Multiply and Inoculate Indigenous Mycorrhizal Fungi
1. Presentation
Characterization of the technique
Description of the technique :
Within the framework of the SYSTEMYC project[1] (INRA Antilles-Guyane), 3 strategies have been identified to promote the mobilization of mycorrhizae in cropping systems :
- Densify existing mycorrhizal networks by implementing favorable techniques : reduction of synthetic chemical inputs and limitation of soil tillage;
- Promote the connection between mycorrhizal fungi and cultivated plants (see sheet Cultivate mycorrhizal species);
- Produce propagules (fragments of mycorrhizal roots, spores or filaments) by multiplication.
Here we focus on the propagule production strategy, by multiplication, with a view to their inoculation.
Indeed, although mycorrhizal fungi are present in most cultivated and uncultivated soils, they can also be multiplied, industrially or artisanally, to then be inoculated into the plot. Three origins of mycorrhizal fungal strains are distinguished, with varied multiplication possibilities :
- Standardized : They can be produced industrially in vivo (in open soil, on inert substrate, in hydroponics or aeroponics) or in vitro (on transformed roots). They are marketed as mixtures of propagules associated with biofertilizers, substrates or seed coatings. They have a broad colonization spectrum, a high multiplication rate and are marketed in association with liquid biofertilizers (fertigation), substrates such as potting soil, clay for seed coating and to mix with sowing substrate (see experimental results on vegetable crops by CA 56).
- Selected local (listed) : Dedicated to their territory of origin, they can be multiplied within regional production units, on different soil types to adapt to specific pedoclimatic conditions.
- Indigenous (unlisted) : Dedicated to a small agricultural region, they are multiplied artisanally by regional production units or directly on the farm. This production takes place in open soil or on substrate (gravel, pumice, perlite).
Details on the technique :
For more information on multiplication and inoculation, consult the sheet Multiply mycorrhizal fungi on your farm (INRA, 2017).
Multiplication of indigenous strains
Carried out artisanally, it allows multiplication especially of strains originating from the farm's soil. Necessary are :
- a tank, pot or trench in the plot, at least 20 cm deep, to serve as a multiplication tank;
- an inert substrate (perlite, gravel, pumice, ...);
- soil taken from an uncultivated area of the farm (without fertilizer or pesticides), from the soil horizon between 10 and 25 cm depth. It will provide the indigenous strain;
- seeds or seedlings of mycorrhizotrophic plants (i.e. plants that mycorrhize the most).
(Source : Mycorrhizae, Bio Savane, 2016)
Harvest
2 to 3 months are necessary for the establishment of a mycorrhizal symbiosis. Stop watering 1 week before harvest to stimulate massive production of reproductive spores. Collect roots and cut into 1 cm fragments. Dried and mixed with soil, they will constitute the inoculum.
Inoculation
The inoculum can be mixed with the sowing potting soil or spread in the field before planting, at a rate of 10 to 30 g of roots per 5 kg of potting soil or soil.
Warning : Mycorrhization is a complex process. For any initiative to produce mycorrhizal fungi on the farm, evaluation of root mycorrhization rates is necessary. It relies on a destructive method of decolorization/staining of root structures and their observation under a binocular magnifier or microscope, requiring specialist expertise.
Implementation period On established crop
At planting
Spatial scale of implementation Plot
Farm
Application of the technique to...
All crops : Sometimes difficult to generalize
It is necessary to use mycorrhizotrophic plants for multiplication, especially legumes (pea, bean, ...), alliums (leek, onion ...) and grasses. The varietal effect is important : rustic and less selected varieties are generally more favorable to the development of the mycorrhizal network.
Also, brassicas and chenopodiaceae do not allow symbiosis with mycorrhizal fungi.
All soil types : Sometimes difficult to generalize
During the multiplication stage, use soils that have not received fertilizer or pesticides.
After inoculation, limit excessive inputs of mineral fertilizers and livestock effluents, which in too large quantities are unfavorable to mycelium development.
All climatic contexts : Easily generalizable
Regulation
POSITIVE influence
Marketing subject to approval as Fertilizing Materials or crop supports (articles L.255-1 to L.255-11 of the Rural Code and maritime fishing).
2. Services provided by the technique
Management of diseases
Once established, mycorrhization improves plant tolerance to root diseases through two mechanisms:
- modification of root morphology and their exudates, creating an unfavorable environment for the development of pathogenic organisms in the soil;
- stimulation of the plant's natural defense mechanisms against pathogens.
Effect level : LOW, if used alone, to be combined
Confidence index : HIGH
COMPLEMENTARY TECHNIQUE(S)
Practice no-till cropping techniques (TCSL)
INCOMPATIBLE TECHNIQUE(S)
Nutrient supply
Introducing species favorable to mycorrhizal fungi greatly increases soil exploration by extending the root system through the mycelium. Plant mineral nutrition is thus improved, especially for poorly mobile elements such as phosphorus.
