The plant growth promoting microbiome increases grapevine resistance to drought stress : a collaborative study between Fondazione Bussolera Branca, Le Fracce farm and Milan Universities

Drought affects grapevine production worldwide. To protect grapevine from water stress, an eco-friendly approach was adopted, establishing a large microbial collection from root tissues and rhizosphere of different rootstocks from the vineyards of Le Fracce Farm in Oltrepo Pavese, an area in north Italy that experiences summer drought. Nine strains, endowed with multiple plant growth promoting activities, were assayed under greenhouse conditions on plants grown in the clay-rich soil of the vineyard of origin. Bacteria treated plantlets of SO4 and 420A rootstocks were exposed to water stress (50% of the field water capacity) for over 30 days. Water stress affected uninoculated control plants that presented alterations of physiological parameters, while grapevine plants treated with bacteria appeared healthier with 10-20% higher photosynthetic levels. Plant biomass after 30 days of growth under water stress was 20-40% higher in treated plants than the untreated controls. The data highlight the biotechnological potential of PGP bacteria for protecting grapevine from drought.