Reflectance estimation of canopy nitrogen content in winter wheat using optimised hyperspectral spectral indices and partial least squares regression
Reflectance estimation of canopy nitrogen content in winter wheat using optimised hyperspectral spectral indices and partial least squares regression
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DOI：
10.1016/j.eja.2013.09.006
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发表时间：
2014-01-01
影响因子：
5.2
通讯作者：
Schmidhalter, Urs
中科院分区：
文献类型：
--
作者：
Li, Fei;Mistele, Bodo;Schmidhalter, Urs
基于不同的算法，已经提出了许多光谱指数来获得植物氮（N）营养指标。然而，关系。所选光谱指数与作物冠层氮含量之间的关系往往不一致。本研究的目的是测试光谱指数和偏最小二乘回归（PLSR）的性能，并比较它们用于预测冬小麦冠层氮含量。本研究在凉爽湿润的德国东南部和炎热干燥的华北平原进行了三个冬小麦生长季的研究。德国冬小麦冠层氮含量在0.54%~ 5.55%之间，中国冬小麦冠层氮含量在0.57%~ 4.84%之间，随生育期和年份的不同而变化。表现最好的光谱指数和波段组合不同的生长阶段，品种，网站和年。与性能最好的光谱指数相比，PLSR模型的R-2的平均值增加了76.8%和75.5%，分别在校准和验证数据集。结果表明，当冠层反射率数据包含在校正模型中时，PLSR是一种潜在的有用方法，可以在田间条件下获得不同生育期、品种、地点和年份的冬小麦冠层氮含量。偏最小二乘回归分析可用于实时评估田间冬小麦氮素状况，指导农民准确施用氮肥。(C)2013爱思唯尔有限公司版权所有。
Many spectral indices have been proposed to derive plant nitrogen (N) nutrient indicators based on different algorithms. However, the relationships. between selected spectral indices and the canopy N content of crops are often inconsistent. The goals of this study were to test the performance of spectral indices and partial least square regression (PLSR) and to compare their use for predicting canopy N content of winter wheat. The study was conducted in cool and wet southeastern Germany and the hot and dry North China Plain for three winter wheat growing seasons. The canopy N content of winter wheat varied from 0.54% to 5.55% in German cultivars and from 0.57% to 4.84% in Chinese cultivars across growth stages and years. The best performing spectral indices and their band combinations varied across growth stages, cultivars, sites and years. Compared with the best performing spectral indices, the average value of the R-2 for the PLSR models increased by 76.8% and 75.5% in the calibration and validation datasets, respectively. The results indicate that PLSR is a potentially useful approach to derive canopy N content of winter wheat across growth stages, cultivars, sites and years under field conditions when a broad set of canopy reflectance data are included in the calibration models. PLSR will be useful for real-time estimation of N status of winter wheat in the fields and for guiding farmers in the accurate application of their N fertilisation strategies. (C) 2013 Elsevier B.V. All rights reserved.