Mycorrhiza
/ˌmaɪkəˈraɪzə/
Definition
Mycorrhiza refers to a symbiotic association between certain fungi and plant roots. In this relationship, fungal threads called hyphae grow on or into the root, extending into the soil and helping the plant take up water and nutrients, especially phosphorus. In return, the fungus receives sugars made by the plant. The term describes the root-fungus partnership itself, not the fungus alone, and it occurs in forms such as ectomycorrhiza and arbuscular mycorrhiza.
Biological Role
- Nutrient reach beyond roots: It extends a plant’s access to soil through fine fungal threads, increasing uptake of relatively immobile nutrients, especially phosphorus, and often improving water capture in dry or low-fertility soils.
- Different partnership patterns: Major forms include arbuscular associations in many crops and ornamentals, and ectomycorrhizal associations common in many trees such as pines and oaks, with each type interacting with roots in a different way.
- Support during establishment: Young plants often establish more successfully when compatible fungal partners are present, particularly after transplanting or in disturbed soils where natural fungal networks may be sparse.
- Sensitive to soil conditions: Its activity can be reduced by soil compaction, waterlogging, severe disturbance, or excessive phosphorus fertilization, so benefits vary with site conditions rather than occurring equally in every planting.
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