Title: Factors Affecting Photosynthesis - QforQuestions
Headings: Factors Affecting Photosynthesis
Factors Affecting Photosynthesis
Factors Affecting Photosynthesis
External factors:
Light
Temperature
Carbon dioxide
Oxygen
Water
Internal factors
Chlorophyll
Age of leaf:
Protoplasmic factor
Photosynthetic products
Internal structure of leaf
Blackman’s law of limiting factor:

Content: Leaves with Kranz anatomy are more efficient in photosynthesis. Blackman’s law of limiting factor: F. Blackman (1905) stated that “when a process is conditioned as to its rapidity by a number of separate factors, the rate of the process is limited by the pace of the slowest factor. ” This law is termed as Blackman’s law of limiting factor. It can be explained by the following example. Suppose a leaf is subjected to a light intensity, sufficient for the assimilation of 5 mg carbon dioxide per hour. Under these conditions, if a plant is supplied with only one 1 mg of carbon dioxide, the rate of photosynthesis would be limited by carbon dioxide (because concentration of carbon dioxide is less than what can be assimilated in the available intensity of light). Now if the carbon dioxide concentration is gradually increased, the rate of photosynthesis will also increase correspondingly until the assimilation rate of 5 mg carbon dioxide per hour has been reached. However, further increase in carbon dioxide concentration, i.e., more than 5 mg per hour will not increase the rate of photosynthesis. This is because the light now becomes the limiting factor.