Joint last authors of the framework:
Arbuscular mycorrhizal fungi (AMF) are beneficial plant symbionts that provide important ecosystem services and have been shown to improve plant fitness and yields. The majority of terrestrial plants, including most agricultural crops, form this symbiotic relationship. Managing AMF has been proposed as a tool to improve the sustainability of our food production systems and the application of arbuscular mycorrhizal (AM) inoculants is one method to bolster the natural mycorrhizal activity.
Various studies demonstrate the positive effects of AM inoculation on plant yield and ecosystem services, which highlights the environmental and economic potential of commercial inoculants. However, a recent global study showed that over 80% of inoculants do not result in mycorrhizal root colonization when tested under controlled conditions. This is either due to reduced viability of the AM propagules or not enough propagules being present.
To improve this situation, we propose a framework which sets out the necessary quality criteria to produce viable AM inoculum. These quality criteria are verified through a standardised bioassay for testing inoculum under controlled conditions. The proposed quality criteria focus on inoculum composition and viability, carrier materials and packaging and labelling.
This framework could be adapted by regulatory agencies as a first step towards the mandatory quality control of AM inoculants. Ensuring that these quality criteria are met by the AMF industry would improve consumer trust and the uptake of commercial AM inoculants by producers.