Introduction to Mycorrhizae

Brief Overview of Mycorrhizae

Mycorrhizae are vital symbiotic relationships between soil mycorrhizal fungi and plant roots, enhancing nutrient uptake and plant health. These beneficial fungi, including arbuscular mycorrhizal and ectomycorrhizal fungi, form extensive networks through fungal hyphae that connect individual plants, facilitating the exchange of essential nutrients like phosphorus and nitrogen.

By improving plant nutrition and increasing resistance to root diseases, mycorrhizal associations play a crucial role in the growth of many plants, including woody plants and vegetable crops, while reducing the need for chemical fertilizers.

Importance in Ecosystems and Gardening

Mycorrhizal fungi play a crucial role in ecosystems and gardening by forming symbiotic relationships with plant roots, enhancing plant growth and health. These beneficial fungi, including arbuscular mycorrhizal and ectomycorrhizal fungi, improve nutrient uptake from the soil, allowing host plants to obtain essential nutrients even in adverse conditions.

By fostering these mycorrhizal associations, gardeners can enhance crop production, promote disease resistance, and reduce reliance on chemical fertilizers, creating a healthier environment for diverse plant species.

What is mycorrhizae?

Myco-what? mycorrhizae fungi, pronounced my-coh-RYE-zay, scientists and gardeners both have been learning more in recent years about these mycorrhizal fungi and how they benefit the garden and ecosystem. But just what is it, and why do your plants need it?

Types of Mycorrhizae

Endomycorrhizae (Arbuscular Mycorrhizae)

Endomycorrhizae, specifically arbuscular mycorrhizal fungi, form intimate symbiotic relationships with the roots of many vascular plants, enhancing their ability to absorb plant nutrients from the soil. These beneficial fungi penetrate the root cells, creating a vast network of fungal hyphae that connects individual plants and aids in nutrient exchange, particularly in accessing essential minerals and water.

Commonly found in garden plants, vegetable crops, and woody plants, these mycorrhizal associations not only promote plant growth and health but also increase disease resistance against soil-borne pathogens.

Ectomycorrhizae

Ectomycorrhizae are a type of mycorrhizal association formed primarily with the roots of woody plants, particularly trees like pines and oaks. These beneficial fungi envelop the root tips in a protective fungal sheath and extend fungal hyphae into the surrounding soil, enhancing nutrient uptake, especially of essential minerals.

By improving plant nutrition and health, ectomycorrhizal fungi play a vital role in the growth of many plant species, promoting resilience against plant pathogens and supporting overall ecosystem health.

Tiny plant helpers

Mycorrhizae, a term derived from the Greek words 'mykos', meaning fungus, and 'rhiza', meaning root, refer to a type of fungi that form symbiotic associations with plant root systems. This symbiotic relationship is widespread, encompassing approximately 95% of plant species worldwide, excluding certain families such as Brassicaceae, which includes vegetables like cabbage, broccoli, and radish.

The symbiosis between mycorrhizae and plant roots is primarily beneficial for nutrient acquisition. Plants provide the fungi with carbohydrates, products of photosynthesis, and in return, the mycorrhizae enhance the plant's access to soil nutrients, particularly those that are less mobile or in limited supply, such as phosphorus, nitrogen, and micronutrients. This mutualistic relationship is crucial for many plants, especially in nutrient-poor soils.

Mycorrhizae extend far beyond the root's physical reach by forming extensive networks known as mycelium. These networks increase the root's surface area for absorption, thereby facilitating greater uptake of water and nutrients. This mechanism is particularly advantageous in environments where these resources are scarce or sporadically available.

In leguminous plants, the role of mycorrhizae is even more pronounced due to their interaction with nitrogen-fixing bacteria. These bacteria, housed in root nodules, convert atmospheric nitrogen into forms usable by the plant. Mycorrhizae assist in this process by enhancing the overall nutrient and water uptake efficiency of the plant, thus supporting the energy-intensive nitrogen fixation process.

Furthermore, mycorrhizae contribute to soil health by improving soil structure. Their mycelial networks help in aggregating soil particles, which enhances soil porosity and aeration. This improvement in soil structure facilitates root growth and microbial activity, leading to a more dynamic and healthy soil ecosystem.

