Hydraulic Properties and Water Relations of Vitis Vinifera L. exposed to elevated CO2 Concentratiions in a Free Air CO2 Enrichment (FACE)

Plants of Vitis vinifera (cv. Sangiovese) were submitted to elevated carbon dioxide concentrations in the field, using a FACE array; the experiment took place in a vineyard in Central Italy, throughout two growth seasons. The effects of fumigation on stem hydraulic properties and leaf water relations were evaluated. A significant decrease in stomatal conductance did not result in marked differences in leaf water potentials of FACE plants. Apparently, embolism formation showed to increase and hydraulic sufficiency to decrease after two years of exposure to elevated CO2. The allometric relationships between stem hydraulic conductivity, leaf area and stem cross-sectional area of xylem imply a physiological origin, though being unclearly affected by elevated CO2. The effect of elevated CO2 on water relations and hydraulic parameters of Sangiovese grapevine displayed variation reliant on fumigation time-span. Under these experimental conditions, changes in hydraulic properties in FACE plants did not provide a direct explanation for variations in leaf water relations in comparison with controls.