In regards to what nutrition does a plant receive from light spectra, there are two general different types of photosystems: II & I. Both occur as reaction centers in chlorophyll a and are designated as P680 and P700 (respectively).
Absorption at 680 and 700 nm is the numerical part of that. The p is for phytochrome. The is the beginning of the photolysis of water to generate ATP.
How intensity plays a part, look up: action spectrum of photosynthesis.
Last edited by DPfarr; 08-13-2019 at 11:26 PM.