Comparisons of Leaf Water Potential and Xylem Water Potential in tomato Plants

Abstract

The rapidity and convenience of the pressure chamber technique for estimating leaf water potentials, especially under field conditions, has been remarked (Boyer 1967; Kaufmann 1968a, 1968b) and demonstrated (Klepper and Ceccato 1969). However, Kaufmann (1968a) showed that it is necessary to exercise caution .in using measurements made with the pressure chamber as direct estimates of leaf water potential. Instead, he recommended that calibration curves should be drawn up for each species, relating measurements of xylem pressure potential obtained with this technique to corresponding known leaf water potentials. The present communication reports such a relation for tomato leaves, which have not previously been studied in this way. Plant age is shown to affect the relation.