基于PROSAIL模型的夏玉米叶绿素含量垂直分层模拟

为了给精准施肥灌溉及病虫害防治等提供基础数据支撑,开展以作物垂直分层叶绿素监测的模拟研究.于2019—2020年进行了不同施氮水平下夏玉米叶绿素含量与光谱反射率监测试验,并模拟了夏玉米叶绿素含量垂直分层规律.结果表明:夏玉米的叶绿素含量随着冠层深度的增加呈侧放的铃型;利用叶绿素最敏感波段699~722 nm的反射率构建夏玉米叶绿素模拟代价函数,实现了基于PROSAIL的夏玉米叶绿素含量垂直分层模拟;综合分析不同生育期各层叶绿素的估算精度,在平均叶绿素模拟相对误差RE控制在45%范围内基础上,进一步厘清了夏玉米叶绿素垂直分层模拟效果,即第1层叶片在抽雄期与灌浆期、其他层在全生育期模拟的决定系数R²在0.114 5~0.799 3,均方根误差RMSE在2.41~12.13 μg/cm²,相对误差在9.67%~98.22%.相关研究结果可为作物叶绿素垂直分层模拟应用提供理论与技术支持.

Vertical stratified simulation of chlorophyll content of summer maize based on PROSAIL model

Simulation research on crop vertical layered chlorophyll monitoring was made to provide ba-sic data support for precision fertilization, irrigation and pest control. Summer maize chlorophyll and spectral reflection monitoring tests were carried out at different nitrogen application levels from 2019 to 2020, and the vertical stratified law of summer maize chlorophyll content was simulated. The results show that the chlorophyll content of summer maize shows a lateral bell shape as the canopy depth increases;the reflectance that the most sensitive band of chlorophyll is 699-722 nm was used to construct the summer maize chlorophyll simulation cost function, realizing the vertical stratification simulation of chlorophyll content in summer maize based on PROSAIL. Based on the comprehensive analysis of the estimation accuracy of chlorophyll in each layer at different growth stages, the simulation effect of vertical stratification of chlorophyll in summer maize was further clarified on the basis of controlling the re-lative error RE of average chlorophyll simulation within 45%, that is, the determinant coefficient R² of the first layer of leaves during the tasseling and filling stage and the other layers in the whole fertility simulation is in the range of 0.114 5-0.799 3, the root mean square error RMSE is in the range of 2.41-12.13 μg/cm² and the relative error RE is in the range of 9.67%-98.22%. The relevant research results can provide theoretical and technical support for the vertical stratified simulation application of crop chlorophyll.