Figure 4.

Leaf–gas exchanges in the control (0 NaCl) and the treated (15 g L⁻¹ NaCl) plants of guayule (P. argentatum). (A) CO₂ assimilation rate, A; (B) stomatal conductance, gs; (C) transpiration rate, E; (D) intercellular CO₂ concentration, Ci; (E) instantaneous water-use efficiency, A/E; (F) intrinsic water use efficiency, A/gs. Values are means ± standard error (SE) of six biological replicates or plants (n = 6). One-way ANOVA (p ≤ 0.05) was applied to evaluate the effect of the NaCl treatment. n.s.: not significant; * and **: significantly different at p ≤ 0.05 and p ≤ 0.01, respectively.