Quantification of light absorption and photosynthesis of tobacco canopy using 3-D modeling

Plant architecture is one of the determinants on canopy light absorption and photosynthesis. The quantification of architecture is rather difficult for some specific crops, i.e. tobacco. In this study, a field experiment was carried out to study the architecture of two tobacco cultivars (Y87 and K326) in situ by the combination of 3-D laser scanning and digitizing methods at the squaring stage. Static 3-D model of tobacco plant was built based on leaf surface geometry (collected by 3-D scanning) and leaf outline (obtained by digitizing in situ). The parameters describing plant architecture were derived and light absorption and potential photosynthesis of individual leaves as well as plants were calculated utilizing 3-D modeling. The validation results indicated that the canopy light distribution can be computed rather accurately comparing with the field measurements. Simulation results showed light absorption and potential photosynthesis of Y87 were lower than those of K326, partly because the leaf area of individual Y87 plants was smaller than that of K326.