Plant water status of apple trees and its measurement in the field. IV. Stomatal aperture, determined by infiltration scoring, as an index of leaf water potential

Abstract

Stomata] aperture has been used by a number of workers as a physiological indicator of plant water status. With apples, early work shows that stomatal aperture may provide a useful and sensitive measure of plant responses to applied water and the onset of stress conditions. Leaf and fruit water potentials of Jonathan, Delicious and Granny Smith apples were measured using a dye method which is described. Compared with a vapour equilibration technique the differences did not exceed ±1 atm. for the 3 varieties tested.