Why Do Plants Need Carbon Dioxide And How It Affects Plant Growth?

As a significant greenhouse gas, carbon dioxide has a negative reputation for contributing to climatic changes, acid rain, and other environmental problems. Its steady rise in the atmosphere also impacts health, causing breathing difficulties and headaches. All the negatives aside, you cannot overlook the fact that the same gas sustains plant life!

This is because, without carbon dioxide around us, plants won’t exist – it’s as simple as that! And if plants stop existing, the apocalypse will follow. After all, the world’s green inhabitants sit at the bottom of the food chain, governing the existence of all other living things!

But why do plants need carbon dioxide, how important is it, and where does it come from? Are your plants getting enough of it from their surroundings? Let’s take a more in-depth look at the role of carbon dioxide in plants.

© jro-grafik – stock.adobe.com

Where Does Carbon Dioxide Come From?

Where do plants get their share of carbon dioxide from? What are the sources of carbon dioxide? You may already know that carbon dioxide is naturally present in the atmosphere. Dry air contains 0.04% carbon dioxide.

Even though 0.04% is a small percentage, carbon dioxide is an integral part of the carbon cycle. The CO2 that plants use gets returned to the environment due to decomposition, respiration, and ocean discharge. Natural sources that use and release carbon in the atmosphere maintain a harmonious balance in carbon dioxide concentration in the air.

But, natural sources aren’t the only ones impacting its level. Human activities, notably the burning of fossil fuels and cement production, release unwanted carbon dioxide. Furthermore, excessive deforestation reduces the natural consumption of carbon dioxide by plants, which causes a rise in carbon dioxide in the environment. There’s a steady rise in the atmosphere’s carbon dioxide levels, increasing the greenhouse effect and global warming.

So as it turns out, the air has plenty of carbon dioxide for the plants to photosynthesize. They absorb carbon dioxide from the air to carry out photosynthesis. Later, we’ll also explain how the absorption is carried out and if an excess of carbon dioxide can boost production?

How Do Plants Take In Carbon Dioxide?

Humans and animals give out carbon dioxide as a byproduct of respiration. In contrast, plants take in carbon dioxide from the air around them. CO2 enters the plants through tiny holes called stomata.

These small pores are present throughout the plant structure, including leaves, flowers, branches, stems, and even roots. They’re typically located on the underside of the leaves to minimize water loss through the openings. Oxygen also gets released through the same portal.

Why Do Plants Need Carbon Dioxide?

You may already have guessed this one. So you understand that the plants take in CO2 through their tiny holes. But what do they do with it? How do they use it? Let’s find out the answer to: why do plants need carbon dioxide?

It’s simple. Plants need it to carry out photosynthesis to produce their food. Along with water and sunlight, carbon dioxide is one of the three essential inputs for the process of photosynthesis. The energy from the sun catalyzes the reaction between carbon dioxide and water to form glucose and water.

What Are The Stages Of Photosynthesis?

Looking into it a little deeper, photosynthesis is carried out in two stages: light-dependant reactions and light-independent reactions. In light-dependant reactions, as in the first stage, light energy from the sun is converted to chemical energy. This chemical energy is used in ATP and NADPH molecules to drive the second stage of light-independent reactions.

Carbon dioxide shows its role in the second stage of photosynthesis – light-independent reactions. In these reactions, also called the Calvin cycle, chemical energy created during the first stage of photosynthesis creates carbohydrates from carbon dioxide molecules.

What’s The Output?

As the output of photosynthesis, plants create C6H12O6 and oxygen. Oxygen is released through the same stomatal openings that absorb carbon dioxide, while the glucose molecule is utilized in plant growth.

How Does A Plant Use Its Food?

Though you have some idea about why plants need carbon dioxide, the gas’s role isn’t over yet. The glucose molecule created during photosynthesis is used to carry out respiration in the plant’s leaves, stems, and roots. It breaks the sugar molecule to generate energy for different metabolic processes, releasing carbon dioxide and water.

Generally, since CO2 availability is high in the surroundings, plants create more food than they need to sustain their processes. In some, this extra food is in fruits or vegetables, consumed by humans or animals. But some plants also keep it in their leaves.

In short, the plants’ carbon dioxide helps create food for the development of plants and the sustenance of animals and humans.

Can An Increase In Carbon Dioxide Levels Boost Plant Growth?

So it’s inevitable – plants need carbon dioxide to create food and sustain life. Now you may be wondering if an excessive amount of carbon dioxide in the environment can be a good thing. After all, more carbon dioxide in the surroundings should mean more photosynthesis and better growth. Will pumping supplemental CO2 enhance plant growth? It depends; the answer isn’t as straightforward as one might think.
Let’s see how an increase in carbon dioxide levels can impact crops:

Is Extra CO2 Good For Plants?

Studies that measure the impact of CO2 concentrations on plants show that results vary with the species. Some plants can enjoy from an excess of carbon dioxide, but some show loss. A greenhouse study back in 1979 revealed that doubling the carbon dioxide concentrations in the surrounding air can double the yield of cotton plants.

Studies have been carried out in greenhouses and open fields to observe the effects of pumping more of this gas into the surrounding air. A 2005 study reveals an average increase of 17% on crop yield at 475 to 600 parts per million carbon dioxide. Legumes generally show a more significant positive response than other varieties.

But Can Too Much CO2 Hurt Plant Growth?

When used in excess, even good things can lay profound side effects. Carbon dioxide, for one, is a greenhouse gas. Its incorrect or excessive use can impact the environment and plants negatively. High levels of CO2 in greenhouses can cause necrosis in tomato and cucumber plants. Flowers can also suffer, often resulting in malformed flowers.

Some researchers believe that while an increase in carbon dioxide levels can enhance yield, it can lower the nutritional quality of fruits and vegetables by raising carbohydrate levels and reduce proteins, zinc, iron, and other vital nutrients.

The current rise in carbon dioxide in the atmosphere through human activities isn’t all good for plants. The increased levels of this greenhouse gas affect the global climate, temperatures, and rainfall patterns. While CO2 promotes photosynthesis, climatic changes will also impact plant growth, unfortunately, sometimes negatively.

What Is Meant By Organic Carbon? – “What? Is There Carbon In Soil?”

Air isn’t the only source of carbon for the plants. Plant roots absorb organic carbon from the decomposing organic matter in the soil. In this form, Carbon ensures healthy plant growth and improves soil structure over time.

Healthy soil will, in the long run, promote the development and productivity of crops. It also encourages microbial activities and lowers the need for synthetic fertilizers.

Frequent organic matter applications to the ground as mulch will ensure that the carbon supply is continuously replenished to the soil. The plants use this carbon while some go into the environment as CO2, part of the carbon cycle.

Final Words

So why do plants need carbon dioxide? By now, you’ll likely be well aware of the importance of carbon dioxide to plants. In short, without carbon dioxide, plants won’t be able to carry out photosynthesis.

Without photosynthesis, we won’t be seeing those green, healthy branches with clusters of red tomatoes or berries hanging from them. All plants are dependant on CO2 for their survival. In turn, we are dependent on the plants as our primary food source.

So, we want carbon dioxide in our environment, but not too much that it starts melting those beautiful ice caps of the north pole and raising the temperatures around us.

Leave a Comment