PAR is quantified in units of photosynthetic photon flux density to correspond to the intensity of light source radiation energy per unit of the earth's surface per unit of time
PAR is quantified in photosynthesis photon flux densities to correspond to the light intensity of the light source for each unit of the Earth's surface per unit of time
Par is quantified in terms of photosynthetic photon flux density to correspond to the radiant light intensity of light source in each time unit and each earth surface unit