Answer:
The answer is that at 0°c, freezing occurs halting the process and above 35°c the plant begins to stress.
Explanation:
Photosynthesis requires movement. When the water in leaves freeze, movement cannot occur. Further, the cells may burst, causing the leaf to die. So the temperature needs to remain above freezing, which is 0°c.
Temperatures much above 35°c begin to cause stress on the plant. There are plants to do well at this temperature and above. But most prefer to not go above that.
