DLI (daily light integral)

DLI (Daily Light Integral) refers to the total number of photons of photosynthetically active radiation reaching a given surface over the course of a day. It is expressed in moles per square meter per day (mol m⁻² d⁻¹). Unlike the instantaneous PPFD, it takes into account both light intensity and illumination time. It helps assess whether the seedlings are receiving enough light and whether supplemental lighting is needed. When adjusting the lamps, assess DLI at the height of the plant tips and adjust the lighting duration or the distance of the lamp according to the manufacturer’s instructions.