Fungal and bacterial amplicon of coir

In the UK, strawberry is mostly grown in coconut coir-substrate under protection. Coir substrate is usually used only for one or two cropping seasons, because continuous reuse of coir without any treatment leads to yield decline. In this study we investigated the changes in bacterial and fungal communities in strawberry roots and bulk coir in relation to: (i) the coir substrate age (cropping seasons), and (ii) oak or beech biochar amendment at planting. Coir age did not affect fungal/bacterial alpha (within-sample) diversity but affected beta (between-sample) diversity. Amendment with either oak or beech biochar did lead to significant changes in either alpha or beta diversity for both fungi and bacteria. Differential abundance analysis indicated that relative abundance of many microbial taxa (ASVs), particularly fungal taxa in strawberry roots, significantly varied with the age of coir. The observed strawberry yield decline in reused coir substrate might be associated with an increase in the relative abundance of a root pathogen, Ilyonectria destructans (ex. Cylindrocarpon destructans). Future research is needed to confirm the role of I. destructans in reused coir on strawberry yield.