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The important connection between roots and fungi

Underground Relationships

Modern AgricultureApril 25, 2018

Exploring the Underground Network of Plants

Plants are a lot like people–they need relationships to thrive. At first glance, it might appear that they work alone, using the magic of photosynthesis to convert sunlight into life. Upon further investigation, however, it becomes clear that they rely on their surroundings a great deal.

Consider the various relationships that involve plants. They have a relationship with the air around them, taking in sunlight and carbon dioxide and returning water and oxygen. They also have a relationship with the soil beneath them, which provides a network of support that delivers the water and nutrients necessary for plants to grow and thrive.

The Roots of Crop Science

For many people, the word network conveys a sense of connectivity, improved efficiency, and resilience against unwelcome events. For farmers, who are interested in all three of those outcomes, one of the most important networks is one they can’t even see.

This network is called mycorrhiza (MY-co-RI-za). It refers to the symbiotic relationship root systems develop with soil fungi. The name comes from the combination of mycology, the study of fungi, and rhizosphere, the soil ecosystem in which plant roots are found.

Almost all species of green plants benefit from establishing this root-fungi relationship, and soils without active mycorrhiza are often considered degraded. Their symbiotic relationship plays out like a two-way distribution network. The plant above ground transports the products (carbon-based organic compounds) of photosynthesis down through its roots to the fungi, and the fungi help the roots collect water and soil nutrients which are then distributed back up to the plant.

[unex_ce_article_half_width_text_and_image layer-name="Mycorrhiza Image Text" mobile_image="2246" mobile_image_filename="Roots-1.jpg" caption="" image_location="image-right" id="content_442n201ww" post_id="2237"]

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Almost all species of green plants benefit from establishing this root-fungi relationship.

[unex_ce_article_full_width_photo layer-name="full-width image #1" img="3033" image-filename="Full-Width_Subway-Map-1-1.jpg" id="content_1hvcdmvqq" post_id="2237"] <h3><span style="color:#FFFFFF;">Almost all species of green plants benefit from establishing this root-fungi relationship.</span></h3> [/ce_article_full_width_photo]

Providing Benefits for Plants and the Planet

This underground network helps facilitate as many as three beneficial outcomes. It sequesters carbon underground, which is a positive for the environment. It also amplifies the ability of root structures to collect water and nutrients from the soil. And it protects plants from disease.

Carbon Sequestration

Because it contains no above-ground component, the fungal network is completely dependent on the host plant for access to the carbon acquired through photosynthesis. The above-ground plant sends carbon compounds underground, where they can be used by the fungi. Researchers have recently learned that mycorrhiza also plays a prominent role in storage of carbon within the soil. This benefits the environment, as it reduces the amount of carbon in the atmosphere.

[unex_ce_indent_outdent_images layer-name="Carbon Sequestration with image" headline_markup="" img="3034" image-filename="Indent_Outdent-Competitive-Exclusion-2.jpg" image_caption="Image Caption Text" image_caption_color="white" id="content_b2uzxz0h3" post_id="2237"] <h3 style="word-wrap: normal">Carbon Sequestration</h3><p><span style="color:#5f5e65;">Because it contains no above-ground component, the fungal network is completely dependent on the host plant for access to the carbon acquired through photosynthesis. The above-ground plant sends carbon compounds underground, where they can be used by the fungi. Researchers have recently learned that mycorrhiza also plays a prominent role in storage of carbon within the soil. This benefits the environment, as it reduces the amount of carbon in the atmosphere.</span></p> [/ce_indent_outdent_images]

Carbon sequestration begins in the chloroplasts of all green plants, which are the site for photosynthesis.

More Water and Nutrients

The fungi return the favor by spreading out within the soil, scavenging for vital nutrients and moisture, then delivering them back to the host plant. This amplifies the ability of the root system to sustain the plant above ground, in two primary ways. First, it acts as an extension of root systems underground. Second, it plays a key role with respect to phosphorous, one of the three primary macronutrients all plants need (the others are nitrogen and potassium). Phosphorous is often bound, or locked, in the soil, making it difficult for roots to access. Mycorrhiza can help unlock it, facilitating its use by the plant.

[unex_ce_article_half_width_text_and_image layer-name="More Water and Nutrients_image on right" mobile_image="3035" mobile_image_filename="More-Water-and-Nutrient-SIde-image-1-1.jpg" caption="" image_location="image-right" id="content_4nd0zos2y" post_id="2237"] <h3>More Water and Nutrients</h3><p>The fungi return the favor by spreading out within the soil, scavenging for vital nutrients and moisture, then delivering them back to the host plant. This amplifies the ability of the root system to sustain the plant above ground, in two primary ways. First, it acts as an extension of root systems underground. Second, it plays a key role with respect to phosphorous, one of the <a href="https://modernag.org/soil-health/nutrient-management-tools/">three primary macronutrients</a> all plants need (the others are nitrogen and potassium). Phosphorous is often bound, or locked, in the soil, making it difficult for roots to access. Mycorrhiza can help unlock it, facilitating its use by the plant.</p> [/ce_article_half_width_text_and_image]

Competitive Exclusion

Another key benefit of this relationship is disease suppression. By physically occupying space on and around the roots, mycorrhiza blocks pathogens that could potentially cause an outbreak of disease. This is known as competitive exclusion.

Seed treatments help promote the growth of beneficial soil microbes.

[unex_ce_article_full_width_photo layer-name="Seed Treatment" img="3036" image-filename="Full-Width_IMAGE-copy-1.jpg" id="content_e50z12h25" post_id="2237"] <h3><span style="color:#FFFFFF;">Seed treatments help promote the growth of beneficial soil microbes.</span></h3> [/ce_article_full_width_photo]

How is Modern Agriculture Supporting This Network?

Farmers and agricultural researchers have known about the important role played by mycorrhiza since the mid-1980s. As a result, a wide variety of products exist to enhance its impact. The most common tools being used today are microbial seed treatments. They generally act as inoculants, encouraging the development of these root-fungi networks.

These seed-applied products are most commonly used to support robust development of seedlings after planting, and to prevent fungal diseases from compromising young plants. Several of them involve the use of microbes that help promote beneficial bacteria in the soil.

Because seed-applied products can enhance efficiency, they can play a major part in modern agricultural sustainability efforts. Crops with robust mycorrhizal networks tend to be healthier and better at growing strong and defending themselves. As a result, they require fewer resources to grow, which is good for farmers and the environment.

[unex_ce_indent_outdent_images layer-name="Seed Applied Sol Image/Text" headline_markup="" img="3037" image-filename="Indent_Outdent-How-is-Modern-Agriculture-1.jpg" image_caption="Image Caption Text" image_caption_color="white" id="content_w2lj1bvnl" post_id="2237"] <p><span style="color:#5f5e65;">Because seed-applied products can enhance efficiency, they can play a major part in modern agricultural <a href="https://modernag.org/soil-health/role-of-microbials-nutrient-management/">sustainability efforts</a>. Crops with robust mycorrhizal networks tend to be healthier and better at growing strong and defending themselves. As a result, they require fewer resources to grow, which is good for farmers and the environment. </span></p> [/ce_indent_outdent_images]