Limiting Factors of Photosynthesis

Photosynthesis is the process by which green plants convert light energy, usually from the sun, into chemical energy in the form of glucose. This occurs in chlorophyll-containing plant cells, primarily in leaves.
The process of photosynthesis is often represented as: Light Energy + 6CO2 + 6H2O → C6H12O6 + 6O2.
There are three primary factors which can limit the rate of photosynthesis in plants. These are light intensity, carbon dioxide concentration and temperature.
Light Intensity: The rate of photosynthesis increases as light intensity rises, up to a certain point. Beyond this point, the rate of photosynthesis becomes steady. This is because the light-dependent reactions of photosynthesis are saturated, and there is no further capacity to process additional light energy.
Carbon Dioxide Concentration: Photosynthesis also increases with greater carbon dioxide concentrations, but only to a certain level. Beyond this level, an increase in carbon dioxide does not lead to increased photosynthesis. This is likely due to other factors becoming limiting, such as light intensity or temperature.
Temperature: Like many chemical reactions, photosynthesis occurs faster at elevated temperatures, as the enzymes that facilitate photosynthesis work best in a certain temperature range. However, if temperatures become too high, the enzymes can denature and cease working effectively, which slows photosynthesis.
The “limiting factor” is the one factor that directly impacts the rate of photosynthesis because it is in the shortest supply. If the limiting factor is addressed, the rate of photosynthesis will increase.
A plant grown in a tasty or optimal environment will have a higher rate of photosynthesis compared to a plant grown in less ideal conditions.
The concept of limiting factors can be understood with the analogy of a factory production line - the slowest step in the line determines the overall speed of production. In photosynthesis, the limiting factor is the step that is proceeding at the slowest rate, and it determines the overall rate of photosynthesis.
Understanding limiting factors helps in agriculture and horticulture, where controlled environments can be created to optimise photosynthetic rate and grow plants more quickly or more densely.