Enhancing vineyard soil mycorrhizal properties and grape and wine phenolic profiles through microbial inoculation and interrow green cover

Grapevine cultivation has to face major challenges for maintaining its long-term resilience, in which soil health is a key factor. Sustainable management options, like service crops and beneficial microbial inocula, have been proposed for preserving soil health and biodiversity in vineyards. Here, commercial and locally sourced arbuscular mycorrhiza-based inocula were applied in combination with a green cover mix in two organic Mediterranean vineyards with different intensity of soil disturbance. Chemical soil properties, mycorrhizal inoculum potential, arbuscular mycorrhizal fungal (AMF) ecology (using high-throughput DNA metabarcoding), and grape and wine physico-chemical characteristics were investigated in the short-term. The local inoculum enhanced soil mycorrhizal activity by 179% in the more intensely cultivated vineyard. The sustainable management treatments increased AMF biodiversity by up to 42% in terms of richness, and induced significant shifts in the community composition at both sites. Nevertheless, the introduced AMF did not outcompete native communities. Grape and wine secondary metabolite profiles showed an enrichment of phenolic compounds by up to 35% – in particular that of anthocyanins, flavan-3-ols, hydroxycinnamic acids and phenolic alcohols – in plots treated with interrow green cover and microbial inocula. Additionally, grape anthocyanin and wine anthocyanin, flavonol and phenolic alcohol contents exhibited strong, and mostly positive correlations with soil AMF diversity. Our data highlighted the modulating effect of vineyard terroir on both mycorrhizal ecology and grape / wine quality responses to the applied treatments. Therefore, service crops and mycorrhiza-based inocula may be feasible tools for improving soil health, microbial biodiversity and agro-ecosystem sustainability in viticulture. This work provides a novel insight into vineyard AMF ecology and the impact of sustainable agricultural practices on grape and wine characteristics in field conditions.