Comments on the psychrometric determination of leaf water potentialsin situ

Summary Leaf diffusion resistances may lower the values of leaf water potentials found byin situ measurements with silver-foil psychrometers. With the instrumentation used, the bias ranges from zero to increasing negative deviations as leaf diffusion resistances become larger than 3.5 cm^-1 sec.Water potentials determined with the dewpoint technique are unaffected by diffusion resistances.In situ measurements by this method may also be carried out with the silver-foil sensor.Hence, one and the same sensor may serve to trace both leaf water potentials and leaf diffusion resistance through dewpoint and psychrometric measurements. re]19760720