In recent decades, numerous studies about soil microbes have revealed their complex functional mechanisms in and around plant root systems, as well as their positive and at times negative influences on soil and plants. Thanks to the effort of many researchers in the relatively new field of pseudo-fertilizers, professionals and home gardeners alike have come to recognize the potential of products based on soil microbes as alternatives to conventional fertilizers. Mycorrhizal fungi, in particular, have been singled out for their potency amongst other soil microbes, resulting in their wide penetration of the market. Now everywhere you go, you can easily find a commercial mycorrhizal product without breaking a sweat.
But what, exactly, are mycorrhizal fungi? Essentially, they are a type of soil fungi that enter into a symbiotic relationship with the roots of most plants, forming a dense network of fungal hyphae around the plant’s root system. This relationship is beneficial to both the plant and the fungi; while the plant receives increased access to water and soil nutrients, particularly phosphorus, from the fungus’s extended root system (hyphae), the fungus obtains carbohydrates from the plant. There are two main types of mycorrhizal fungi: endomycorrhizal fungi and ectomycorrhizal fungi, which differ in their morphology as well. Mycorrhizal fungi contribute significantly to the plant growth soil fertility, and are thus an essential part of most ecosystems.
Arbuscular mycorrhizal fungi, or AMF, are a type of endomycorrhizal fungi that form symbiotic relationships with the roots of most higher plants. AMF are characterized by their branched, tree-like hyphae (known as arbuscules), which penetrate the plant’s root cells and extend out into the surrounding soil. The primary benefit that AMF confer to their host plants is increased access to phosphorus for root growth and other essential soil nutrients; in return, the plant provides carbohydrates to the fungus. Plants will absorb greater amounts of critical plant nutrients, become more resilient to drought stress, and will speed up growth of fine root hairs after they've been inoculated with this symbiotic fungi.
Ectomycorrhizal fungi, or EMF, are a type of mycorrhizal fungus that form symbiotic relationships with woody plants. Ectomycorrhizal fungi are characterized by their thick, sheath-like hyphae, which envelop the plant’s root cells and extend out into the surrounding soil. The primary benefit that Ectomycorrhizal fungi confer to their host plant roots is increased access to water and nutrient uptake; in return, the plant provides carbohydrates to the fungus.
The ericoid mycorrhiza is a type of mycorrhizal fungus that forms a mycorrhizal symbiosis with the plant family Ericaceae*. This type of mycorrhiza is characterized by its dense network of hyphae, which envelop the plant’s root cells and extend out into the surrounding soil. Ericoid Mycorrhiza is found in acidic soils with a low concentration of organic matter. Ericoid Mycorrhizae also can help reduce drought stress of host plants.
The orchid mycorrhiza form mycorrhizal relationships between members of the plant family Orchidaceae and the fungi. This type of mycorrhiza is found in a variety of habitats, including tropical rainforests, temperate forests, and grasslands.
While other symbiotic fungi are found in a variety of habitats, orchid mycorrhizal fungi are most commonly found in soils with a high concentration of organic matter, such as forest soils.
Mycorrhizal fungi are found in nearly all terrestrial ecosystems around the world, from tropical rainforests to arctic tundras. They play an important role in mediating plant-soil interactions and cycling nutrients within ecosystems. In agricultural systems, mycorrhizal fungi have been shown to improve plant growth, crop productivity and soil health.
Mycorrhizal fungi play a variety of roles in the soil environment, including breaking down organic matter, improving soil structure, and increasing plant productivity. One of the most important functions of mycorrhizal fungi is their ability to improve plant nutrient uptake. In addition to improving plant nutrient uptake, mycorrhizal fungi have specific roles and functions that can vary according to the type of mycorrhizal fungi.
Arbuscular Mycorrhizal Fungi form a symbiotic relationship with the host plant's root system by releasing enzymes that break down the cell wall in the plant roots. Once endomycorrhizal fungi penetrate the plant cell, they establish a symbiotic relationship. The hyphae of the Arbuscular Mycorrhizal Fungi extend into the cortical cells of the plant roots, where they form a network called the Hartig net. The vesicles of the Arbuscular Mycorrhizal Fungi store nutrients that are essential for plant growth. Inoculation by endomycorrhizal fungi has been shown to improve plant nutrient uptake and enhance plant growth.
