KindHarvest summary: Arbuscular mycorrhizal fungi form partnerships with crop roots, exchanging access to water and nutrients for plant carbon. Research in wheat suggests this relationship can influence how efficiently plants use nitrogen, particularly during grain filling, although responses differ among varieties.
Roots and fungi contribute at different times
In three complementary experiments, pre-flowering nitrogen uptake depended mainly on root traits. Mycorrhizal fungi had a stronger relationship with the conversion of nitrogen already taken up into grain, possibly because fungal phosphorus supply supported photosynthesis during grain filling.
Variety affects the response
After flowering, fungal nitrogen uptake increased, and much of the labelled nitrogen acquired through the mycorrhizal pathway was allocated to grain. However, varieties with different nitrogen-use characteristics responded differently. An inoculant that helps one crop genotype or soil may have little benefit in another.
What this means for inoculation
The study supports managing conditions that favour useful mycorrhizal relationships, but it does not justify assuming every commercial inoculant will reduce fertiliser needs. Existing fungal communities, phosphorus status, disturbance, product viability and crop variety all matter. Replicated untreated strips and root-colonisation checks are valuable before changing a nutrient programme.
Related KindHarvest reading
For a broader look at biological inputs, read Biological products: The new tool of agriculture.
Source and credit
This KindHarvest Team research brief follows a 2022 Top Crop Manager report on research by Wen-Feng Yang and colleagues. The original magazine page is currently unavailable, so the link now points to the peer-reviewed paper. Read the full study in New Phytologist.