Fig. 5.
Effects of photosynthetic nitrogen (Nph) distributions with different values of fd (Fig. 4) on daily canopy carbon assimilation (DCA) under different daily photosynthetic photon integrals (DPI, mol photons m−2 d−1) relative to average DPI during acclimation (aDPI). (A) Two-fold aDPI (aDPI200); (B) aDPI (aDPI100); (C) half aDPI (aDPI200). Acropetal Nph reallocation increases with fd. Plants grown under high nitrogen and high light (HN+HL, orange open circles), under high nitrogen and low light (HN+LL, black closed circles), under low nitrogen and high light (LN+HL, orange open triangles), and under low nitrogen and low light (LN+LL, black closed triangles) are compared under given DPI. The relative change in DCA was calculated by dividing the DCA obtained with a given Nph distribution by the DCA obtained with the control Nph distribution (fd=1) under same DPI. A change within ±5% (grey shading) is considered insignificant.