Figure 3.

Modeling the effect of predawn NSCs on plant growth. A, Modeling strategy. In the virtual plant, 66% of the carbon is in leaves, 34% in the rest of the plant. Zero percent to 20% of leaf carbon is excess inventory (predawn, NSC), and the rest of the leaf carbon is photosynthetically productive (green). Photosynthetically fixed carbon (PC), from the productive portion of the leaf only, is allocated to the plant in its original proportions, after construction costs are subtracted. Respiratory losses from the roots, and from the leaves at night, are also subtracted. Interest is compounded daily. B, Final weight of plant carbon after 30 d growth, plotted against excess leaf inventory, from 0% to 20% of leaf carbon. The initial weight of plant is 10 mg carbon. The photosynthetic portion of leaf carbon produces either 0.3 or 0.7 g carbon g⁻¹ carbon d⁻¹ (net photosynthesis). Literature values for the percentage of leaf carbon in NSCs at predawn are included on the abscissa for (1) Arabidopsis (Zeeman and ap Rees, 1999), (2) Nicotiana tabacum (Camacho-Cristóbal and González-Fontes, 1999), (3) sugar beet (Fondy and Geiger, 1982), (4) Glycine max (Qiu and Israel, 1992), (5) Acer saccharum (Topa et al., 2001), (6) Ricinus communis (Grimmer et al., 1999), (7) apple (Klages et al., 2001), (8) Populus deltoides (Dickson, 1987), and (9) celery (Davis and Loescher, 1991).