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Keywords:

  • Alocasia macrorrhiza;
  • cost/benefit analysis;
  • light acclimation;
  • modelling;
  • photosynthesis

ABSTRACT

A whole-plant carbon balance model incorporating a light acclimation response was developed for Alocasia macrorrhiza based on empirical data and the current understanding of light acclimation in this species. The model was used to predict the relative growth rate (RGR) for plants that acclimated to photon flux density (PFD) by changing their leaf type, and for plants that produced only sun or shade leaves regardless of PFD. The predicted RGR was substantially higher for plants with shade leaves than for those with sun leaves at low PFD. However, the predicted RGR was not higher, and in fact was slightly lower, for plants with sun leaves than for those with shade leaves at high PFD. The decreased leaf area ratios (LARs) of the plants with sun leaves counteracted their higher photosynthetic capacities per unit leaf area (Amax). The model was manipulated by changing parameters to examine the sensitivity of RGR to variation in single factors. Overall, RGR was most sensitive to LAR and showed relatively little sensitivity to variation in Amax or maintenance respiration. Similarly, RGR was relatively insensitive to increases in leaf life-span beyond those observed. Respiration affected RGR only at low PFD, whereas Amax was moderately important only at high PFD.