Factors affecting photosynthesis
Light
Without light, a plant cannot photosynthesize very quickly, regardless of whether there are water and CO2 or not. But overdoing light is also not a good idea. In nature, balance is crucial. But increasing the intensity of light to a prudent limit will speed up the process.
Carbon Dioxide
It happens to be the major limiting factor. The problem arises because the concentration of carbon dioxide in the air is less. Even if there is plenty of light, the plant cannot photosynthesize in the absence of sufficient amount of carbon dioxide.
Temperature
The plants are affected lesser by temperature in comparison to light and CO2. Nevertheless, if the temperature is too hot or too cold, the rate of photosynthesis is adversely affected. C4 plants have an affinity towards higher temperatures while C3 have a much lower optimum temperature.
Water
It makes its presence felt more through its effect on the plant rather than directly on photosynthesis. It is found that slight deficiency of water shows a considerable reduction in plant yield.