The Rate of photosynthesis.
Rate of photosynthesis: The speed at which photosynthesis occurs.
The rate of photosynthesis is affected by: The intensity of light
The volume of Carbon Dioxide
Plants also need water but if a plant is so short of water it becomes the limiting factor in photosynthesis, it's already in huge trouble.
Any of the three factors can become the limiting factor:
Stops photosynthesis from happening any faster
Enviromental conditions effect which factor is limiting:
Night: No light
Winter: Temperature- Too cold
Warm and Bright: Carbon dioxide- limiting