Figure 1. (a)Time course of plant mass following growth in an exponential, an expolinear or sigmoidal way. The curves are hypothetical examples, for which the mass after 40 days is set to 100%. (b) Time course of RGR for different species grown in conditions of unlimited water and nutrient supply (Arabidopsis thaliana (unpublished data from D. Tholen), Holcus lanatus, Deschampsia flexuosa). Day 0 indicates the first harvest of the seedlings.

Figure 2. Growth response coefficients (GRC) for the C-budget variables that underlie interspecific variation in relative growth rate (RGR). Each GRC value indicates to what extent a change in the parameters of eqns [2] and [3] scales with the relative change in RGR. Data in (a) are for measured growth parameters, data in (b) for the factors underlying unit leaf rate (ULR). Derived from Poorter et al. (1990). SLA, specific leaf area; LMF, leaf mass fraction; PS_A, daily whole plant photosynthesis per unit leaf area; FCI, fraction of daily fixed carbon that is incorporated in the plant; [C], carbon concentration.

Figure 3. Carbon budgets of plants grown under various environmental conditions. The upper left panel indicates what fraction of the daily fixed C is spent in shoot (ShR) and root respiration (RR), and what fraction is used for growth (FCI), for a plant grown at a daily quantum input of 16 mol m^–2 day^–1, a  CO₂ concentration of 350 L L^–1 and an unlimited nutrient and water supply (hydroponics). The other three panels indicate how the carbon budget changes in plants grown with less light (8 mol m^–2 day^–1), a higher  CO₂ concentration (700 L L^–1) or a lower N supply. Data based on various observations for Holcus lanatus and Plantago major.

Figure 4. Summary of growth response coefficient (GRC) data for plants that differed in growth due to differences in light,  CO₂, nutrients, water or salt. (a) GRC values for unit leaf rate (ULR); (b) specific leaf area (SLA); (c) leaf mass fraction (LMF). Data are averages from a meta-analysis for the factors light (n = 71),  CO₂ (n = 113), nutrients (n = 75) and water (n = 15) (for more information see Poorter and Nagel, 2000), as well as 15 experiments on salt stressed plants. Note that a positive GRC indicates that an increase in RGR goes with an increase in a given parameter, and a decrease in RGR with a decrease in that parameter.

Figure 5. Diagram showing differences between plants that are inherently fast- and slow-growing. Red lines indicate variables with highest values for low-SLA plants, blue lines indicate variables with highest values for high-SLA plants.