(Credit to: Subodh Kumar Maiti, Dipita Ghosh, in Climate Change and Soil Interactions, 2020)
Ecto Mycorrhizae form symbiotic relationships with most woody and higher trees, providing their hosts with soil nutrients and water in exchange for plant carbon. This fungus family helps plants endure harsh conditions by maintaining their vitality and development. Ectomycorrhizal hyphae are crucial in the soil ecosystem's fungal network.
The importance of Mycorrhizal fungi in agriculture is becoming increasingly more apparent due to their ability to improve plant productivity, plant health and soil health. Furthermore, mycorrhizal fungi can help to reduce the need for chemical fertilizers and pesticides, making agriculture more sustainable, at a time when arable land is becoming more scarce.
Now, we've already established that there are many different types and classes of mycorrhizae. The answer to this question will focus primarily on Endomycorrhizal Fungi (Arbuscular Mycorrhizal Fungi, aka AMF), since this type of mycorrhizal fungi holds more weight in agriculture and gardening and is more heavily and widely used.
According to one of the leading manufacturers of mycorrhizal products, "the key benefits among many others that mycorrhizal fungi provide to professional growers are: root system enhancement of host plant with the help of fungal hyphae, improved nutrient efficiency, and increased water absorption & utilization, which leads to the exponential plant growth." True to its description, most commercial brands market their mycorrhizal products as ‘root boosters’ and ‘growth promoters’, often paired with photos of abnormally large roots balls of plants. Thanks to years of repeated marketing efforts of these brands, almost everyone who buys mycorrhizal products have come to hold high expectations- ones that anticipate miraculous results in plant/crop/grass growth and yields. Fortunately for these buyers, mycorrhizal fungi have proved themselves to be up to the task, showing time and again their success in boosting plant growth and yields, to the point where it’s no longer a question whether they are effective or not.
A testament to their effectiveness, mycorrhizal products have been produced and marketed by a variety of companies. However, because of the complexity of the subject and the intricacies of microbiology, most customers find it difficult to decipher the labels on these goods accurately to find one that fits their needs. Here are some tips and explanations that can help you decipher these labels.
The term ‘strain’ in microbiology refers to a particular microorganism that has been isolated from another population and is different enough to be classified as its own entity. For example, Glomus Intraradices, Glomus mosseae, Glomus aggregatum, Glomus etunicatum are a few common strains of endomycorrhizal fungi.
Penicalta et al. (2018) reported that there are over 7000 different identified species of mycorrhizal fungi, spread across several hundred genera and families. Of these, only about 150 to 200 species have been studied in detail thus far. This number is still relatively small compared to the total number of described plant species (~390,000), which highlights the importance of mycorrhizal fungi in plant development.
When using mycorrhizal products, it is essential to take into account the number of strains present in the product. A high number of strains usually indicates a higher quality product. However, this does not necessarily mean that products with fewer strains are automatically inferior. In many cases, products with fewer strains can be just as effective as those with more strains, depending on the specific formulation of the product and the needs of the plant.
For example, if a product is being used to inoculate a soil that has never been planted in before, it would be beneficial to use a product with a large number of different strains in order to ensure that all the necessary fungi are present. On the other hand, if the goal is to inoculate a soil that has already been planted in, then using a product with fewer strains may be just as effective.
This is because the mycorrhizal fungi in the soil have already had a chance to establish themselves and are likely to be more resistant to changes in the environment. In this case, using a product with fewer strains may be just as effective.
However, the conventional wisdom is that a higher number of strains is preferable, with the product's freshness taking precedence.
When looking at mycorrhizal products, you will often see the terms ‘spores’ and ‘propagules’. These two terms refer to the different life stages of mycorrhizal fungi.
Spores are typically the dormant stage of the fungus and are resistant to harsh conditions. They can remain dormant for long periods of time until the conditions are right for them to germinate.
Propagules, on the other hand, are the root fragments containing mycorrhizal spores, hyphae, vesicles that can influence fungal propagation and establishment of symbiosis with plant roots. Propagules are mentioned most commonly in context of mycorrhizal fungi, particularly endo-mycorrhizae that find refuge in root cells. Rhizobacteria and Trichoderma fungi, unlike mycorrhizae, reside in the root zone and do not require root fragments. As a result, non-mycorrhizal products will not contain propagules.
