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Light Measurements (Quality) 
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| Energy at wavelengths from 400 to 800 nm is recorded by
a spectroradiometer. Here it is being used to measure the incident radiation
in the greenhouse (the sensing head is on the bench). |
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The conection between the sensor and the control
box is very vulnerable to damage and very expensive to fix. The spectroradiometer
is programmed by a handheld computer.
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| The sensor is protected by a plastic cover when not in use.
The sensor is placed under each type of plant canopy; try to ensure
that the head is level before taking readings; three spectra are recorded
for each and averaged. | |||
| After recording the spectra are downloaded into a computer.
This can show them as graphs of energy against wavelength. It can also
be used to calculate PPF by integrating energy from 400 to 700 nm and
red-far-red ratios. Light under plant canopies is typically enriched
in far-red (725 to 735 nm) relative to red (655 to 665 nm) wavelengths
and this can affect plant growth. |
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