* Uptake of carbon dioxide: Since carbon dioxide is important in the light-independent reactions of photosynthesis, its consumption by plants can be measured as a means to determine the rate of ATP and electron carriers used for carbon fixation.
* Production of oxygen: Aquatic plants release bubbles of oxygen when they carry photosynthesis. e.g. these bubbles are collected; their volume can be measured.
* Increase in Biomass: If batches of plants are harvested at a series of times and their biomass determined, then the rate of photosynthesis can be determined by an increase in biomass.