Response of different varieties of maize to nitrogen stress and diagnosis of leaf nitrogen using hyperspectral data

Spectral technology is theoretically effective in diagnosing N stress in maize (Zea mays L.), but its application is affected by varietal differences. In this study, the responses to N stress, leaf N spectral diagnostic models and the differences between two maize varieties were analysed. The variety "Jiyu 5817" exhibited a greater response to different N stresses at the 12-leaf stage (V12), while "Zhengdan 958" displayed a greater response in the silking stage (R1). Correlation analysis showed that the spectral bands more sensitive to leaf N content were 548-556 nm and 706-721 nm at the V12 stage in "Jiyu 5817" and 760-1142 nm at the R1 stage in "Zhengdan 958". An N spectral diagnostic model that considers the varietal effect improves the model fit and root mean square error (RMSE) with respect to the model without it by 10.6% and 29.2%, respectively. It was concluded that the V12 stage for "Jiyu 5817" and the R1 stage for "Zhengdan 958" were the best diagnostic stages and were more sensitive to N stress, which can further guide fertilization decision-making in precision fertilization.