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基于6个小麦品种、5个施氮水平、4年田间试验条件下不同生育时期的小麦叶片高光谱反射率和相应的氮含量及生物量,采用减量精细采样法,系统构建了350～2500nm范围内所有两两波段组成的归一化光谱指数[NDSI(i,j)],综合分析了小麦叶片氮积累量(LNA,gN·m-2)与NDSI(i,j)的定量关系,确定了估算叶片氮积累量的新高光谱特征波段和光谱指数,进而建立了小麦叶片氮积累量监测模型.结果表明:估算小麦叶片氮积累量的敏感波段主要存在于可见光区和近红外区,最佳特征波段组合为720nm和860nm;基于NDSI(860,720)的叶片氮积累量监测模型为LNA=26.34×[NDSI(860,720)]1.887(R2=0.900,SE=1.327).利用独立试验资料的检验结果表明,基于NDSI(860,720)建立的回归模型对小麦叶片氮积累量的估测精度为0.823,RMSE为0.991gN·m-2,模型预测值与观察值之间的符合度较高.可利用新的归一化高光谱参数NDSI(860,720)来估算小麦叶片氮积累量.
Based on 6 wheat cultivars, 5 nitrogen fertilizers, and hyperspectral reflectance and corresponding nitrogen content and biomass of wheat leaves at different growth stages in 4-year field experiment, NDSI (i, j)], a comprehensive analysis of the quantitative relationship between nitrogen accumulation (LNA, gN · m-2) and NDSI (i, j) The new hyperspectral spectral bands and spectral indices for estimating nitrogen accumulation in leaves were determined, and the monitoring model of nitrogen accumulation in wheat leaves was established. The results showed that the sensitive bands of nitrogen accumulation in wheat mainly existed in the visible and near infrared regions, The best combination of characteristic bands was 720 nm and 860 nm, and the N accumulation level of leaf based on NDSI (860 and 720) was LNA = 26.34 × [NDSI (860,720)] 1.887 (R2 = 0.900, SE = 1.327) The results showed that the prediction accuracy of wheat leaf nitrogen accumulation was 0.823 and the RMSE was 0.991gN · m-2 based on the regression model established by NDSI (860,720), and the predicted value of the model was in good agreement with the observation value. Of the normalized hyperspectral parameters NDSI (860,720) Wheat Leaf nitrogen accumulation count.