Effects of inter-row cover crop termination strategy on grapevine performance and mycorrhizal activity under contrasting seasonal conditions

Cover crop termination influences vineyard functioning, but evidence from Mediterranean rainfed systems are limited. In this study, we aimed to understand how two commonly used termination methods affect vine performance and belowground biological activity in a Mediterranean vineyard. A two-year experiment was carried out in an organic ‘Vermentino’ vineyard, in Tuscany, to evaluate the impact of green manuring (GM) and roller-crimping (R) on grapevine water status, canopy development, yield, must quality, inter-row vegetation dynamics and arbuscular mycorrhizal fungi (AMF) responses. At termination time, total aboveground biomass of groundcover was higher in 2022 (8.5–10.0 t d.m. ha⁻¹) than 2023 (7.0–8.3 t d.m. ha⁻¹). Weed biomass at termination was greater in 2022, especially in R. Post-termination, bare soil cover was lower under R than GM, while weed cover was modestly higher under R (+11–16%). In 2022, differences in grapevine stem water potential (Ψ stem ) emerged only at the end of summer (higher Ψ stem in R than in GM on day of the year - DOY - 220 and 240), without treatment effects on total leaf area (2.8–2.9 m²). In 2023, R maintained higher Ψ stem from DOY 180 to 240, supported larger canopies, and increased grape yield (2.84 and 2.43 kg vine⁻¹, in R and GM, respectively) and pruning weight (0.78 and 0.69 kg vine⁻¹, respectively). Must composition at harvest did not differ between treatments. AMF colonization in vine roots increased in 2022 from 36% to 72% in R, exceeding GM on DOY 260 while mycorrhizal inoculum potential (soil and rhizosphere) varied by year, but no significant differences were measured between termination strategies. Overall, the study shows that roller-crimping can improve vine water status and vigor under wetter conditions while maintaining must quality and supporting AMF activity, offering a viable soil-conserving alternative for Mediterranean vineyards. • The study examined vineyard responses to two cover crop termination strategies. • Roller-crimping improved vine water status and vigor under wetter conditions. • Termination methods did not affect must composition. • AMF colonization was higher in rolled plots under dry conditions. • Mycorrhizal diversity varied mainly with season rather than termination method.