In situ field comparisons of Citrus jambhiri leaf water potential using hygrometric and pressure chamber methods

Abstract

In an experiment conducted outdoors, using Citrus jambhiri plants, we obtained comparative in situ dew point hygrometer, Psychrometer and pressure chamber water potential measurements. Partial abrasion of the leaf cuticle was effected prior to sealing thermocouple hygrometers against leaf surfaces. Contrary to common belief, the dewpoint hygrometric technique was found to be affected by leaf conductance, and therefore cannot be considered isopiestic. Dewpoint hygrometric water potential values were generally lower than corresponding pressure chamber or psychrometric measurements.