Abstract
Canopy structural parameters and light radiation are important for evaluating the light use efficiency and grain yield of crops. Their spatial variation within canopies and temporal variation over growth stages could be simulated using dynamic models with strong application and predictability. Based on an optimized canopy structure vertical distribution model and the Beer-Lambert law combined with hyperspectral remote sensing (RS) technology, we established a new dynamic model for simulating leaf area index (LAI), leaf angle (LA) distribution and light radiation at different vertical heights and growth stages. The model was validated by measuring LAI, LA and light radiation in different leaf layers at different growth stages of two different types of rice (Oryza sativa L.), i.e., japonica (Wuxiangjing14) and indica (Shanyou63). The results show that the simulated values were in good agreement with the observed values, with an average RRMSE (relative root mean squared error) between simulated and observed LAI and LA values of 14.75% and 21.78%, respectively. The RRMSE values for simulated photosynthetic active radiation (PAR) transmittance and interception rates were 14.25% and 9.22% for Wuxiangjing14 and 15.71% and 4.40% for Shanyou63, respectively. In addition, the corresponding RRMSE values for red (R), green (G) and blue (B) radiation transmittance and interception rates were 16.34%, 15.96% and 15.36% for Wuxiangjing14 and 5.75%, 8.23% and 5.03% for Shanyou63, respectively. The results indicate that the model performed well for different rice cultivars and under different cultivation conditions.
Highlights
Crop canopy structure depends on the crop’s genetic characteristics and its physiological and biochemical processes, as well as its planting pattern and growth status
The results show that the parameter ELADP could be successfully estimated by the hyperspectral vegetation index
By combining the BeerLambert law and the hyperspectral remote sensing (RS) technique, we developed a dynamic model of the vertical distribution of light in a rice canopy
Summary
Crop canopy structure depends on the crop’s genetic characteristics and its physiological and biochemical processes, as well as its planting pattern and growth status. Canopy structure, which is directly related to the ability of within-canopy light interception, is the most important factor influencing light radiation distribution and light use efficiency [2]. Leaf angle (LA) and leaf area index (LAI) distribution are the principle factors that determine light radiance distribution and leaf physiological characteristic in crop canopies [3,4]. Employing crop varieties with compact plant types is beneficial for improving middle and bottom canopy light conditions, which enhances light use efficiency. Developing quantitative models of crop canopy structure is an important aspect of light energy use and balance research [5,6]
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