It is important to note that both spores and propagules are viable forms of mycorrhizal fungi and can be used to inoculate soil. However, propagules are generally considered to be more effective because they have a higher success rate in colonizing plant roots.This is due to the fact that they already contain the necessary mycorrhizal spores and have a higher chance of germinating. Moreover, propagules are less likely to be damaged by environmental conditions such as heat or cold.
When choosing a mycorrhizal product, it is important to consider the number of strains present, as well as whether the product contains spores or propagules. A high number of strains is usually indicative of a higher quality product, but this is not always the case. Propagules are generally considered to be more effective than spores, but both can be used to inoculate soil.
(Credit to: mycorrhizae.com/mycorrhizal-spore-vs-propagule-an-attempt-to-clarify)
When it comes to packaging and storing mycorrhizal fungi, the most essential thing is to keep them in good shape. The best method to ensure this is to acquire mycorrhizal components from reliable manufacturers. From a consumer standpoint, it’s also important to pay attention to the packaging and storage instructions on the label, as different products may have different requirements. For example, some products may require refrigeration, while others may need to be kept in a cool, dark place. When it comes to storage, mycorrhizal fungi can be stored in a dry location for up to two years. However, it’s important to keep in mind that the longer they are stored, the less effective they will be.
Mycorrhizal fungi are most commonly applied to the roots of plants, either through direct contact or soil drenching. The most common means of application is direct contact, which is usually carried out with a powder or granular mycorrhizal inoculant. To allow plant roots to touch the fungi directly, the mycorrhizal powder or granules are dispersed throughout the soil at planting or transplanting. Another popular method of application is soil drenching, which may be done with either a fine powder or a liquid mycorrhizal product. For this method, the mycorrhizal product is mixed with water and applied to the soil around the plant roots.
It’s important to note that mycorrhizal fungi need to be applied when the plant roots are actively growing in order for them to be most effective. This typically occurs during the spring and summer months.
As cultivators of soil microbes, we, at Microbial Applications, Inc. also understand the important role that mycorrhizal fungi will continue to play and expand in the upcoming agriculture and gardening industries. We also believe that it is our role and responsibility to deliver the true nature and potential of this miraculous fungi, beyond the pervading marketing messages and slogans currently dominating the market.
In order to fully understand the true nature, potential, and capacity of mycorrhizal fungi, we need to dig further into what other functions mycorrhizal fungi might serve, beyond the commonly marketed traits, much of which has been thoroughly covered above.
First, plants have two ways of achieving nutrient uptake- direct and indirect. Necessary nutrients are partially absorbed directly from the soil by plant roots through diffusion, while the rest are indirectly fulfilled by Arbuscular Mycorrhizal Fungi. "How?", you might ask. Once inoculated to a host plant, Arbuscular Mycorrhizal Fungi penetrate the cortical cells of roots and build a symbiotic relationship with the plant. Plants provide Arbuscular Mycorrhizal Fungi with sugar produced through photosynthesis, and in return, Arbuscular Mycorrhizal Fungi provide the host plants with essential nutrients in soil via fungal hyphae.
Next, roots can only absorb nutrients in limited areas of the root zone, whereas the finer and thinner structure of fungal hyphae have better access to soil pores and can explore larger soil volumes, resulting in a more efficient and effective structure for mining mineral nutrients including one key nutrient- phosphate. This is a mechanism already widely known to the public, and this is the very mechanism which has made Arbuscular Mycorrhizal Fungi stand out among other microbes as an alternative to traditional fertilizers. However, the hyper-focus on this mechanism alone fails to take into account the full extent of what mycorrhizal fungi are capable of.
This brings us to our next point: most soils, in their natural state, lack phosphorus. This is due to the fact that phosphorous is fixed as insoluble iron and aluminum phosphates in acidic soils (particularly in soil with a pH lower than 5.0) or as calcium phosphates in alkaline soils (with a pH above 7.0). This is where other soil microbes such as pseudomonas, bacillus, aspergillus, Trichoderma, and penicillium play an important role in solubilizing ‘fixed phosphate’ into accessible phosphate in the form of H2PO4-(dihydrogenphosphate) or HPO42-(hydrogenphosphate). They do this by producing organic acids- gluconic, citric, oxalic, lactic, isovaleric, succinic, glycolic, acetic, etc., through chelation, and through mineralization via alkaline/acid phosphatases. Arbuscular Mycorrhizal Fungi then absorb and transport the phosphate made accessible back to the roots for the nutrient consumption of the plant.
