Best Procedures for Leaf and Stem Water Potential Measurements in Grapevine: Cultivar and Water Status Matter.

The pressure chamber is the most used tool for plant water status monitoring. However, species/cultivar and seasonal effects on protocols for reliable water potential determination have not been properly tested. In four grapevine cultivars and two times of the season (early season, Es; late season, Ls, under moderate drought), we assessed the maximum sample storage time before leaf water potential (Ψ) measurements and the minimum equilibration time for stem water potential (Ψ) determination, taking 24 h leaf cover as control.