Factors Affecting Respiration in Plants:
Respiration can be defined as the process of step-wise biological oxidation of organic molecules to release energy, which is stored in readily usable form in ATP (Adenosine Triphosphate). During the process, molecular oxygen is used, and CO2 and water are produced. Following are the main factors affecting the process of respiration-
- Oxygen- The presence of oxygen is the first and the most essential condition for respiration since this is an oxidation process. The intensity of the process is markedly affected by changes in the concentration of oxygen in the surrounding air. If the concentration goes below 5%, the process rapidly falls. With a gradual increase in oxygen concentration, there is a corresponding steady increase in the process.
- Temperature- This markedly affects the rate of respiration. The minimum rate is reached at 0°C or even at 10°C. With the rise of temperature, the rate increases and the maximum is reached at 45°C or even at 40°C. Beyond this point, protoplasm is injured and respiration decreases. The optimum temperature, however, lies between 30°C and 33°C.
- Light- The effect of light is only indirect. In bright sunlight, respiratory activity is greater than in subdued light. This may be due to the fact that in bright light stomata remain wide open and oxygen is easily and quickly absorbed.
- Supply of Water- Protoplasm saturated with water respires more vigorously than that in a desiccated condition, as in dry seeds. Thus with the supply of water the rate of respiration increases.
- Vitality of Cells- Respiration in young active cells is more rapid than in old cells. Vegetative buds, floral buds and germinating seeds respire more vigorously than older parts of the plant body.
- Carbon Dioxide Concentration- If, as a result of respiration, carbon dioxide is allowed to accumulate around the plant, respiration slows down and comes to a standstill. If this carbon dioxide is removed, respiration again goes on normally.