Seneca Polytechnic
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Plants detect wavelengths that include ultraviolet radiation (260–380 nm) and the visible portion of the spectrum (380–740 nm) which includes PAR (400–700 nm), and far-red radiation (700–850 nm).
The peak of photosynthetic efficiency (light absorption) falls in the red light and blue light spectrums of the PAR range. Red radiation (around 700nm) is considered most efficient at driving photosynthesis – especially in the flowering stage for biomass growth (important to Cannabis growers). Blue light is essential for both the vegetative and flowering stages of plant growth, but mainly for establishing vegetative and structural growth.
The radiation within a specific wavelength range (400-700 nm) that plants use for photosynthesis is called photosynthetic active radiation.
The number of micromoles per second of photons emitted by an artificial light source with a wavelength of 400-700 nm,unit: umol/s.
Corresponding to PPF is the number of micromoles per second emitted from the light source per square meter,unit umol/m2s,it’s the idea of density.
PPFD is the PPF within one square meter.