The Daily Light Integral (DLI) is is the amount of PAR received each day as a function of light intensity (instantaneous light: μmol·m -2 ·s -1 ) and duration (day). It is expressed as moles of light (mol) per square meter (m -2 ) per day (d -1 ), or: mol·m -2 ·d -1 (moles per day).