The photosynthetic process is temperature-sensitive with optimal temperatures varying by plant species. In general photosynthesis is fastest at moderate temperatures with the rate slowing as temperature increases or decreases from the optimal. The optimal temperature for photosynthesis also varies depending on the time of day with warmer temperatures typically being optimal during the daytime and cooler temperatures being optimal at night.
There are a number of different theories about how temperature affects the rate of photosynthesis with most of the evidence suggesting that it is the rate of enzymatic reactions that is temperature-sensitive. Enzymes are proteins that catalyze chemical reactions in the cell and the photosynthetic process is dependent on a number of enzymatic reactions. The chemical reactions that make up the photosynthetic process are endothermic meaning they absorb heat from the surrounding environment. As temperature increases the enzymatic reactions of the photosynthetic process are thought to proceed more quickly leading to an increased rate of photosynthesis.
The optimal temperature for photosynthesis also varies depending on the plant species. For example C3 plants which make up the vast majority of plant species have an optimal temperature for photosynthesis of around 25°C. In comparison C4 plants which include corn and sorghum have an optimal temperature for photosynthesis of around 35°C. This difference is thought to be due to the different enzymes used in the photosynthetic process by C3 and C4 plants.
The temperature sensitivity of the photosynthetic process has a number of implications for plant growth and productivity. For example plants that are grown in cooler temperatures typically have a higher photosynthetic rate than plants grown in warmer temperatures. This difference in photosynthetic rate can be a significant contributor to the difference in growth rates between plants grown in cool versus warm climates. Additionally the temperature sensitivity of photosynthetic enzymes can help to regulate the rate of photosynthesis in response to changes in temperature allowing plants to maintain a relatively constant rate of photosynthesis as temperature fluctuates.
Overall temperature plays a significant role in regulating the rate of photosynthesis in plants. The optimal temperature for photosynthesis varies depending on the plant species with most plants requiring moderate temperatures for optimal photosynthetic rates. The rate of photosynthesis also varies depending on the time of day with warmer temperatures typically being optimal during the daytime and cooler temperatures being optimal at night. The temperature-sensitive nature of the photosynthetic process is thought to be due to the rate of enzymatic reactions being temperature-sensitive. The implications of the temperature sensitivity of photosynthesis are widespread impacting everything from the growth rate of plants to the productivity of agricultural crops.