When Do Plants Respire

This is the primary question when considering plant respiration. Because plants lack specialised organs such as lungs, we can conclude that they do not breathe but, rather respire. Plants respire via lenticels and stomata (individual lenticels and stomata exist on stems and leaves), which perform the function of gas exchange.

Respiration Types

There are two types of respiration, which we classify according to the presence or lack of oxygen:

Aerobic Respiratory System

Aerobic respiration refers to respiration that happens in the presence of oxygen, as ‘air’ contains oxygen. Aerobic respiration is the process through which oxygen is used to break chemical bonds in glucose, releasing large amounts of energy. It is the primary energy source for plants. Aerobes are animals and plants that breathe using oxygen. The majority of creatures breathe aerobically.

C6H12O6+6O2 ⟶ 6CO2 + 6H2O + Energy

Without oxygen, no organism that obtains energy via aerobic respiration can exist. This is because there is no oxygen in the area; they are unable to obtain energy from the food they consume. Aerobic respiration requires more energy since it involves the entire breakdown of glucose with the use of oxygen.

Anaerobic Respiration  System

Anaerobic respiration is the process of respiration that occurs in the absence of oxygen. Carbon dioxide CO2 and alcohol are used to create incomplete oxidation of dietary components in this method (OH). Additionally, other organic compounds such as citric acid, oxalic acid, and lactic acid are generated.

This is also referred to as intramolecular respiration. In species such as yeast, some bacteria, and parasitic worms, anaerobic respiration occurs. Anaerobic animals and plants are those that can survive and produce energy in the absence of oxygen.

Glucose ⟶ Alcohol + CO2 + (Energy)

Yeast is a one-celled fungus. A single cell represents the entire organism in yeast. This technique produces a negligible amount of energy. Yeast respires anaerobically, and during this process, glucose is converted to alcohol. As a result, it is used to manufacture wine, bread, and other products.

Anaerobic respiration produces significantly less energy than aerobic respiration because anaerobic respiration is the only type of respiration that occurs in the absence of oxygen. All organisms that obtain energy by anaerobic respiration are capable of surviving in the absence of oxygen.

For example, yeast is a creature that can survive without oxygen from the air because it derives energy from anaerobic respiration. Yeast can survive without oxygen.

The significance of air temperature

Plant respiration occurs 24 hours a day but is more pronounced at night when photosynthesis pauses. The temperature must be colder at night than it is during the day, as plants can endure stress. Consider a runner competing in a marathon. The runner respires at a faster pace than a person standing still; as a result, the runner’s rate of respiration is faster and his or her body temperature rises. A similar concept applies to plants; as nighttime temperatures rise, the rate of respiration increases, and therefore the temperature rises. This action may cause floral damage and stunted plant growth.

Root Respiration

Respiration happens in plants with the assistance of roots. Within the soil, oxygenated air already exists in the crevices between the particles. This oxygen is subsequently taken into the roots via the root hairs. The roots’ hairs are in direct contact with them. Indeed, root hair is a tubular extension of the root’s exterior epidermal cells. Within the soil particles, oxygen diffuses into the root hairs. Oxygen is distributed to all areas of roots via root hairs for breathing. During the respiration process, oxygen is converted to carbon dioxide gas, which is expelled from the roots by the same root hairs that initiate the process.

If a potted plant is watered excessively for an extended period, the plant will eventually die. This is because an excessive amount of water exorcises all the air trapped between the soil particles. As a result, oxygen is not readily available to the roots for aerobic respiration. The roots of plants respire anaerobically in these situations, producing alcohol. This can be fatal to the plant. During the early stages of germination, seeds respire anaerobically because they have a seed coat that prevents oxygen from entering.

Plants respire throughout the day and night, generating carbon dioxide in the process. Though the total amount of carbon dioxide CO2 released during the day is negligible in comparison to the amount of oxygen produced during photosynthesis. As a result, one should avoid sleeping beneath a tree at night.

Stem Cell Respiration

In plants with herbaceous stems, the gas exchange happens via stomata, and the carbon dioxide CO2 produced during the process is exclusively diffused into the air via stomata. While in plants with rigid and woody stems, the gas exchange happens via lenticels. Lenticels are often loosely packed dead cells found in the bark of woody plants as small holes. These allow oxygen to diffuse into the intercellular gaps of tissues and carbon dioxide (CO2) to escape into the atmosphere, completing the process of respiration in stems.

Leaves’ Respiration

In leaves, breathing gases are exchanged via very small pores called stomata. Stomata are abundant on the plant’s bottom leaves. Each stoma contains a small pore in the centre, which is surrounded and regulated by two kidney-shaped cells called guard cells. When the stoma opens, gases are exchanged between the atmosphere and the interior of the leaf via diffusion, completing the process of respiration in leaves.

Conclusion

Root respiration is particularly critical in organic production because the root zone is densely populated with natural bacteria that transform organic nutrients into useable ions. Because these microorganisms require oxygen to function and respire, the substrate must maintain an adequate supply of oxygen for both the roots and the microorganisms. Therefore, it is a good idea to choose a growing medium with high porosity and to utilise deeper containers, as they will drain well after watering, leaving a good reservoir of air behind.