Phosphate solubilization, or P solubilization capacity of microbes varies highly depending on nutritional conditions, already-existing microbial community in the soil, soil pH, and plant type, among many other factors. In theory, mycorrhizal fungi are not much more than transporters of nutrients. Furthermore, the nutrients in soil will not be plentifully available unless other soil bacteria and fungi work to produce and make them available. In reality, however, mycorrhizae alone can also be effective, because most soils already contain microbes in their soil ecosystem, and because most people apply additional nutrient supplements when applying mycorrhizal fungi.
Nevertheless, all things considered, you have a higher chance of getting better outcomes when combining mycorrhizal fungi with other beneficial soil bacteria and fungi. When combined, different species of soil microbes interact with each other on a functional as well as a physiological level. One example of how this interaction manifests can be observed in the influence of Arbuscular Mycorrhizal Fungi on the colonization of PSB (phosphate solubilizing bacteria). Another example is how Bacillus and Trichoderma come together to contribute to Arbuscular Mycorrhizal Fungi propagation.
At this point, you may be wondering how this information all comes together and applies to Mikro-Myco.
There are so many mycorrhizal products to choose from- some with only mycorrhizal fungi, and others with varying inclusions of non-mycorrhizae soil bacteria and fungi. Even with a large selection of choices, rarely have we seen brands combining considerable amounts of rhizobacteria and beneficial fungi with mycorrhizae. Yet, as mentioned above, studies have shown that better outcomes result when combining mycorrhizal fungi with other beneficial soil bacteria and fungi. This was the logic behind the creation of our first product- Mikrobs, which contains significant amounts of AMF, Trichoderma, AND Bacillus, along with organic nutrients for microbes and plants. In Mikrobs, however, the leading player of the blend is PGPR (plant growth promoting rhizobacteria). For this reason, we decided to launch a different formula that focuses on mycorrhizal functions: Mikro-Myco. A primarily mycorrhizal product, it is comprised of an ideal combination of Endo Mycorrhizae (260 cfu/g), Ecto Mycorrhizae (218,000 cfu/g), Trichoderma (750,000 cfu/g), and Bacillus (400,000,000 cfu/g).
A infographic explaining some of the functions & processes of Mikro-Myco:
Mikro-Myco is focused on enhancing the functions of mycorrhizal fungi, combining different microbes in a formulation that best amplifies and strengthens all its possible roles as outlined in our in-depth investigation of mycorrhizal fungi above. We know all that mycorrhizal fungi are capable of, and that their functions and benefits are well beyond what they're currently pigeonholed into serving. Mikro-Myco is a reflection of our expertise and desire to translate and transfer all this knowledge directly into tangible results visible in your gardens and fields.
Ericaceae: A family of flowering plants that includes blueberries, cranberries, and huckleberries.
Fungal Hyphae: So-called mycorrhizal roots. These mycorrhizal roots are the long, thread-like structures that make up the bodies of fungi.
Mycelium: The vegetative body of a fungus, which is composed of a network of mycorrhizal hyphae.
Hyphal Tips: The tips of the mycorrhizal hyphae, where growth occurs.
Arbuscules: Tiny, tree-like structures that form inside plant cells.
Vesicles: Small, round sacs that store nutrients.
Bacillus: A genus of bacteria that includes many soil-dwelling species. They are know to break down soil organic matter such as plant tissues, animal residue, cells and tissues of soil microbes and substances that soil microbes synthesize. These soil microbes play an important role in nutrient cycling in the soil by converting fixed nutrients to readily available forms to plants.
Trichoderma: A genus of fungi that includes many species that are important in agriculture. Not only Trichoderma solubilize soil organic matter, but also they encourage plants to grow fine roots. Trichoderma fungi that are present in adequate amounts in the soil help plants to be more resilient to environmental stress, such as salt stress, drought stress, metal toxicity, and so on.
Nonmycorrhizal Plants: Plants that do not form symbiotic relationships with mycorrhizal fungi. Some Brassicaceae, Aizoaceae, Capparaceae are the examples of nonmycorrhizal plants.
Comments will be approved before showing up.