Effect level : LOW, if used alone, to be combined
Confidence index : HIGH
COMPLEMENTARY TECHNIQUE(S)
Limit mineral fertilizer inputs
INCOMPATIBLE TECHNIQUE(S)
3. Effects on cropping system sustainability
“Environmental” criteria
Effect on water quality : Increasing
Introducing species capable of symbiotic association with mycorrhizal fungi allows
- better interception of phosphorus, thus limiting its transfer to water;
- reduction of pesticides and associated pollution.
Effect on fossil resource consumption : Decreasing
Promoting mycorrhization requires reduced soil tillage, thus reducing associated fossil energy consumption.
Also, it limits mineral fertilizer inputs (especially phosphorus) whose manufacture requires fossil resource consumption.
“Agronomic” criteria
Productivity : Increasing
Inoculation of indigenous strains should have a positive impact on yield. Indeed, the symbiotic association with mycorrhizal fungi tends to promote crop tolerance to various biotic (bioaggressors…) or abiotic (water stress…) stresses in addition to improving mineral nutrition.
Soil fertility : Increasing
Inoculation aimed at densifying the mycorrhizal network ultimately limits mineral fertilizer inputs (especially phosphorus) thanks to better soil exploration capacity.
Also, the symbiotic association of cultivated species with mycorrhizal fungi allows better soil exploration, thus better utilization of available mineral elements. Moreover, the production of glomalin by these fungi contributes to improving soil organic matter content and thus its structural stability.
Water stress : Decreasing
The symbiotic association of cultivated species with mycorrhizal fungi allows better soil exploration. Ultimately, densification of the mycorrhizal network will allow better utilization of available water.
“Economic” criteria
Operating costs : Decreasing
The cost of multiplying indigenous strains is minimal compared to the cost of using standardized strains available commercially (see economic study page 9 of an experiment on vegetable crops CA 56).
It is estimated that mineral fertilizer inputs could be reduced by one third to one quarter depending on soil types and crop nature if mycorrhization were fully utilized (Gianiazzi V., INRA, in Cultivar October 2009).
Margin : Increasing
Beyond reducing fertilization costs and the low cost of multiplying indigenous strains, better crop resistance to abiotic (drought, salinity) and biotic (pathogens) stresses should improve profitability at the campaign and rotation scale.
“Social” criteria
Working time : Variable
Implementing strategies to develop the mycorrhizal network between cultivated plants and fungi may require changes in practices (such as abandoning deep tillage in favor of shallower work, the introduction of rhizotrophic crops in rotation). Depending on the changes made, the impact on working time can vary (increase or decrease).
4. Favored or disadvantaged organisms
Favored Pests
| Organism | Impact of the technique | Type | Details |
|---|
Disadvantaged pests
| Organism | Impact of the technique | Type | Details |
|---|---|---|---|
| root-knot nematode | MEDIUM | pest, predator or parasite | |
| gall nematode | MEDIUM | pest, predator or parasite |
Favored Auxiliaries
| Organism | Impact of the technique | Type | Details |
|---|---|---|---|
| Mycorrhiza | HIGH | Soil functional organisms |
Disadvantaged auxiliaries
| Organism | Impact of the technique | Type | Details |
|---|
Favored climatic and physiological accidents
| Organism | Impact of the technique | Details |
|---|
Disadvantaged climatic and physiological accidents
| Organism | Impact of the technique | Details |
|---|---|---|
| Drought | Densification of the mycorrhizal network allows better soil exploration and better crop resistance to water stress |
5. To learn more
- Multiply mycorrhizal fungi on your farm
- -INRA - INRA Antilles-Guyane Center - ASTRO, Technical brochure, 2017
- Mycorrhiza : a research axis to reduce fertilizer input
- -Milou C.
Cultivar, Press article, 2009
10th Bourgogne-Nature Meetings, Press article, 2014
Quae, Book, 2013
- Experimentation : Benefits of mycorrhization for various winter and summer crops
- -Maët Le Lan (SEHBS - CA 56)
Organic vegetable technical meeting, Professional report, 2012
6. Keywords
Pest control method : Cultural control
Mode of action : Mitigation
Strategy type regarding pesticide use : Redesign
Appendices
Est complémentaire des leviers
- Plant legumes in intercrop
- Limit mineral fertilizer inputs
- Practice no-till cropping techniques (TCSL)
Contribue à
Favorise les auxiliaires
Défavorise les bioagresseurs suivants
Défavorise les accidents climatiques
- ↑ SYSTEMYC Project https://ecophytopic.fr/recherche-innovation/proteger/projet-systemyc
