Respiration is the process by which living organisms produce energy through the oxidation of organic substances. There are two types of respiration: aerobic respiration, which requires oxygen, and anaerobic respiration, which does not. Respiration is affected by both external factors like temperature, oxygen, light, water, and carbon dioxide as well as internal factors such as food materials, the age of cells, enzymes, and inorganic salts. The rate of respiration is optimal between 20-45°C and can be reduced by low oxygen, water scarcity, or low carbon dioxide levels.

2. PIR MEHR ALI SHAH AAUR
Department of Agronomy
Course Number : AGR 501
Course Title : Crop Physiology

3. Submitted To : Dr.Imran Baloch
Submitted By : M.Younis Asghar
Arid Number : 20- Arid-2935
Assignment : AGR -501
Topic : Respiration and Factors Affecting
Respiration

4. What is Respiration?
Process in living organisms involving the production of
energy, typically with the intake of oxygen and the release of
carbon dioxide from the oxidation of complex organic
substances.

6. Types of respiration:
● Aerobic Respiration:
Takes place in the presence of oxygen.
● Anaerobic Respiration:
Takes place in the absence of oxygen

7. Factors Affecting Respiration:
Affecting Factors may either be external or internal:
External Factors:
❖ Temperature
❖ Oxygen
❖ Light
❖ Water
❖ Carbon Dioxide

8. Internal Factors:
❖ Food Material
❖ Age of Cell
❖ Enzymes
❖ Inorganic Salts

9. External Factors:
1. Temperature: Below 20¡C and above 45¡C the rate of respirationreduces. The
optimum temperature for respiration is 20¡C - 45¡C.
2. Oxygen: If the amount of oxygen is reduced the rate of respiration willreduce.
3. Water: Optimum supply of water maintains the rate of respiration normal.Rate of
respiration reduces for scarcity of water.

10. External Factors:
4. Light: The stomata opens in light, so rate of respiration comparatively high in
day time.
5. Carbon dioxide: With the increase of CO2in air, rate of respiration decreases
slightly.

11. Internal Factors:
1. Food materials: During respiration food materials break to release water and CO2.
So the quality and quantity of food materials in the cell regulates the rate of
respiration.
2.Age of cell: Rate of respiration is maximum in young cells especially in
meristamatic cells (as there is much protoplasm).
3.Enzymes: Different reactions of respiration need different kinds of enzymes.The
process completely depends on their presence.

12. 4. Inorganic salts:
Rate of respiration increases if there is more inorganic salts in the cell.
Other Factors:
❖ Various chemicals, such as cyanides, azides and fluorides, have been
reported to possess respiration retarding properties through their effect on
respiratory enzymes.
❖ Respiration rate may likely be accelerated by low concentrations of the
compounds like ethylene, carbon monoxide, chloroform and ether.