A Dynamic L-System-Based Architectural Maize Model for 3-D Radiative Transfer Simulation

We integrate the time series simulation capability of the maize model within an extended L-system (ELSYS) using the growth equations from a 4-D maize and a leaf breakpoint model. These models simulate maize growth from emergence to male anthesis, accounting for 3-D architecture during the vegetative season. We employ two methods to achieve time series simulation in ELSYS: directly use the growth equations in the 4-D maize and leaf breakpoint models, and name ELSYS coupling 4-D maize (ELSYS4Dmaize). Alternatively, replace the stem radius-leaf order function with a stem radius-height function and employ linear interpolation to transform the leaf width-length ratio from a constant value to a function that varies with leaf order, thereby simulating a 4-D maize structure, and name the dynamic L-system-based architectural maize (DLAmaize) model. The DLAmaize model is applied to maize canopy reflectance simulations using the discrete anisotropic radiative transfer (DART) model and radiosity-graphics combined method (RGM), along with a comparison with the 1-D scattering by arbitrarily inclined leaves (SAIL) model. The simulated reflectance of maize canopy from ELSYS4Dmaize and DLAmaize differs significantly in the hotspot direction (the absolute value of the relative difference can be up to 67.4%). In addition, comparisons among RT models show that the DART model and RGM simulate close reflectances. The SAIL model yields significant differences (e.g., the absolute value of the relative difference can be up to 41.16% in the nadir direction) owing to its assumption of the homogeneous canopy. DLAmaize enhances remote sensing of dynamic 4-D vegetation canopies modeling and holds promise for remote sensing applications.