Cultivating Mycorrhizal Species
1. Presentation
Characterization of the technique
Description of the technique:
Within the framework of the SYSTEMYC project (INRA Antilles-Guyane), 3 strategies have been identified to enhance the mobilization of mycorrhizae in cropping systems:
- Densify existing mycorrhizal networks by implementing favorable techniques: reduction of synthetic chemical inputs and limitation of tillage;
- Promote the connection between mycorrhizal fungi and cultivated plants;
- Produce propagules by multiplication (see sheet Multiply and inoculate indigenous mycorrhizal fungi).
Here, the focus is on the strategy consisting of promoting the connection between mycorrhizal fungi and cultivated plants, by favoring the introduction of mycorrhizotrophic species in the rotation, i.e., species capable of hosting mycorrhizae on their roots.
Cultivating these species helps promote the formation and densification of mycorrhizal networks in fields, which provide useful services to cultivated plants (improved uptake of soil nutrients, bioprotection against pathogens - nematodes, fusarium wilt, rhizoctonia..., stimulation of the plant's natural defenses and increased vigor, etc.).
Mycorrhizotrophic plants can be grown in pure stands, in association, as cover crops, or in active fallow.
Which crops are concerned?
All cultivated species, except brassicas (rapeseed, mustard...) and chenopodiaceae (beets), have the capacity to form symbiotic associations with mycorrhizal fungi.
The potential for mycorrhization is higher for certain species such as legumes (pea, bean, ...), alliums (leek, onion ...) and grasses (sorghum, millet, corn, ...).
Details on the technique:
The sole cultivation of species favorable to mycorrhization is not sufficient to establish mycorrhizal networks. These networks are strongly disadvantaged by practices such as tillage, excessive fertilization based on mineral fertilizers, and the use of phytosanitary products. Solutions aiming to artificially enhance soil inoculation can be implemented on deficient soils (see sheet Multiply and inoculate indigenous mycorrhizal fungi).
Also be careful not to confuse mycorrhization with symbioses associating legumes and bacteria, which are responsible for atmospheric nitrogen fixation.
Implementation period On established crop
At planting
Spatial scale of implementation Field
Farm
Application of the technique to...
All crops: Generalization sometimes delicate
The varietal effect is important and only brassicas and chenopodiaceae do not allow symbiosis with mycorrhizal fungi.
Rustic and less selected varieties are generally more favorable to the development of the mycorrhizal network.
All soil types: Generalization sometimes delicate
Soils receiving large amounts of livestock effluents are unfavorable to mycelium development.
All climatic contexts: Easily generalizable
Regulation
POSITIVE influence
Marketing subject to approval as Fertilizing Materials or crop substrates (articles L.255-1 to L.255-11 of the Rural Code and maritime fishing).
2. Services provided by the technique
Disease management
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 technique used alone, to be combined
Confidence index: HIGH
COMPLEMENTARY TECHNIQUE(S)
Practice no-till farming techniques (NTFT)
INCOMPATIBLE TECHNIQUE(S)
Nutrient supply
Introducing species favorable to mycorrhizal fungi greatly increases soil exploration by extending the root system through the mycelium. Plant nutrition in mineral elements is thus improved, especially for poorly mobile elements such as phosphorus.
Effect level: LOW, if technique used alone, to be combined
Confidence index: HIGH
COMPLEMENTARY TECHNIQUE(S)
Limit mineral fertilizer inputs
INCOMPATIBLE TECHNIQUE(S)
3. Effects on the sustainability of the cropping system
"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 tillage, thus reducing fossil energy consumption linked to tillage.
It also limits mineral fertilizer inputs (especially phosphorus) whose manufacture requires fossil resource consumption.
"Agronomic" criteria
Productivity: Increasing
The symbiotic association with mycorrhizal fungi tends to enhance crop tolerance to various biotic stresses (bioaggressors…) or abiotic stresses (water stress…) in addition to improving mineral nutrition. The impact on yield should therefore be positive.
Soil fertility: Increasing
Introducing species favorable to mycorrhization limits mineral fertilizer inputs (especially phosphorus).
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 and thus better utilization of available water.
Functional Biodiversity: Increasing
Introducing cultivated species capable of symbiotic association promotes the development in soil of mycorrhizal fungi and associated bacteria beneficial to plant growth.
"Economic" criteria
Operating costs: Decreasing
Introducing species capable of symbiotic association with mycorrhizal fungi should limit input use and thus reduce associated costs.
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 exploited (Gianiazzi V., INRA, in Cultivar October 2009).
Margin: Increasing
Beyond the reduction of fertilization costs, 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
Seeking to develop the mycorrhizal network, in addition to introducing favorable species, may require practice changes (such as abandoning deep tillage in favor of shallower tillage). Depending on the changes made, the impact on working time can vary (increase or decrease).
4. Organisms favored or disadvantaged
Favored Bioagressors
| Organism | Technique impact | Type | Details |
|---|
Disadvantaged bioagressors
| Organism | Technique impact | Type | Details |
|---|---|---|---|
| root nematode | MEDIUM | pest, predator or parasite | |
| root-knot nematode | MEDIUM | pest, predator or parasite |
Favored Auxiliaries
| Organism | Technique impact | Type | Details |
|---|---|---|---|
| Mycorrhiza | STRONG | Soil functional organisms |
Disadvantaged Auxiliaries
| Organism | Technique impact | Type | Details |
|---|
Favored climatic and physiological accidents
| Organism | Technique impact | Details |
|---|
Disadvantaged climatic and physiological accidents
| Organism | Technique impact | Details |
|---|
5. For further information
- Mycorrhizae: Living networks serving crops
- -Chave M., Perrin B., Dufils A.
INRA, Technical brochure, 2017
- Mycorrhizae, promising fungi for agriculture
- -Agroperspectives, Press article, 2011
- Microorganisms to boost your crops
- -Agriculture Nouvelle, Website, 2012
- Mycorrhiza: a research axis to reduce fertilizer input
- -Milou C.
Cultivar, Press article, 2009
- Mycorrhizae
- -Bio Savane - Cultivons Autrement, Technical brochure, 2016
- Mycorrhizae, a plant-fungus alliance discovered in 1885 and still poorly known?
- -Daniel Wipf
10th Bourgogne-Nature Meetings, Press article, 2014
6. Keywords
Bioagressor control method: Cultural control
Mode of action: Mitigation
Strategy type regarding pesticide use: Redesign
Annexes
Est complémentaire des leviers
- Plant legumes in intercrop
- Limit mineral fertilizer inputs
- Practice no-till farming techniques (NTFT)
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