A limiting factor is an environmental factor that restricts metabolic reactions from occurring within an organism. The 3 main limiting factors in photosynthesis are the light intensity, carbon dioxide concentration and the temperature.e.g. light intensity is important because rays of light need to activate the chlorophyll in the leaf to begin photosynthesis. However at certain point, the rate of photosynthesis does not increase. This is due to another factor, for example carbon dioxide concentration, limiting the rate.It is also important to consider that at such high light intensities some of the chlorophyll molecules may become damaged.