Factors Affecting the Rate of Photosynthesis

Photosynthesis is a process used by plants to convert light energy, usually from the sun, into chemical energy that can be used to fuel the plant’s activities. The rate of this process can be influenced by several key factors.
Light intensity: The intensity of light striking the surface of a plant directly influences the rate at which photosynthesis occurs. As light intensity increases, the rate of photosynthesis initially increases. But at a certain point, the plant’s other variables such as carbon dioxide levels and temperature will limit the rate of photosynthesis.
Carbon dioxide concentration: Plants absorb carbon dioxide from the surrounding air. The more carbon dioxide available, the more the plant can photosynthesise, up to a limit. Beyond this limit, other factors such as light intensity and temperature limit the process.
Temperature: While higher temperatures can increase the rate of reactions involved in photosynthesis, excessive heat can denature enzymes involved in the process which can slow down or stop photosynthesis.
Water availability: Plants need water for photosynthesis. A shortage of water can slow down or halt the process. Most plants control their water loss by closing their stomata (small openings on leaves) when water is scarce, but this also limits the intake of carbon dioxide possibly affecting photosynthesis.
Chlorophyll concentration: Chlorophyll is the pigment in plants that absorbs sunlight and uses its energy to synthesise carbohydrates from carbon dioxide and water. Therefore, the quantity of chlorophyll within plant cells will directly affect the rate of photosynthesis.
Presence of accessory pigments: Plants also contain accessory pigments like carotenes and xanthophylls that can absorb light of different wavelengths and pass the energy to chlorophyll. The presence and concentration of these pigments can further increase the efficiency and rate of photosynthesis.

Remember, all these factors are interdependent, and changing one can affect how others influence the rate of photosynthesis.

Learning to identify and understand how these variables influence photosynthesis rate is important to better understand this process and its impacts on plant growth and productivity.