Diurnal Changes in Citrus Leaf Thickness, Leaf Water Potential and Leaf to Air Temperature Difference

Diurnal changes in leaf water potential and leaf thickness ofwell-watered citrus trees were found to be highly correlated.Midday decreases in leaf thickness of about 30–35 µm reflected midday decreases in leaf water potential of about1.1–1.3 MPa from predawn values. Leaf water potentialwas also correlated with changes in leaf-to-air temperaturedifference and ambient vapour pressure deficit. Leaf thicknessas well as leaf to air temperature difference could possiblybe used to monitor leaf water status continuously as an indicatorof citrus tree water stress.