摘要：
With the establishment of the models based on spectral characteristic parameter for estimating foliar nitrogen concentrations ofJuglans regia‘Xinwen 185’, this paper aimed to explore spectral technical approaches to rapidly monitoring the foliar N nutritional status ofJuglans regia ‘Xinwen 185’. Based on the field experiment of fertilizer efficiency, the foliar spectral reflectance and N concentrations of the foliar samples under different amounts of N fertilizer, which were applied in the fruit setting period, the fruit rapid-growth period, the fruit fat-change period and the fruit near-mature period, were measured separately with Unispec-SC and chemical analysis in the laboratory. The Pearson correlation analysis of the foliar spectral reflectance and foliar N element concentrations was done in the 4 phenological periods of fruit development, and the spectral characteristic parameters highly significantly correlated with the foliar spectral reflectance and foliar N element concentration were selected. Finally, the spectral characteristic parameter estimating models of the foliar N element concentration were established by employing regression analysis, with the adopted functions including power function, exponential function, semi-log function, linear function, quadratic function and cubic function, and then the independent sample was used to test the precision of the models, of which the one with the highest fitting degree was screened out. The results indicated that the spectral characteristic parameters, highly significantly correlated with the foliar N element concentration (P<0.01), were reflectance of the green peak position and ratio of red index in fruit setting period, yellow edge position, red valley position, ratio of green index, ratio of red index, normalized difference of green index and normalized difference of red index in the fruit fast-growing period, reflectance of the green peak position and ratio of red index in the fruit fat-change period, and reflectance of the green peak position, he spectra slop of yellow edge and red edge area in the fruit near-mature period. Moreover, the absolute values of the correlation coefficient were all greater than 0.96 in the 4 phenological periods of fruit development. Through cubic function analysis with the reflectance of the green peak position, yellow edge position, ratio of red index and the spectra slop of yellow edge as independent variables, the regression estimation models of the foliar N element concentration in the 4 phenological periods of fruit development were established respectively, and their fitting degreesR2 were all above 0.99. In addition, the predicted values for foliar N concentration ofJuglansregia‘Xinwen185’ were relatively close to measured values, and all the models were examined by the confidence ellipse test; and RMSE and the relative errors (RE) of the independent sample tests were only 0.4533 g/kg and 0.4403%, 0.7716 g/kg and -0.3390%, 0.8793 g/kg and -0.3201%, 0.8145 g/kg and -0.1229% separately in the 4 phenological periods of fruit development. The models showed their significant stability and high estimation accuracy. The findings in this paper manifested that it was feasible to monitor foliar N nutritional levels ofJuglans regia ‘Xinwen 185’ in the 4 phenological periods of fruit development by establishing spectral characteristic parameter models of foliar N element concentration estimation. Spectrum technology possesses great application potential in monitoring N element nutritional status of Juglans regia‘Xinwen 185’.%建立基于光谱特征参量的新温185号（Juglans regia‘Xinwen185’）核桃叶片氮素含量估测模型，旨在为快速监测新温185号核桃叶片N素营养状况提供技术途径。基于肥料效应田间试验，测定N肥不同施用量水平下新温185号核桃果实坐果期、速生生长期、脂化期和近成熟期的叶片光谱反射率和N素含量，采用Pearson相关分析方法筛选与叶片N素含量呈极显著相关的光谱特征参量，并应用回归分析方法建立叶片N素含量光谱特征参量估测模型。结果表明：与叶片N素含量呈极显著相关（P＜0.01）的光谱特征参量在果实坐果期有绿峰反射率和红色比值指数，在果实速生生长期有黄边位置、红谷反射率和绿色比值指数、红色比值指数、绿色归一化差值指数、红色归一化差值指数，在果实脂化期有绿峰反射率和红色比值指数，在果实近成熟期有绿峰反射率、黄边幅值和红边面积。分别以绿峰反射率、黄边位置、红色比值指数和黄边幅值为自变量采用三次函数建立的果实坐果期、速生生长期、脂化期和近成熟期叶片N素含量回归估测模型的拟合度R2均在0.99以上，且模型具有很好的稳定性和很高的估测精度。表明可采用三次函数建立果实不同生育时期叶片N素含量光谱特征参量估测模型对新温185号核桃树体N素营养水平进行监测。光谱技术在核桃树体N素营养信息探测方面有较大的应用潜力。
