Factors Affecting Photosynthesis: Two different types of factors affect the rate of photosynthesis in plants (1) External factors and (2) Internal factors.
External Factors Affecting Rate of Photosynthesis
They are as under:
(1) Light: It plays a most important role in photosynthesis, in absence of sunlight plants can not undertake the formation of food material their survival rate of photosynthesis depends upon the intensity of light. However, a very small amount of solar energy is used by plants for photosynthesis. Excessive sunlight is also harmful to plants.
(2) Water: Water makes the photosynthetic cells active and also turgid. The process of photosynthesis starts with the splitting of water into hydrogen and oxygen under the action of light and chlorophyll. However, hardly 1.0% of water is absorbed by roots and used for photosynthesis.
(3) Chlorophyll: Not applicable to fungi or saprophytes as they are parasitic, but other plants can not produce their food in absence of chlorophyll. Chlorophyll is present in plastids in the cell of the plants.
(4) Carbon dioxide: Carbon dioxide naturally found in the air is the only source of carbon. By absorbing it plants produce sugar, starch for their livelihood. But if the concentration of carbon dioxide in the air increases it is also very harmful.
(5) Temperature: Photosynthesis takes place at ambient temperature and even below the freezing point of water. Plants are growing under various conditions at different places; the optimum temperature requirement varies from place to place of location. However, plants can survive up to 45ºC.
(6) Accumulation of photosynthetic products in the assimilating cells reduces the rate of photosynthesis in plants.
Internal Factors Affecting Rate of Photosynthesis
They are as under:
(1) Chlorophyll content: This is of prime importance because more the chlorophyll content in the chloroplast, the rate of photosynthesis increases, where it gets reduced (maybe due to any reasons) the rate of photosynthesis falls. In the case of saprophytic phanerogams or fungi, there is no chlorophyll and hence these can not prepare their food using photosynthesis.
(2) Accumulation of Photosynthetic Products: Collection or storage of sugar or starch in the cells also reduces the process of photosynthesis in the cells of plants.
(3) Protoplasmic factor is also responsible for slow down of photosynthesis.
(4) In absence of oxygen, photosynthesis does not take place.
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