field
Scout Red / Far Red Meter.
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