Mycorrhizae also play a role in plant health beyond nutrition. They can suppress soil-borne pathogens either by outcompeting them for resources or by inducing systemic resistance in the plant. This biocontrol aspect is crucial in sustainable agriculture, reducing the need for chemical fungicides and pesticides.

Additionally, mycorrhizal fungi can act as a bridge between different plants, creating a network through which nutrients and signals can be exchanged. This interconnected network, often referred to as the "wood wide web," allows plants to share resources and communicate, thereby enhancing the resilience of the plant community to environmental stresses.

Mycorrhizae and Soil Health

Impact on Soil Aggregation and Aeration

Mycorrhizae play a crucial role in enhancing soil health by promoting soil aggregation and aeration through their extensive networks of fungal hyphae. These beneficial fungi, including arbuscular mycorrhizal fungi and ectomycorrhizal fungi, form symbiotic relationships with plant roots, enabling host plants to obtain essential nutrients and mineral nutrients from the surrounding soil more efficiently.

This nutrient exchange not only boosts plant growth and health but also improves disease resistance against soil-borne organisms, ultimately benefiting a variety of plant species, including woody plants and vegetable crops.

Role in Microbial Activity

Mycorrhizae play a vital role in soil health by enhancing microbial activity through their intricate fungal networks. These soil mycorrhizal fungi, including arbuscular mycorrhizal fungi and ectomycorrhizal fungi, establish mycorrhizal associations with plant roots, allowing host plants to effectively obtain essential nutrients and improve plant nutrition.

This symbiotic relationship not only supports plant growth and health but also fosters a rich environment for beneficial microorganisms, increasing soil resilience against plant pathogens and adverse conditions.

Biocontrol of Pathogens

Mycorrhizae play a significant role in the biocontrol of pathogens by fostering beneficial fungi that enhance plant resilience against diseases. Soil mycorrhizal fungi, including arbuscular mycorrhizal fungi and ectomycorrhizal fungi, form mycorrhizal associations with plant roots, helping host plants obtain essential nutrients while also providing a barrier against harmful plant pathogens.

This symbiotic relationship not only promotes plant growth and health but also enhances disease resistance, making mycorrhizal plants more robust in the face of root diseases and soil-borne organisms.

Encouraging Mycorrhizal Growth

Best Practices for Soil Management

Encouraging mycorrhizal growth is essential for healthy soil management and can significantly enhance plant health. To foster beneficial fungi like arbuscular mycorrhizal fungi and ectomycorrhizal fungi, it's important to maintain organic matter in the soil and minimize the use of chemical fertilizers, which can disrupt mycorrhizal associations.

By promoting diverse plant species and ensuring a well-structured root system, gardeners and farmers can enhance the symbiotic relationships between mycorrhizal fungi and plant roots, leading to improved nutrient uptake and overall plant growth.

Techniques for Enhancing Mycorrhizae Populations

To enhance mycorrhizae populations, adopting specific techniques can significantly benefit soil health and plant growth. Incorporating organic matter into the soil encourages the proliferation of beneficial fungi, such as arbuscular mycorrhizal fungi and ectomycorrhizal fungi, which form essential mycorrhizal associations with plant roots.

Additionally, selecting diverse plant species that thrive in symbiotic relationships with mycorrhizal fungi can improve nutrient uptake and bolster disease resistance, creating a robust environment for mycorrhizal relationships to flourish.

Recommended Products for Inoculation

When looking to boost mycorrhizal growth, using recommended products for inoculation can make a significant impact on plant health. Look for mycorrhizal products containing a mix of soil mycorrhizal fungi, including arbuscular mycorrhizal fungi and ectomycorrhizal fungi, which enhance root systems and improve nutrient uptake.

These products typically include fungal spores and mycorrhizal fungi that help establish robust mycorrhizal symbiosis, allowing plants to obtain essential nutrients more effectively and fostering a thriving underground network that supports overall plant biology.

Cultivating Mycorrhizae in Your Garden

How to Use Mycorrhizal Inoculants

To cultivate mycorrhizae in your garden, using mycorrhizal inoculants can be a game changer for plant health. Start by selecting the right mycorrhizal products that contain a blend of soil mycorrhizal fungi, such as arbuscular mycorrhizal fungi and ectomycorrhizal fungi, which will enhance your host plants' ability to obtain nutrients from the soil.

