Diurnal courses of stomatal conductance ([g.sub.S]) were taken on leaves of intact trees and trees in potometers, using a steady-state porometer (Model 1600; Li-Cor, Inc.).
This good agreement persisted for as long as [g.sub.S] and [[PSI].sub.L] of trees in potometers were similar to those observed in intact trees (Fig.
A very close agreement between the two techniques was found along the course of two days of observation during which Hyeronima trees in potometers did not show any visible signs of wilting (Table 2).
Leaf water potential and stomatal conductance: In Ochroma, leaves of the control trees exhibited average predawn and midday [[PSI].sub.L] values of -0.24 and -0.83 MPa, while leaves from trees in potometers reached [[PSI].sub.L] values of -0.35 and -1.13 MPa (Table 3), respectively.
The diurnal trend as well as the maximum [g.sub.S] values of control trees and trees in potometers of the two species examined were virtually indistinguishable during the first day of observations (Fig.