A simulation model for predicting canopy structure and light distribution in wheat

Abstract

Quantitative simulation of architectural structure and light distribution within a crop canopy is important for photosynthesis estimation and virtual construction. This study was undertaken to simulate the leaf curve, canopy structure and light distribution in winter wheat (Triticum aestivum L.). The field experiments with different plant types and sowing densities were carried out, and the time-course changes in canopy structure and light distribution were measured in winter wheat. The leaf curvature in wheat canopy increased with increasing sowing density and the leaf curve could be simulated with a quadratic function and its varied forms. The maximal value of leaf curvature was considered as a cultivar parameter reflecting the genetic characteristics, and the plant number per unit area was used to quantify the effects of sowing density on leaf curvature. Based on the simulated canopy structure, the leaf angle distribution function (f(θL)), extinction coefficient (K(θ)) and leaf area index (LAI) of the canopy were directly calculated by dividing leaf inclination angle into tiny units and accumulating the corresponding leaf areas. Then, the vertical distribution of photosynthetic photon flux density (PPFD) in a canopy could be simulated by using the Beer’s law. The models were validated with the independent dataset from the field experiment of different wheat cultivars. The average relative root mean square error (RRMSE) between the estimated and observed values were 17.44% for layered LAI and 19.35% for PPFD. These results indicated that the present model could effectively predict the growth dynamics of structure and of light distribution within wheat canopies, which would be useful for structural visualization or photosynthesis simulation.