In greenhouses or growth chambers, DLI values are typically much lower, which can affect the shoot/root ratio, morphology, and the timing of flowering.
R/IR ratio is to check the PPFD ratio between Red part (600~700nm) and IR part (701~780nm).
R/B ratio is to check the PPFD ratio between Red part (600~700nm) and Blue part (400~499nm).
Efficiency is the value that express how well the PPFD spectrum fit the PAR action Spectrum.
The value is from 0 to 100% and it will change when the reference PAR action spectrum changes.
Original Spectrum：Vertical axis is relative intensity
PPFD Spectrum：Vertical axis is PPFD
Because PPFD is just calculated from a known spectrum but not related to plant light response. To check how efficient the light for plants, have to weight the value by required PAR action spectrum to get Yield Photon Flux Density(YPFD).
PPFD is a value that explains how many photons in specific range (it’s from 400-700nm for plant growth) of the visible light spectrum (photosynthetic active radiation or PAR) that fall on a square meter of target area per second.
Photosynthetically active radiation, often abbreviated PAR, designates the spectral range of solar radiation from 400 to 700 nm that photosynthetic organisms are able to use in the process of photosynthesis.