NOTE: This definition was changed in RP-16-17 Addendum 4. Deletions have a strike-through. New text is bold.
Photon flux in the wavelength band 400 to 700 nm.
The spectral range (waveband) of radiation, from 400 to 700 nm, which be definition photosynthetic organisms are able to use in the process of photosynthesis. The measure result of PAR can be reported as photosynthetic photon flux (PPF) or photosynthetic photon flux density (PPFD).« Back to Definitions Index