This document discusses several methods for measuring the rate of photosynthesis, including dry matter accumulation, gas exchange via manometric or CO2/O2 exchange methods, and fluorescence techniques using chlorophyll, bacteria, or dyes. The gas exchange method is most commonly used today due to advantages like ability to measure leaves, plants, or forests and monitor changes frequently. Fluorescence of chlorophyll or dyes can also provide measurements but cameras are now used to create images showing fluorescence across samples.