Study on the Quick Non-Destructive Detection of Citrus Huanglongbing Based on the Spectrometry of VIS and NIR

Huanglongbing (HLB) is a devastating disease of citrus fruit trees, which is very harmful to citrus industry. Based on the theory of model averaging, the feasibility of improving the accuracy of quick and non-destructive detection of citrus HLB was studied using the visible and near infrared spectrum technique. The visible and near infrared spectra of citrus leaves were collected and record, and three kinds of leaves with slight HLB, moderate HLB, serious HLB was identied using real time fluorescent quantitative PCR and nutrient deficiency and normal was identified by PCR also, in all five types. Three kinds of different strategies, including the spectra directly stitched, the normalized spectral stitched and model averaging were as basis, combined with partial least squares discriminant analysis (PLS-DA) and multiple linear regression (MLR) method, and the non-destructive detection Spectrometry model of citrus HLB were developed using visible and near infrared spectroscopy respectively. By comparison, it can be found that the detection accuracy of Spectrometry model was higher than visible or near infrared spectroscopy single detection model while the detection accuracy of spectra directly stitched PLS-DA model was highest after derivative preprocessing. The correlation coefficient (Re) of the model was 0.97, the root mean square error (RMSEP) 0.67, and the total mid judgement rate 3%. The reason was to eliminate baseline drift of spectra. The detection accuracy of spectra directly stitched PLS-DA model after normalized was second, and the total midjudgement rate was 7%. The detection accuracy of visible and near infrared average model was lowest, and the total midjudgement rate was 7.2%. The experimental resultsshowed that using visible and near infrared spectroscopy combined with spectra stitched method can improved the detection accuracy of non-destructive detection model of Citrus HLB, and the research can provide a reference for other areas of the Spectrometry.