Photorespiration increases due to a higher ratio of carbon dioxide (CO₂) to oxygen (O₂) and increased temperatures.
Factors Increasing Photorespiration
When plants close their stomata to conserve water, carbon dioxide levels decrease within the leaf, while oxygen levels from photosynthesis increase. This higher ratio of O₂ to CO₂ favors the oxygenation reaction by Rubisco, leading to increased photorespiration. Also, Rubisco has a higher affinity for O₂ when temperatures increase, thus increasing photorespiration.
Conditions Favoring Photorespiration
The primary conditions are:
- High Oxygen Concentration: Elevated O₂ levels within the leaf.
- Low Carbon Dioxide Concentration: Reduced CO₂ levels within the leaf.
- High Temperatures: Increased affinity of Rubisco for O₂.
| Factor | Effect on Photorespiration | Explanation |
|---|---|---|
| High O₂/CO₂ Ratio | Increases | Rubisco binds more to O₂ instead of CO₂. |
| High Temperature | Increases | Rubisco's affinity for O₂ increases, promoting the photorespiration pathway. |
Implications of Increased Photorespiration
Increased photorespiration reduces the efficiency of photosynthesis, leading to decreased carbon fixation and reduced plant growth.
