Pressure-volume curves and target water potential
Pressure-volume curves were generated for each species to estimate the turgor loss point and select the initial leaf water potential (Ψ) value for all FWU experiments. This target Ψ value corresponded to 70% of the turgor loss point. We followed the bench drying technique (Hinckley et al. 1980) using six randomly selected leaves per species. Briefly, branches were cut underwater, placed in plastic bags to prevent transpiration, and allowed to fully rehydrate. Leaves were then detached from branches, weighed, and placed on a bench to desiccate at room conditions (relative humidity, RH, ~30% and temperature ~22 ºC). Each leaf was re-weighed, and its Ψ was measured with a pressure chamber during the drying period. The procedure was halted when 10 to 15% of the initial leaf mass was lost. Leaves were oven-dried at 80 ºC for three days to calculate their relative water content (RWC) as RWC = (fresh weight–dry weight, DW)/(turgid weight–DW). The turgor loss point was estimated from the pressure-volume curves.