Seasonal Trends of Grapevine Physiological Performance and Soil Water Content of 'Sangiovese' (Vitis vinifera L.) Field Plots under Regulated Deficit Irrigation

摘要

Irrigation practices in areas featuring ample fluctuations in summer precipitations require to develop easy-handling water management strategies to define time of application and water volumes to be used. Thus monitoring soil water content (SWC) underneath vine canopy by a capacitance probe was tested as a tool for control irrigation and tracking vine physiological performance along the season and under uncertain meteorological conditions in the Marche (central Italy). Control not-irrigated plots (10) were compared to RDI treatments based on the restitution of 33% (II) or 70% (12) of crop évapotranspiration of the previous week. Grapevines were irrigated when midday leaf water potential (Ψ1) was about -0.9 MPa, net photo-synthesis (P_n) was still high (11 μmol m~(-2) s~(-1)) and SWC in the first 0.6 m depth underneath vine canopy have reached the wilting point (WP) threshold. After drip-irrigation, P_n, Ψ1 and Ψs values increased in RDI treatments compared to control 10 vines. SWC underneath the row raised to values close to the field water capacity (FWC). From the end of July till harvest, in mid-September, Ψ1 decreased around -1.1 MPa, SWC in the first 0.6 m depth lowered below WP, while P_n remained above 8 μmol m~(-2) s~(-1) in all treatments. Thus water absorption during berry ripening took place mainly in deep soil layers in all tested treatments. Strict linear correlations were found among indicators of water status (Ψl, Ψs and SWC), that, in turn, resulted correlated with Pn. In our trial the linear correlation between SWC and Pn accounted for 69% of the total variability. SWC, easily monitored in the field by DΓVINER2000 capacitance probe, was a good indicator of vine water status and physiological performance. All Grapevines experienced only moderate water stress, thus RDI treatments slightly affected yield and grape composition.