【摘要】 为了利用高光谱技术准确探测作物氮素营养状况,以东北春玉米为研究对象,获取6个氮肥梯度的随机试验数据,并采用无人机(unmanned aerial vehicle, UAV)搭载UHD185高光谱成像系统,获取关键生育期试验小区内春玉米冠层高光谱遥感影像,通过5种方法对提取的冠层高光谱信息进行预处理,并分别采用偏最小二乘回归、BP神经网络回归和随机森林回归3种算法,构建春玉米氮营养指数反演模型。结果表明:(1)各光谱预处理下,春玉米氮营养指数与冠层高光谱反射率在近红外波段范围内相关性较高;比较高光谱特征参数,春玉米氮营养指数与黄边内一阶微分光谱中的最大值相关性较高;(2)经MSC预处理后,以高光谱特征参数为变量构建的反演模型精度最高,预测集R~2的平均值为0.80;(3)随机森林算法结合MSC预处理反演玉米氮营养指数效果更好,精度更高,模型更稳定。通过对比不同方法建立的春玉米氮营养指数反演模型,提高了模型估测能力和验证精度,有利于模型估测能力的调控与优化,提升了反演模型的适用性,为春玉米精准氮营养诊断和精准氮肥管理提供了理论依据和技术支撑。更多还原

【Abstract】 Hyperspectral technology can accurately detect the status of crop nitrogen nutrition.Taking the Northeast spring corn as the sample, the random test data of 6 nitrogen fertilizer gradients were obtained, using UHD 185 hyperspectral imaging system, the hyperspectral remote sensing images of spring maize canopy in the experimental plot of key growth period were obtained, and the extracted hyperspectral information of canopy was preprocessed by five methods.The inversion model of nitrogen nutrition index of spring maize was constructed by using partial least squares regression, BP neural network and random forest algorithm.The conclusions were as follows:(1)In the Near-infrared band, the hyperspectral reflectivity had high correlation with agronomic parameters under different preprocessing methods.Above ground biomass and nitrogen nutrition index were highly correlated with spectral reflectance and characteristic parameters.(2)The model was constructed with SMC pretreated by hyperspectral characteristic parameters.The average R~2 of the prediction set reached 0.80,which was higher than other preprocessing methods.(3)The random forest algorithm combined with the MSC pre-processing method to invert the nitrogen nutrition index of corn had better effect, higher accuracy, and more stable model.In this study, by comparing the diagnostic model of spring maize nitrogen nutrition established by different methods, it ensured the rapidity, accuracy and standardization of the inversion of maize nitrogen nutrition were ensured, which laid the technical foundation and theoretical basis for precise fertilization of maize.更多还原