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Fig. 4. Dawn to dusk trends in mean total leaf water potential measured with a pressure chamber (
W(PB)) in fully expanded sunlit spring wheat leaves at (a, b) predawn, (c, d) midday (solar noon), and (e, f) sunset for day after 50% emergence (DAE) 43 to 118 during the (a, c, e) 1993 and DAE 41 to123 during the (b, d, f) 1994 growing seasons. Measurement dates correspond with up-pointing arrows shown in Fig. 1b, d. Each mean datum is the pooled average of three to four leaves collected within a 15-min period in four replicate blocks (i.e., means based on n = 12 or n = 16). Vertical bars are 1 SE of replication means (i.e., n = 4). Symbols in legend, source of variance, and results from ANOVA are the same as described in Fig. 1. Note that the y axis scale for (a, b) predawn and (e, f) sunset are the same, but the scale for (c, d) midday is double that of predawn and sunset. The above illustration was derived from measurements of as many as 2304 leaves.
