Table 1.
Parameters on photosynthesis, respiration, and tissue nitrogen content.
Figure 1.
Relationship between leaf nitrogen content per area (Narea) and light-photosynthesis curve parameters.
Each point was obtained from sun leaves (white circles) and shade leaves (black circles) of Morus bombycis. Maximum photosynthetic rate (A), initial slope of the curve (B), convexity of the curve (C), and dark respiration rate at 25°C (D). See text for the expressions for (A) and (B) and the constants for (C) and (D).
Figure 2.
Estimated net assimilation rate (NAR) as a function of leaf nitrogen content per area (Narea).
Solid lines and dashed lines represent NAR in 100% photosynthetic photon flux density (RPPFD) and 10% RPPFD, respectively. The thick lines and the thin lines represent Morus bombycis, Acer buergerianum, respectively.
Table 2.
Morphological and physiological parameters for material species.
Figure 3.
Changes in the relative growth rate (RGR) with increasing leaf nitrogen content (Narea) when SAR was changed.
(A) 100% photosynthetic photon flux density (100%RPPFD). (B) 10%RPPFD. Each line is labelled with a number denoting nitrogen absorption rates per unit root mass (SAR). Values obtained from Morus bombycis were used (Table 2).
Figure 4.
Effects of the leaf-to-root ratio (L/R) on relative growth rate (RGR) and leaf nitrogen content (Narea).
(A) 100% photosynthetic photon flux density (100%RPPFD). (B) 10%RPPFD. Solid lines represent RGR and dashed lines represent Narea, respectively. Thick lines represent nitrogen absorption rates per unit root mass (SAR) = 0.005 and thin lines represent SAR = 0.0005. Black circles represent the maximum relative growth rate (RGR) and white circles represent the associated Narea. Parameter values obtained from Morus Bombycis were used (Table 2).
Figure 5.
Optimal leaf-to-root ratio (L/R) and optimal leaf nitrogen content (Narea).
Thick lines represent 100% photosynthetic photon flux density (100%RPPFD) and thin lines represent 10%RPPFD. Solid lines represent optimal L/R and dashed lines represent optimal Narea, respectively.
Figure 6.
Optimal and observed leaf to root ratio (L/R) and leaf nitrogen content (Narea) for each light and nitrogen availabilities.
(A,B) Values of Morus bombycis. (C,D) Values of Acer buergerianum. White squares indicate optimal values, and white and black circles indicate observed values in high-light and low-light environments, respectively. Dashed lines are ranges of values covering 98% of the optimum. Treatment groups were high-light condition and nitrogen-rich (HR) or nitrogen-poor (HP), and shade condition and nitrogen-rich (SR) or nitrogen-poor (SP).