Farmers and foresters often inoculate seeds with fungal spores to promote plant growth and development. Based on what you have learned about fungi and plant nutrition, explain the rationales behind the seed treatment.
Fungal inoculum applied as seed treatments deliver fungi
directly to the plant rhizosphere. Many beneficial fungi of
agricultural importance are rhizosphere colonising species, with
ability to increase plant growth via a range of mechanisms.The
active components in the inoculum are mycorrhizal fungi propagules
in the form of spores and colonized root fragments.
When one of these colonizing units touches or comes into very close proximity of living root tissue they are activated by minute amounts of specialized root exudates and begin the mycorrhizal colonization process.
The newly colonized root cells begin to send hyphal threads from the young plant’s roots.
The hyphae then begin absorbing moisture and nutrients from the surrounding soil while preventing root disease pathogens through the production of antagonistic exudates.
These processes result in greatly improved chances for survival compared to non-mycorrhizal plants. The colonized plant sprout secures adequate moisture, nutrients and defense against fungal root diseases.
The hyphae quickly grow and spread throughout the surrounding soil, penetrating the tiny spaces between soil particles and colonize even more roots until a massive hyphal network has pervaded the expanded rhizosphere.