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Fig. 10. Absolute mean leaf net assimilation rate (A) (left-most y axis) in response to diurnal course of incident photosynthetic photon flux density (PPFD) during inflorescence emergence on day after 50% emergence (DAE) 81 during the 1994 growing season (replotted from Fig. 6h). The season-long mean leaf net assimilation rate (AN) was normalized to a relative scale between 0 and 1 by dividing each value of A, obtained per sample interval, by the daily maximum (Amax) leaf net assimilation rate (i.e., AN = A/Amax) across all treatments, for both years, and all development stages except for soft and hard-dough (replotted from Fig. 6a–d and f–i). On the second y axis (right-most y axis), the resultant values of AN were plotted in response to the diurnal course of (b) PPFD. Arrows denote direction of hysteresis loop from dawn (DW), after dawn (AD), early morning (EM), midmorning (MM), midday (MD), midafternoon (MA), late-afternoon (LA), predusk (PD), and dusk (DK). Symbol legend same as given in Fig. 1a. Open-circle symbol with two-way error bars denote the pooled SE across all sample intervals for the A (vertical) and PPFD (horizontal) parameters. The single diurnal course illustrated above in panel (a) was derived from measurements of as many as 360 leaves, whereas the normalized response was derived from measurements of as many as 3180 leaves.
