Arbuscular mycorrhizal fungi (AMF) - MYCORRHIZAE    (Myco = fungus, Rhiza = root)
 

What are mycorrhizae?
The associations between roots and fungi are called mycorrhizae. These symbiotic arrangements have been found in about 90% of all land plants, and have been around for approximately 400 million years. Plant roots are hospitable sites for the fungi to anchor and produce their threads (hyphae). The roots provide essential nutrients for the growth of the fungi. In return, the large mass of fungal hyphae acts as a virtual root system for the plants, increasing the amount of water and nutrients that the plant may obtain from the surrounding soil. In soil that has been disturbed by human activity, the quantity of mycorrhizae decreases drastically so that there are not enough of them to produce a significant benefit on plant growth and health, hence the importance to compensate for this lack.

 

BENEFITS:
The benefits of mycorrhizae to plants are often related to increased nutrition and water uptake as well as enhanced tolerance to environmental stress.

 

• Nutrients and water - When mycorrhizae are present, plants are less susceptible to water stress. Not only do the fungal threads help to bring water and nutrition into the plant, but they also can store them for use when rainfall is sparse and temperatures are high. When organic matter (compost) is added to improve a soil, mycorrhizae are important in making its nutrients available. The residual organic matter and the hyphae improve the structure of the soil. Recent research indicates that the fungi even help break down rock, increasing availability of the essential nutrients within, such as potassium, calcium, zinc and magnesium. [1]

• Disease resistance - Mycorrhizae also help the plant resist infection by other fungi and even bacteria. This may be because the plant, being better nourished, is healthier and has better resistance to the invader. It may also be that the large physical presence of one fungus impedes infection by others. Another possibility is that either the plant or the fungus produces compounds that prevent infection by pathogens. [1]

• Interaction with other soil microbes — a cycle of benefit - Plants interact with other organisms in the soil. Many of these microorganisms fertilize plants by "fixing" nitrogen, which is then available for plant growth. When mycorrhizae are present, the number and vitality of these nitrogen fixers increase. As a result, the plant‘s health and vigor improves, as does the health and vigor of the beneficial fungi. [1]

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IN SUMMARY -THE BENEFITS OF MYCORRHIZAE:
Mycorrhizal fungi allow plants to draw more nutrients and water from the soil. They also increase plant tolerance to different environmental stresses. Moreover, these fungi play a major role in soil aggregation process and stimulate microbial activity.
•    Produce more vigorous and healthy plants
•    Increase plant establishment and survival at seeding or transplanting
•    Increase yields and crop quality
•    Improve drought tolerance, allowingwatering reduction
•    Enhance flowering and fruiting
•    Optimize fertilizers use, especially phosphorus
•    Increase tolerance to soil salinity
•    Reduce disease occurrence
•    Contribute to maintain soil quality and nutrient cycling
•    Contribute tocontrol soil erosion
•    Higher transplanting success

 

 

[1] MYCORRHIZAE ; Angela M. O’Callaghan, Ph.D. Southern Area Social Horticulture Specialist http://www2.nau.edu/~gaud/bio300/mycorrhizae.htm