Plant water status of apple trees and its measurement in the field. I. The dye technique for measurement of leaf water potential

Abstract

A suitable field index of plant water stress was required for studies involving water usage by apple trees. A dye technique, developed after Shardakov's technique, and modified for use with leaf discs, is described. An assessment of the effects of disc size and equilibration time on measured water potentials is made for three apple varieties under different stress conditions. The larger disc size (16 mm diam.) and an equilibration time of 4 hr were chosen to minimize early "time" effects and contamination errors, which are discussed in relation to measured potentials.