连续投影算法在油菜叶片氨基酸总量无损检测中的应用

Application of Successive Projections Algorithm to Nondestructive Determination of Total Amino Acids in Oilseed Rape Leaves

应用近红外光谱技术结合连续投影算法(SPA)实现了油菜叶片氨基酸总量(TAA)的快速无损检测。对150个油菜样本进行光谱扫描,通过比较不同预处理,建立油菜叶片氨基酸总量预测的最优偏最小二乘法(PLS)模型。同时应用SPA提取有效波长,作为多元线性回归(MLR),PLS和最小二乘-支持向量机(LS-SVM)的输入变量,分别建立SPA-MLR,SPA-PLS和SPA-LS-SVM模型。以决定系数(R2)和均方根误差(RMSE)作为模型评价指标。结果表明,SPA-MLR和SPA-PLS均优于全波段的PLS模型,SPA-LS-SVM获得了最优的预测结果,其预测的R2和RMSEP分别为0.9830和0.3964,获得了满意的预测精度。说明应用光谱技术检测油菜叶片TAA是可行的,并能获得满意的预测精度,为进一步应用光谱技术进行油菜生长对逆境胁迫的反应及大田监测提供了新的方法。

Near infrared （NIR） spectroscopy combined with successive projections algorithm （SPA） was investigated for the fast and nondestructive determination of total amino acids （TAA） in oilseed rape leaves. Total amino acids are important indices of the growing status of oilseed rape. A total of 150 leave samples were scanned,the calibration set was composed of 80 samples,the validation set was composed of 40 samples and the prediction set was composed of 30 samples. The optimal partial least squares （PLS） model was developed for the prediction of total amino acids in oil seed rape leaves after the performance comparison of different pretreatments,including smoothing method,standard normal variate （SNV）,the first derivative and second derivative. Simultaneously,successive projections algorithm was applied for the extraction of effective wavelengths （EWs）,which were thought to have least collinearity and redundancies in the spectral data. The selected effective wavelengths were used as the inputs of multiple linear regression （MLR）,partial least squares （PLS） and least square-support vector machine （LS-SVM）. Then the SPA-MLR,SPA-PLS and SPA-LS-SVM models were developed for performance comparison. The determination coefficient （R^2） and root mean square error （RMSE） were used as the model evaluation indices. The results indicated that both SPA-MLR and SPA-PLS models were better than full-spectrum PLS model,and the best performance was achieved by SPA-LS-SVM model with R^2=0.983 0 and RMSEP=0.396 4. An excellent prediction precision was achieved. In conclusion,successive projections algorithm is a powerful way for effective wavelength selection,and it is feasible to determine the total amino acids in oilseed rape leaves using near infrared spectroscopy and SPA-LS-SVM,and an excellent prediction precision was obtained. This study supplied a new and alternative approach to the further application of near infrared spectroscopy in the response of stress and on-field monitoring of the growing oilseed rape.