Mycorrhiza is the symbiotic relationship between plants and fungi.
Myco = fungus
rhiza = root
This article originally appeared on Growers Network – you can find the original article here.
Mycorrhiza is the symbiotic relationship between plants and fungi. The earliest evidence found for this fascinating association of plants and fungi dates back 400 million years. Approximately 90% of all plants associate with mycorrhizal fungi of various types over the course of their lives. Some mycorrhizal fungi associate with specific plants, while others have a wide array of “trade partners” and can also associate with many through their mycelial networks. Certain plants require this symbiotic relationship in order to grow optimally and are known as obligate mycotrophs. Plants that do not require mycorrhizae but do benefit from them are known as facultative mycotrophs, and then there are plants that do not associate with mycorrhiza at all, known as non-mycotrophs.
Above: Roots inoculated with endomycorrhizal fungi. The thin filaments are hyphae. (Credit: Ari Singer for DYNOMYCO™)
There are five types of mycorrhizal fungi on the planet currently identified by scientists:
- Arbusuclar mycorrhizal Fungi (AMF)
- Ecotmycorrhizal Fungi (ECM)
- Orchid mycorrhizae
- Ericoid mycorrhizae
- Monotropoid mycorrhizae
The first two on the list, AMF and ECM are the most prevalent and we will elaborate on these, whereas the remaining three types of fungi are less common in commercially available products and form symbiotic relationships with a smaller array of plants.
- Arbuscular mycorrhizal Fungi (AMF): The most common of all fungi. AMF associate with approximately 90% of all plants on earth, among them cannabis. These fungi penetrate cell roots and create a network within and outside of the root. The fungus creates an arbuscule within the plant cell where nutrients, water and minerals brought by the fungi are exchanged for carbohydrates from photosynthesis. AMF do not produce any fruiting bodies (mushrooms) and reproduce asexually below ground, so if you add an endomycorrhizal inoculant to your soil and see a mushroom sprouting from it, it’s from the soil and not the mycorrhizal inoculant.
- Ectomycorrhizal Fungi (ECM): This group of mycorrhizal fungi associate with roughly 5% of plant species, mainly hardwood trees such as Pine, Douglas Fir, Birch, Oak and others. ECM do not penetrate the cell roots of plants like AMF, rather they surround them. The exchange between fungi and host is different due to this. ECM reproduce sexually via fruiting bodies, i.e mushrooms. Examples of these mushrooms are truffles and porcini. It’s important to note that ECM will not associate with cannabis plants since they are not hardwoods!
Of the five groups of fungi mentioned, only one forms symbiotic relationships with cannabis and that is the Arbuscular Mycorrhizal Fungi (AMF). Furthermore, within this category only several species of AMF actually associate with cannabis plants.
How do mycorrhizae work?
The symbiotic relationship is fairly simple. The plant gives the fungus carbohydrates and, in return, the fungus provides the plant with the necessary nutrients it needs. As the plant develops and needs nutrients, it sends carbohydrates down to the fungi in order to support their development. The exchange of nutrients for carbohydrates is done in the arbuscules. These are “tree-like” structures inside the plant cell.
Why you should be adding mycorrhizal fungi to your garden
There are many benefits to adding mycorrhizal fungi to your garden. We’ve listed a few for you here.
- Creates a living rhizosphere – When adding a biological element to a growing operation it tends to create more life. The addition of mycorrhizae will help other microbes thrive, for instance beneficial bacteria. The hyphae create a mycelial super-highway upon which bacteria can navigate on and around the rhizosphere. In this video you can see how they move! These bacteria also play pivotal roles, from nitrogen fixation all the way to plant protection. This living rhizosphere creates a new ecosystem where all the organisms benefit from the presence of one another and help each other, compared to an inert media with no biology in it (otherwise known as dirt). A win-win situation.
