Do plants need to breathe? – The importance of good aeration

Terrestrial plants provide a large part of the oxygen present on Earth. Oxygen is produced by the rupture of the molecule of water during photosynthesis. Even though plants are the reason we can breathe on our planet, oxygen deficiency in their root systems occurs frequently in nature.


Functions of oxygen

Oxygen is indispensable to higher plants for metabolism and growth. Just as all living beings do, plants also need to breathe. Oxygen is continuously coming in and out the plant tissues - it’s produced as a residue of photosynthesis and used as a reagent for cellular respiration.

Cellular respiration is one of the main biochemical pathways of all living beings. During this process, plants and animals convert certain organic compounds, such as glucose, into usable energy for the organism. This conversion is also called oxidation, a name that alludes to oxygen playing a key role in this process.

This usable energy is stored and can be used to drive processes requiring energy, including biosynthesis of essential molecules as proteins and sugars, and absorption and transportation of nutrients across the cells. 

Finally, oxygen is used by microorganisms that live in the soil around the roots. If these bacteria have sufficient aeration, they facilitate the absorption of nutrients by the plant and improve the quality of the substrate.

How do you recognize an oxygen deficiency in plants?

The majority of plant tissues can tolerate oxygen deficiency for short periods before suffering irreversible damage. This is why you have to pay attention to any change in the appearance or growth rate of the plant and act before it is too late. Some parts of the plants, as seeds and roots, are especially sensitive to oxygen deficiency, as they aren’t able to photosynthesize. 

An oxygen deficiency is first shown in the roots, which become brown and mushy rather than white and firm. Another more visible symptom is the fall of the leaves and their color change from pale green to yellow.

Causes of an oxygen deficiency

The main causes of lack of oxygen on the root environment are the inappropriate structure of the soil or substrate and the excess of irrigation.

  • Heavy and compact soil or substrates: If the substrate you’re using is not light enough, the oxygen is not going to reach the roots and plant will suffer a deficiency. Not only the root wouldn’t be able to breathe, but also it could lead to an excess of decomposition of organic materials with several harmful effects for the plant.
  • Excess water: Roots can be subject to oxygen deficiency soon after strong rainfall or excess of watering, since the soil usually becomes flooded for a short or longer period depending on its drainage capacity. The absence of aeration in overwet soils produces "root-rot", which is applied to cases where roots die from lack of oxygen instead of infection by fungi.

What can you do about an oxygen deficiency?

You can easily avoid an oxygen deficiency using high quality substrates that let the oxygen reach the roots and breathe freely.

If you’re growing plants in hydroponic systems, you should note that when plants’ roots are immersed in stagnant water, they become oxygen deprived and develop root rot. Hydroponic systems work best when the nutrient solution is oxygenated with an air pump as it’s delivered to the plants.

Soil-grown plants suffer from oxygen deficiency when they are over-watered. Give the soil a chance to dry out between watering and give your plants only the amount of water they can absorb in a few hours. Once a plant suffers from root rot, it’s nearly impossible to rescue it.