spectrum of light (TABLE 1) is used by the
plant for photosynthesis, the process which
results in the production of sugars. Plants
use red and blue light most efficiently but
they also use orange and yellow light.
Plants are continually growing, producing
new chloroplasts and chlorophyll so both
spectrums of light are being used by the
plant continually. Plants reflect green light
rather than using it.
Action Spectrum of: (A) Photosynthetic
Response
(B) Chlorophyll Synthesis
Although the MH and HPS lamps emit
different color light both lamps emit high
levels of light in the critical red and blue
wavelengths. Either lamp can be used for
cultivation. HPS lamps produce faster
growth because they emit more total light
useable by the plant.
Many shop owners maintain that
combinations of MH and HPS lights
produce the fastest growth, or alternatively,
that MH units should be used for growth
and HPS units for flowering. There is no