. What are the Factors Affecting Photosynthesis

Best Answer

The Factors are :

1. Light

Out of the total solar energy  reaching to the earth about 2% is used in photosynthesis & about 10% is used in other metabolic activities. Of the total light falling on a leaf, about 80% is absorbed, 10% is reflected & 10% is transmitted. Under low light intensity, the rate of photosynthesis is low. Increase in light intensity causes increase in the rate of photosynthesis. At very high light intensity beyond a certain point of photosynthetising cells exhibit photo-oxidation.


Some plants require low light intensity for optimum photo synthesis, called Sciophyte. On the other hand, plants require high light intensity are called heliophyte.

Maximum photosynthesis has been done in red light than in blue light. The green light has minimum effect.

Generally, if the plants get 10 to 12 hours light per day it favours good photosynthesis.

2. Carbon Dioxide 

Carbon dioxide is the major limiting factor for photosynthesis. The concentration of CO2¬ is very low in the atmosphere (between 0.03 and 0.04 per cent). Increase in concentration upto 0.05 per cent can cause an increase in CO2 fixation rates; beyond this the levels can become damaging over longer periods.

The fact that C3 plants responds to higher CO2 concentration by showing increased rates of photosynthesis leading to higher productivity has been used for some greenhouse crops such as tomatoes and bell pepper. They are allowed to grow in carbon dioxide enriched atmosphere that leads to higher yields.

3. Temperature

Usually the rate of photosynthesis increases in temperature upto 40ºC. Above this temperature, there is a decreases in the rate. High temperature results into the deactivation of enzymes & thus, the dark reaction is affected. The C4 plants respond to higher temperature & show higher rate of photosynthesis while C3 plants have a much lower temperature optimum.

4. Water

Water is an essential raw material in photosynthesis. This rarely, acts as a limiting factor because less than 1% of the water absorbed by a plant is used in photosynthesis. However, lowering of photosynthesis has been observed if the plants are inadequately supplied with water.

5.  Oxygen and Minerals

Excess amount of oxygen has been shown to inhibit photosynthesis in C3 plants that exhibit photorespiration.

Deficiency of minerals (viz., Mg, Fe, Cu, Cl, Mn, P etc.) reduce rate of photosynthesis.








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