Maximum Yield USA 2016 June | Page 144

ARTIFICIAL LIGHTING “A grower may know how much light at certain wavelengths is hitting a square meter every second. But how many seconds of that light does the plant need? That’s the question that DLI answers.” PAR – (measured in micromoles/ sec-m2) is the measure of the photosynthetically active radiation, or the useful light energy to plants at a given point in space. A PAR measurement by itself