Abstract
In situ measurements of leaf water potential are important for monitoring the energy state of water in plants. Thermocouple psychrometry is an acceptable measurement method, where leaf water status is inferred by analysis of water vapor pressure adjacent to the leaf surface. Unfortunately, excessive equilibration times, caused by low vapor conductance across the leaf cuticle and vapor sorption in the psychrometer chamber, make in situ sampling difficult. Several methods of removing waxy leaf cuticle have been shown to increase water vapor conductance across the epidermis of the leaf, thus speeding water potential measurement, but have not been compared for relative effectiveness. In addition, mean equilibration time has not been calculated for in situ leaf psychrometers when attached to leaves whose waxy cuticle has been removed. Six waxy cuticle removal treatments were compared to an untreated control to discover which produced a significantly higher conductance of water vapor across the leaf surface. The treatment corresponding to the highest conductance was then used to determine the mean equilibration time of the leaf psychrometer. Six hundred grit sandpaper treatment was found to be the most effective treatment to remove the waxy cuticle. Equilibration was found to be significantly affected by psychrometer cleanliness and plant response to changes in its external environment. By controlling or removing these factors, mean equilibration time for leaves from which the cuticle had been removed was less than 11 min.
Campbell, Colin S (1997). Response of in situ leaf psychrometer to cuticle removal by abrasion. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1997 -THESIS -C353.