锦橙叶片钾含量光谱监测模型研究

【目的】快速、无损、准确地获取柑橘叶片营养信息。【方法】以盆栽蓬安100锦橙为试材,通过精确控制施肥处理(K0:0g,K1:30g,K2:75g,K3:90,K4:120gk2O/株/年),利用鲜叶进行光谱检测钾素营养状况分析。【结果】可见近红外波段范围内,各施钾处理蓬安100锦橙夏梢叶片光谱反射强度呈K3K0K1K2K4趋势。通过对反射光谱、一阶微分、二阶微分和倒数对数光谱进行多元散射(multiple scattering correction,MSC)校正处理,运用偏最小二乘法(partial least square method,PLS)与内部交叉验证建立了钾含量预测回归模型,其中反射光谱的二阶微分光谱钾含量定标模型具有最好的预测能力,其预测相关系数最大,r=0.82;预测均方根误差较小,RMSEP=0.0038;偏差(Bias)绝对值最小,Bias=-2.34E-05。【结论】通过锦橙叶片反射光谱二阶微分值与叶片钾含量构建的PLS回归模型,可以较好地预测蓬安100锦橙夏梢叶片钾含量。进一步分析表明,波段477—515nm、541—588nm、632—669nm、701—718nm和754—794nm是反射光谱二阶微分与蓬安100锦橙叶片钾含量定标模型的特征波长。

A Spectrum Based Models for Monitoring Leaf Potassium Content of Citrus sinensis (L)cv.Jincheng Orange

Objective]Method]Field experiments were conducted to assess the potassium content in leaves of Citrus sinensis(L)cv.Peng'an 100 Jincheng orange by using VIS/NIRS spectral method.Before calibration, principal component analysis (PCA)and partial least square(PLS)techniques were applied in data pre-processing.Result]The order of leaf reflective spectrum intensity was K_3＞K_0＞K_1＞K_2＞K_4 in the visible near-infrared range of 400-1000 nm, where the K fertilizer usage of K_0, K_1, K_2, K_3,K_4 treatments were 0 g, 30 g, 75 g, 90 g, 120 g(K_2O/plan/year), respectively.The calibration models of potassium content were built by applying PLS and internal cross-validation test method and through processing the reflectance spectrum, the first derivatives, the second derivatives and the reciprocal logarithm spectrum of Peng'an 100 Jincheng leaves using multiplicative scatter correction(MSC).The results showed that the model of the second derivatives calibration of reflectance spectrum had the best predicative ability, the highest correlation coefficient, the smallest root mean square error of predictation(RMSEP)and the smallest absolute bias at 0.82, 0.0038 and -2.34E-05, respectively.Conclusion]The second derivatives of reflectance spectrum could be used to predict the potassium content in Peng'an 100 Jincheng leaves.And 477-515 rim, 541-588 rim, 632-669 nm, 701-718 nm and 754-794 nm were the characteristics of wavelengths of second derivatives of reflectance spectrum predicting potassium content in summer shoot leaves of of Peng'an 100 Jincheng.