Although plants can grow in a variety of environments, there are several conditions which might not allow them to grow or thrive successfully.
One of those is anoxic soil. Anoxic soil refers to soil environments that do not have enough oxygen to support plant growth.
Plants cannot live in anoxic soil environments as The gaps in anoxic soil are flooded with water, which prevents oxygen from reaching the plants.
However, wetland plants can grow in anoxic soils as they have adapted over time.
Let us discuss what anoxic soil is, whether plants can live in anoxic soil amongst other questions.
What Is Anoxic Soil?
The term ‘anoxic’ refers to situations devoid of molecular oxygen.
Normally, soil contains pockets of space between the grains of solid material that contain oxygen.
The gaps in anoxic soil are filled with water, which prevents oxygen from reaching the plants.
Anaerobic or anoxic soil conditions are most frequently induced by excessively damp soil or the prevalence of root-rotting microorganisms.
When water is unable to seep from the soil, new oxygen cannot be drawn in.
As a result, the soil’s biological activities deteriorate, organic matter decomposes, and tree roots consume all available oxygen.
The most prevalent sort of anoxic environment is a body of water. However, wetlands plants have adapted to anoxic soils and obtain oxygen from the air via their stems.
Anoxic soil can be caused by nature and can also be man-made.
It is difficult to prevent soil saturation with water during exceptionally wet seasons, which might result in anoxic soil.
Additionally, farmers might contribute to it during the dry season by overwatering the soil.
The most effective strategy to address this issue is to implement an effective irrigation system.
Here is an article I wrote on how to loosen compacted soil
Can Plants Live In Anoxic Soil?
Except they are aquatic or wetland plants, plants cannot survive in anoxic soil conditions.
While aquatic plants may endure anoxic soil, optimal plant growth requires oxygen. Without oxygen, the roots of plants will cease to grow and eventually die.
After an extended duration, the stomata begin to close, significantly reducing photosynthesis. These conditions would eventually result in the plant’s death.
If your soil is anoxic, it is better to grow wetlands plants that are tolerant of the dirt.
Wetland plants have learnt to survive in anoxic soils.
These plants adapt by obtaining oxygen via their stems rather than their roots, like normal plants do.
Why Can’t Plants Live In Anoxic Soil?
Plants can’t survive in anoxic soil because they require oxygen to grow and like we have mentioned above, anoxic soil does not have adequate oxygen for the plants to survive and grow.
Additionally, the absence of oxygen in such conditions has an effect on the aerobic respiration of plant roots and thus on the availability of plant nutrients.
Plant cells, like animal cells, undergo cellular respiration, which requires oxygen.
While the deeper sediments are often anoxic, there is normally a thin layer of oxidized soil at the soil water interface.
Without oxygen, plants cannot generate the energy required for survival, as oxygen is the final electron acceptor in oxidative phosphorylation.
In anoxic soil, plants will not survive long as they will develop anoxia or hypoxia stress. Anoxia stress is total oxygen-depletion while hypoxia is partial oxygen-depletion.
In either case, the lower the level of oxygen available to the plant roots, the more severe the harm to the plant.
Can Plant Roots Survive In Anoxic Soil?
Except they are wetland plants like rice or pea, plant roots cannot survive in anoxic soil as they require oxygen to grow.
Soil air spaces can become saturated with water as a result of poor environmental conditions such as flooding or water logging.
Plants growing in this sort of conditions may suffer from oxygen deprivation. This is due to oxygen’s low solubility and diffusion rate in water.
In anoxic soil, plant cells generate ATP only by anaerobic glycolysis, a method that produces less ATP and glucose.
The results are often higher in aerobic soil conditions.
Due to the fact that each molecule of glucose produces less than one-tenth of the ATP produced by oxidative phosphorylation during anoxia, the energy requirements of plant tissues cannot be supplied solely through glycolysis.
The resulting rapid decline in cellular ATP levels results in a slowing and eventually cessation of ion pump action.
As a result, ion homeostasis is disrupted, and ions begin to run down their electrochemical potential gradients.
As such the plants are unable to grow and might end up dying as their roots do not get enough oxygen.
Also check out this article I wrote on how to dispose old potting soil
How Do Plants Adapt To Waterlogged Soil?
Anoxic soil conditions have adapted wetlands and aquatic plants. Adaptations to these conditions, on the other hand, have an energy cost.
Either the organism’s cells are less efficient or they must expend energy to protect cells from external stress.
Recent research indicates that plants can reduce their oxygen consumption in response to a lack of oxygen, thereby avoiding internal anoxia.
Anoxia-tolerant species can use two different strategies to compensate for the loss of energy production.
They have the ability to increase glycolytic flux, which is known as the Pasteur effect. They can also engage in metabolic depression to slow the rate at which ATP is consumed.
Some of the wetland plants that are able to survive anoxic soils include:
- Floating water fern
- Bald cypress
- South Florida slash pine
Why Do Plant Roots Need Oxygen?
Roots require oxygen to function.
Roots literally do a lot of ‘heavy lifting’ in a plant, pumping ions across membranes to pull in water, concentrate other nutrients that the plant requires for survival and growth, and push the plant enough for all the nutrients to make it up into the leaves.
These processes necessitate the use of energy, which necessitates the use of oxygen.
When plant roots do not get enough oxygen, such as when they are overwatered, the roots themselves are damaged, which harms the plant as a whole.
However, there are exceptions, and some plants have adapted to damp conditions and have better methods for promoting oxygen diffusion.
This includes expanding the amount of air space in the roots, where oxygen diffuses faster than in aqueous media.
Other plants can survive temporary hypoxia by fermenting in their roots.
The conditions in which a plant exists is essential for its growth and survival.
Biology has taught us that plants require oxygen for proper development.
However, there are different soil types and conditions and anoxic soil is just one of them.
Anoxic soil is a type of soil that is oxygen deprived as water has flooded its chambers and occupies where there should be oxygen.
Without the oxygen, the plants will experience anoxia and die in due time.
Despite this, some plants have become adapted to the anoxic condition and have different adaptations for survival.
Wetland or aquatic plants are the major kind of plants that can be found thriving in anoxic soil conditions.