When applying these inoculants, ensure they come into contact with the root system, allowing fungal spores and hyphae to penetrate root hairs and establish a robust mycorrhizal symbiosis that supports the entire fungal network, promoting plant growth and resilience.

Tips for Planting with Mycorrhizae

When planting with mycorrhizae, it's essential to incorporate mycorrhizal products directly into the planting hole to maximize the benefits of soil mycorrhizal fungi. Choose a suitable mycorrhizal inoculant that contains various fungal species, including arbuscular mycorrhizal fungi, to promote robust mycorrhizal symbiosis with your host plants.

Ensure that the fungal spores come into contact with the root hairs and the surrounding soil solution, allowing the hyphae to penetrate and establish an extensive network that enhances nutrient uptake and supports overall plant biology.

Endo or Ecto?

There are two kinds of mycorrhizae: endomycorrhizae and ectomycorrhizae. Both live partially within the roots of their host plants, and also spread fungal hyphae away from the plant roots into the soil. Arbuscular mycorrhizae or Endo (meaning “in”) mycorrhizae penetrate into the cells of the roots of plants with which it forms relationships. The fungal hyphae deliver nutrients directly into the plant cells. A wide range of plants can live symbiotically with endomycorrhizae including most vegetables, grasses, flowers, shrubs and fruit trees.

Ecto (“out”) mycorrhizae live in between the cells of roots forming a “net” through the root, and also coat the outside of the root. This mycelial network delivers nutrients to the outside of plant cells with which they are in direct contact, but the plant must absorb the nutrients into the cells itself. Ectomycorrhizae form relationships with only a few kinds of trees including oaks and conifers.

Improving your soil with fungi!

There are many species of mycorrhizae, which typically can form relationships with multiple species of trees, flowers and garden veggies. Scientists have even discovered that one mycorrhizal fungus can simultaneously inhabit the roots of two or more different species of plants, and this connection is so strong that the health of one plant directly affects the other.

Mycorrhizae is present in most soils, and it can be encouraged to grow and flourish by caring for your soil with mulching, cover cropping, adding organic matter, and by not making rapid changes to the soil nutrient levels or pH. Low or no-till farming and gardening is better for mycorrhizae than conventional tillage. To add more mycorrhizae to your soil, you can inoculate your garden with Chappy's Root Booster or Granular Root Growth Enhancer, or select potting soils or fertilizers with this ingredient.

Some mycorrhizae also produce edible “fruiting bodies”: growing your own morel mushrooms is a delicious way to help your garden at the same time! Check out the book Mycelium Running by Paul Stamets for in depth and practical information on these and other fungi.

Conclusion

In conclusion, mycorrhizae represent a vital aspect of soil health and plant growth, showcasing the remarkable symbiotic relationships between soil mycorrhizal fungi and plant roots. By enhancing nutrient uptake through extensive networks of fungal filaments, these beneficial fungi, including arbuscular mycorrhizal and ectomycorrhizal species, significantly improve plant biology and resilience.

As host plants access essential nutrients from the soil solution, they thrive, leading to healthier ecosystems where both land plants and tree roots flourish. By understanding and fostering mycorrhizal associations, gardeners can optimize their growing environments, enhancing plant nutrition and overall health while minimizing reliance on chemical fertilizers.

Embracing these natural processes is key to sustainable gardening and agriculture, making mycorrhizal fungi an invaluable ally in cultivating robust, thriving plants. To explore our Mycorrhizal Inoculants and Mycorrhizae Inoculants, visit Grow Organic.

FAQs About The Dirt on Mycorrhizae

• What are soil mycorrhizal fungi and why are they important?

  • Soil mycorrhizal fungi are beneficial organisms that form symbiotic relationships with land plants. These fungi connect with a plant’s root system, helping them obtain nutrients from the soil that would otherwise be inaccessible, like phosphorus and nitrogen. This mycorrhizal symbiosis plays a crucial role in improving soil health, plant growth, and the uptake of other nutrients essential for plant development.

• How do mycorrhizal fungi interact with plant roots?

  • Mycorrhizal fungi form close partnerships with plant roots by either surrounding the root system or penetrating the root cells. In arbuscular mycorrhizal symbiosis, the fungi's hyphae penetrate the root cells, creating a direct connection between the fungal network and the plant host. This allows for the exchange of plant nutrients and other essential elements in the soil solution.

