Stomatal conductance changes in leaves of McIntosh apple trees before and after fruit removal

Abstract

Daytime stomatal conductance of McIntosh apple leaves was variable and relatively high (1.4 to 3.8 mm s−1) up until fruit removal. Leaf chlorophyll content, total leaf water potential, and specific leaf weight were less variable. Stem water content declined linearly by 10% from mid-August to late October. After fruit removal stomatal conductance, leaf chlorphyll content, and total leaf water potential decreased to low levels. Specific leaf weight did not decline until very late in leaf senescence.A simple model of stomatal response to environmental factors was tested and, following calculation of appropriate parameter values, gave acceptable agreement between measured and calculated stomatal conductances.