- Larger root surface – In undisturbed soils the mycelial network can extend for miles and connect multiple plants together, sharing the same fungal network. A larger root surface area will help in many things, such as water, nutrient and mineral absorption. Another thing this will help with is transplant shock. Plants inoculated with mycorrhizal fungi have higher survival rates and show more vigour compared to when there is no symbiosis between the two.
- Defense mechanism – Research has shown that mycorrhizal fungi can protect plants against certain soil-borne pathogens, such as Fusarium, Pythium and parasitic nematodes.
- Increased nutrient uptake – The AMF will help absorb NPK but also provide the plant with microelements such as iron, zinc, manganese and others. This is especially important when it comes to flower production. With the help of AMF, the plants can absorb a higher amount of phosphorus translating into higher yields and larger buds!
- Abiotic stress tolerance – Plants that formed a mycorrhizal association will enjoy a higher tolerance level to the following:
- pH and salinity (EC)- The fungi lower the EC of the soil and therefore affect the pH and EC levels, making the soil more suitable for plants to live in and prosper. Read up more about this in this research here.
- Drought – Mycorrhizal plants are able to “reach” across great distances in search of water. The hyphae extend past the rhizosphere and spread out into areas that plant roots cannot physically access. When water becomes scarce, this network can save a plant’s life.
- Glomalin production – A glue-like glycoprotein secreted by endomycorrhizal fungi, which helps bind soil particles together, improves its stability and helps prevent soil erosion. Scientists have proven the correlation between the presence of glomalin and the primary productivity of an ecosystem. If you are beginning to build your soil, mycorrhizal fungi are key to a healthy, thriving growing media.
Application of mycorrhizal fungi
The earlier the application in the plant’s life, the better. Early application is also simpler, and there is a higher chance for successful inoculation. This will result in benefits that can be clearly seen when looking at side-by-side comparisons. Due to the short life cycle of cannabis plants it is key to inoculate early. Trees for instance are perennial plants and can develop a hyphal network over several years, whereas with cannabis plants there isn’t that window of opportunity. Furthermore, most cannabis growing is done indoors in pots with new, sterile soil and so the plants can’t connect to an established hyphal network and don’t have the luxury of waiting for this to happen. Due to this the higher the concentration of the product you are applying, and the earlier in the plants life, the more impact it will have on your plant. In commercial trials, we’ve seen differences in plant height, width and health in as little as two weeks!
Plants treated with DYNOMYCO™ on the left compared to untreated plants. This photo was taken 2 weeks after inoculation (credit: Ari Singer for DYNOMYCO™).
Below are several of the application methods we recommend using. Remember, the earlier the better!
1. Mix your inoculant into your growing media – Apply your inoculant as instructed on the label, mix it uniformly into your media and you are done. This method will guarantee that the fungi is distributed uniformly in the soil and there to meet the roots as they begin spreading out in the pot in search of food.
Applying mycorrhizal fungi at the transplantation stage, moments after leaving the propagator and into its first pot (credit: Ari Singer for DYNOMYCO™).
2. Planting hole application – Place your inoculant at the bottom of the planting hole at transplantation and apply at the recommended rates. This will help reduce transplantation shock as explained above.
Planting hole application. Before placing your plant in the hole, add your inoculant to the planting hole (Credit: Ari Singer for DYNOMYCO™)
3. Root ball dusting/coating – This is done at transplantation time. Place some of your inoculant in a container large enough to fit the root ball of your plant. Wet your soil a bit, then roll the root ball in the inoculant so that it covers the sides and bottom uniformly or sprinkle it on top like rainbow sprinkles on ice cream. Once the entire root ball is coated uniformly, you can place it into the planting hole.
Root ball coating of young plugs. Make sure to wet your roots so that the inoculant can stick onto the root ball (credit: DYNOMYCO™)
These are only a few of the many benefits of mycorrhizal fungi and their application methods. Familiarizing yourself with the fascinating world of soil microbes and mycorrhizal inoculants will allow you to explore new cultivation methods and become a better and more efficient grower.