Spectral vegetation indices have proved versatile for rapid, non-destructive estimation of different canopy parameters. A combination of the canopy chlorophyll content index (CCCI) and the canopy nitrogen index (CNI) was used in previous studies to predict the canopy nitrogen (N) status of wheat until the end of stem elongation (Zadoks stage 13–37). The objective of this study was to evaluate and extend the CCCI-CNI approach to the end of booting (Zadoks 49) for winter wheat grown in temperate, high-yielding regions of Austria, where growing conditions, management practices, and N fertilization windows differ from the semi-arid cropping systems where the indices were developed. A comprehensive data set consisting of a time series of crop biomass, N concentration (%N), and spectral reflection measurements from three field experiment conducted during the growing seasons 2017/18, 2018/2019, 2019/20 with four winter wheat cultivars grown under four different N fertilisation levels in Tulln, Austria, was used for this study. While prediction of crop %N and N content (N_cont) using the original parameter values was not satisfactory, modification of the regression model between CCCI and CNI resulted in a skilful prediction of a broad range of %N and N_cont, with R² values of 0.81 (RMSE = 0.72 %) and 0.96 (RMSE = 0.83 g m⁻²) for %N and N_cont, respectively. The results indicate that CCCI-CNI is a promising index for estimating N_cont of winter wheat of Austrian winter wheat until Zadoks stage 49, i.e. the end of the time when farmers make decisions about top dress N fertilization.

光谱植被指数已被证明可用于快速、无损地估计不同冠层参数。之前的研究中使用冠层叶绿素含量指数 (CCCI) 和冠层氮指数 (CNI) 的组合来预测小麦的冠层氮 (N) 状态，直到茎伸长结束（Zadoks 阶段 13-37）。本研究的目的是评估 CCCI-CNI 方法并将其扩展到孕穗结束 (Zadoks 49) 的奥地利温带高产地区的冬小麦，这些地区的生长条件、管理实践和施氮窗口不同来自制定指数的半干旱种植系统。由作物生物量、氮浓度 (%N) 的时间序列组成的综合数据集，本研究使用了在 2017/18、2018/2019 和 2019/20 生长季节进行的三个田间试验的光谱反射测量，这些试验在奥地利图尔恩的四种不同施氮水平下种植的四个冬小麦品种。而预测作物%N和N含量（N_cont ) 使用原始参数值并不令人满意，CCCI 和 CNI 之间的回归模型的修改导致对 %N 和 N _cont的广泛范围的巧妙预测，R ²值为 0.81 (RMSE = 0.72 %) 和 0.96 (RMSE = 0.83 gm ^-2 ) 分别为 %N 和 N _cont。结果表明，CCCI-CNI是估计N A看好指数_续奥冬小麦冬小麦直到Zadoks阶段49，即当农民做出顶级礼服施氮决定的时候结束。