Plant water status of apple trees and its measurement in the field. III. Some sources of variation in the water potential of apple leaves in the field

Abstract

Leaf water potentials may vary with leaf insertion height for some species, giving rise to errors dependent on sampling heights. Leaf position and leaf age at one insertion height could also influence measured water potentials. For the apple tree, leaf water potentials determined with the dye technique differed with insertion height. These differences were appreciable and point to the need for standardizing sampling height for routine stress measurement.