Light incidence over our crops will have a direct effect on yield. Photosynthesis is the most important process in plants to produce energy. But how can we relate photons of light to yield? Based on research we know now one mole of photosynthetic photons is required in order to produce one gram o dried biomass (yield). When working with plants we usually hear about the Net photosynthetic rate. The net photosynthetic rate refers to the total rate of fixation of carbon without considering the CO2 lost during respiration. This is the correct way to measure photosynthesis. When trying to link photons to yield, we need to consider that some percentage of carbohydrates will be used for plant respiration, a process that of course will affect how carbohydrates are used to produce plant biomass or yield.
A source: https://www.hortidaily.com