Figure 7.

Daily simulated patterns of g_s (A), Ψ_leaf (B), A_{n, tot} (C), and percentage loss of K_x (D) during the progression of a simulated soil drought (SurEau model; Table 1; see “Materials and Methods”). Four scenarios were modeled: (1) both K_leaf and root hydraulic conductance (K_root) were vulnerable to dehydration prior to the turgor loss point (yellow lines); (2) K_leaf was vulnerable but not K_root (red lines); (3) K_root was vulnerable but not K_leaf (light blue lines); or (4) neither K_leaf nor K_root was vulnerable (dark blue lines). The inset in C shows cumulative water-use efficiency (WUE; calculated as A_{n, tot} over total transpiration rate) over time. Scenarios including a vulnerable K_leaf showed leaves that showed highest water-use efficiency, A_{n, tot}, and survived longer under drought conditions.