Temperature is an important factor in photosynthesis as an increase in temperature generally leads to an increase rate of photosynthesis. This is because the amount of carbon dioxide that a plant can absorb is increased with higher temperatures because there is a decrease in the "boundary layer resistance," which is what stops carbon dioxide from coming into plant cells. Increase in temperature have been shown to be especially dangerous for organisms that are not used to sudden shifts in temperature; for example, phytoplankton (ocean-based photosynthetic organisms) will die due to excessive growth if the temperature suddenly goes up.
Because the hydrogen and oxygen in water are two of the essential elements for photosynthesis, an increase or decrease in water is an important corollary source in photosynthesis. There is also a correlation between water and carbon dioxide: if the carbon dioxide level is raised, the amount of water that can enter the cell raises with it. However, there is a limit for most plants for the amount of water; too much water, and the plants can no longer absorb carbon dioxide, and thus photosynthesis can not happen.
Light intensity is an important corollary factor in photosynthesis. Different types of plants can absorb different types of light. The ability to absorb light comes from the chlorophyll in the plant's chloroplast. Chlorophyll is what gives land-based plants their distinctive green color; other types of photosynthetic organisms have different types of chloroplast, and thus are different colors. If the intensity of the light reaches a point where the wavelength cannot be absorbed by the chlorophyll, then photosynthesis cannot happen.
In water-based plants, the acidity (pH level) of a plant's cell's also affects its ability to absorb carbon dioxide and subsequently photosynthesize (this is not as much of a limiting factor in plant-based plants). Water-based photosynthetic organisms must get their carbon dioxide from water bubbles, and this can only be done when there is equilibrium between carbonate and bicarbonate. This equilibrium only occurs when the pH level is above 10.3, which is a relatively basic level.