Fig. 2
Piñon Ψmin declines after months of regular watering. Pre-dawn (Ψpd) and mid-day (Ψmd, Ψmin) leaf water potentials of five potted mature piñon pine trees irrigated daily for over one year and measured weekly after acclimatizing for a three month (14 week) period (A). After 5 months of regular watering (“Zone 1”), piñon Ψmin declined by over 1.2 MPa (p < 2.2e−16), and this decrease was maintained for the duration of the study (8 months; “Zone 2”; B). Vertical black dashed line in panel (A) indicates the point after which pre-dawn (orange dashed line) and mid-day (red dashed line) Ψleaf differed significantly for more than two consecutive weeks and Ψmd remained significantly lower than Ψpd. Error bars are standard deviation. Lower case letters indicate significant differences at p = 0.05.
