Vol. 73 No: 4

Title:
Relations Between Leaf and Stem Water Potentials and Stomatal Conductance in Three Field-Grown Woody Species

Author:
A. NAOR

pp: 431-436

Abstract:
Simultaneous measurements of stomatal conductance (g_s), and leaf (ψ_leaf) and stem (ψ_stem) water potentials were conducted from 0900 hours to early afternoon on field-grown trees of apple, grapevine and nectarine which received different irrigation rates. The correlations of g_s with ψ _stem (r² = 0.85, 0.85, 0.79) was significantly higher than those with ψ_leaf (r² = 0.51, 0.61, 0.37) for apple, grapevine and nectarine, respectively. The high correlation between g_s and ψ_stem has been explained through a qualitative analysis of a water transport model which takes into account the control of g_s by root signals (Tardieu and Davies, 1993). The model suggests that g_s, ψ_leaf, root water potential, root-signal intensity, and transpiration rate are linked in a feedback mechanism which leads to the high correlation of g_s and ψ_stem and causes it to be better than that with ψ_leaf.

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