• What is the difference between arbuscular mycorrhizae and ectomycorrhizal roots?

  • Arbuscular mycorrhizae are the most common form of mycorrhizal symbiosis and occur when the fungal filaments (or hyphae) penetrate the root cells of the host plant, directly facilitating the transfer of nutrients from the soil. In contrast, ectomycorrhizal roots are characterized by the formation of a fungal sheath around the root, without penetrating the plant's cell walls. These ectomycorrhizal fungi mainly associate with tree roots and form a vast extensive network in forest ecosystems.

• How do mycorrhizal fungi help plants obtain nutrients from the soil?

  • The fungus root (the mycorrhiza) works as an extension of the plant’s root system, increasing the surface area for nutrient absorption. The fungal filaments reach deep into the soil to access nutrients like phosphorus, nitrogen, and water, transferring these resources to the plant’s root hairs. This partnership allows plants to efficiently obtain major nutrients from the soil, especially in nutrient-poor environments.

• What role do fungal spores play in mycorrhizal symbiosis?

  • Fungal spores are the reproductive units of mycorrhizal fungi. When they germinate, they grow into hyphae that seek out plant roots to form a symbiotic relationship. These spores are critical in spreading the fungi to new environments and facilitating the establishment of new mycorrhizal products in agriculture and horticulture.

• Can mycorrhizal fungi communicate with plants?

  • Yes! Underground signals carried by mycorrhizal fungi can alert plants to various conditions in the soil. These signals help plants adjust their growth patterns and nutrient uptake accordingly. This communication system extends across an extensive network of fungal species, sometimes referred to as the "wood-wide web."

• Are there different fungal species involved in mycorrhizal relationships?

  • Absolutely! Several different species of mycorrhizal fungi exist, including arbuscular mycorrhizae (which associate with most land plants) and endomycorrhizal fungi, as well as ectomycorrhizal fungi, which primarily partner with trees. Each species has evolved to work with specific types of plants, helping them thrive in different environments.

• Do mycorrhizal fungi only help plants obtain nutrients, or do they provide other benefits?

  • In addition to helping plants obtain nutrients, mycorrhizal fungi improve soil structure, protect plants from pathogens, and increase resistance to environmental stresses like drought and heavy metals. Their extensive network also helps distribute water and other nutrients more efficiently within plant communities.

• What is the significance of the root epidermis in mycorrhizal symbiosis?

  • The root epidermis is the outermost layer of the root where the initial interaction between the fungi and the plant takes place. Mycorrhizal fungi colonize this layer before penetrating deeper into the root tissues (in the case of arbuscular mycorrhizae) or wrapping around the root (as in ectomycorrhizal roots), allowing the exchange of nutrients and signals between the fungal species and the plant host.

• Can I introduce mycorrhizal fungi into my garden?

  • Yes! Many mycorrhizal products are available for home gardeners. These products contain fungal spores that can be added to your growth media or directly to your soil. By incorporating these fungi, you can enhance your plants' ability to absorb nutrients from the soil, especially in nutrient-poor environments.

Additional Resources

1. "Mycorrhizae — Worth the Investment?" by Judy Kunz, Colorado Master Gardener, from Arapahoe County Extension. This article discusses the role of mycorrhizae in soil health and questions the effectiveness of commercial mycorrhizae additives in garden soils. It also advises on practices that can enhance or harm mycorrhizae populations in soil​.

2. "A Gardener's Primer to Mycorrhizae: Understanding How They Work and Learning How To Protect Them," a publication from the WSU Extension, which explains the symbiotic relationships between mycorrhizae and plant roots, and provides guidance on how gardeners can protect these beneficial fungi.

3. "Mycorrhizae: Nature's Gift to Plant Health" from the University of Missouri's Integrated Pest Management program. This article discusses different types of mycorrhizal relationships, the benefits they provide to plant growth, and the use of mycorrhizal supplements in agriculture.

4. "The Effects of Mycorrhizal Fungi Inoculum on Vegetables" by the Master Gardeners of San Mateo & San Francisco Counties. This study compares the yield and vigor of vegetables grown with and without mycorrhizal fungi plant inoculum, providing practical insights for home gardeners​.