油菜氮素光谱定量分析中水分胁迫与光照影响及修正

Effect and Correction of Water Stress and Lighting Factor on Rape Nitrogen Content Spectral Analysis

研究了油菜氮素和水分胁迫在光谱检测中的相互作用,以及光照的变化对作物光谱检测的影响。为了克服光照因素对光谱检测的影响,针对氮素和水分的特征波长分别建立了基于光谱反射率变化率的光照修正模型;为了实现对氮素和水分相互作用的解耦,针对不同含水率水平的植株分别建立了全氮含量光谱特征的主成分回归模型。利用氮素光谱组合分析模型对植株全氮含量进行预测,结果表明,实测值与预测值的相关系数R为0.92,均方根误差(RMSE)为0.53,优于前期采用6特征波长变量和主成分回归法所建立的预测模型。

The interaction between rape nitrogen content and water status and influencing factor of lighting in spectrum analysis were developed. In order to avoid the effect of lighting fluctuation, the correction models which based on variation ratio of spectral reflectance were established in each spectral characteristic wavelength of rape nitrogen content and moisture content. The method of principal component analysis （PCA） was used to establish the nitrogen spectral predictive model under different moisture content levels in order to avoid the interaction between rape nitrogen and water status. The combination model was used to predict the nitrogen content of rape. The result showed that the correlation coefficient between the estimated values and the real values is 0.92, the root mean square error is 0.53. The precision of combination model is higher than the previous model which used PCA method and 6 wavelength variables.