By Lloyd Christopher Jones, Jr., UC Master Gardener of Napa County.
As a graduate of Cornell University’s Master of Professional Studies program, I did my capstone project on the symbiotic relationship between arbuscular mycorrhizae fungi (AMF) and Vitis vinifera ‘Pinot Noir’.apes. I now believe AMF benefits all plants, both agricultural and horticultural. My research indicated greater root length colonization of the fungi, but I could not determine the long-term benefits due to the short duration of my research.
AMF are beneficial microorganisms that form a symbiotic relationship with plant roots. They can be introduced to the soil, but in most cases, they are present naturally. They are an extension of roots and help with the uptake of water and nutrients, primarily phosphorus. In many soils, phosphorus is “tied up” and highly immobile—hence hard for the plant to access. AMF makes the uptake easier.
You will find these magnificent microorganisms at work in the rhizosphere, the zone surrounding a plant’s roots. Like other fungi they produce spores, which attach to the host and begin to spread when conditions are right.
Soil health is important to all plant life. To have good soil health, microorganisms need to be present along with adequate levels of organic matter. AMF is one of those necessary microorganisms alongside other fungi, bacteria, nematodes and soil-dwelling insects. When fully decomposed, organic matter is known as humus.
Beneath the surface is a highly complex biological ecosystem, including an abundance of fungal networks. Fungi help decompose organic matter, making nutrients more available to plants. They help with water uptake and scavenge nutrients. In the case of AMF, they associate with plant roots to form a symbiotic relationship.
AMF form arbuscules and vesicles within plant roots. Arbuscules are found within the root cells and have a branched treelike structure. Vesicles look like balloons and are the storage systems within the root cell.
AMF begin their life cycle as a spore. The spore germinates when conditions favor its survival and grows hyphae. The hyphae grow in the soil, forming mycelium, a threadlike root structure. These hyphae are attracted to roots by root secretions, known as exudates. The hyphae penetrate the roots. Arbuscules and vesicles form in the root cells. The arbuscles help bring phosphorus, water and other nutrients to the plants and in return the plant brings carbon to the AMF. Each organism aids the other, proving the benefits of having AMF in the soil.
For my student project, I extracted core samples from the root zone with an auger and hand drill, then air dried and fastidiously separated them to reveal the roots. The roots were delicately rinsed, stained and examined under a high-magnification microscope. The arbuscules weren’t easily visible but were present in small quantities; the vesicles and hyphae were evident.
The root length colonization was higher than 70% for clone 101-14 and about 60% for clone 3309C compared to the control which was 40% for clone 101-14 and just below 40% for clone 3309C. The average hyphae length was 40% for clone 101-14 and 25% for clone 3309C compared to the controls which were lower. The average arbuscules and vesicles were higher than the control as shown in the graphs below.
AMF products can be sourced online or at your local nursery in formulations for the home gardener. They are natural amendments that can be helpful with soil and plant health.
Workshop: Join UC Master Gardeners of Napa County for a workshop on “Planning and Creating a Native, Low-Water, Pollinator or Succulent Garden” on Saturday, June 27, from 10 am to noon, at University of California Cooperative Extension, 1710 Soscol Avenue, Napa. learn how to design, plant, and maintain a sustainable garden in your own landscape. Register here.
Library talk: Join UC Master Gardeners of Napa County and Napa County Library for a free talk on “Succulent Garden Design for our Changing Climate” on Thursday, July 2, from 7 pm to 8 pm via Zoom. Succulents add variety, color and texture to your garden and in general require little water and maintenance. Explore succulent garden design concepts embracing biodiversity and wildfire resilience. Register to receive the Zoom link.
Help Desk: The Master Gardener Help Desk is available to answer your garden questions. Use our online Plant Problem Help Form or email us at mastergardeners@countyofnapa.org. Include your name, address, phone number and a brief description of the problem. You can also visit us in person on Mondays and Fridays from 10 am until 1 pm at the University of California Cooperative Extension Office, 1710 Soscol Avenue, Suite 4, Napa.
Photo courtesy of pexels-spencphoto-28517745
Graphics courtesy of the author