*3.1. Establishment of SSC Detection Model for Fresh Jujubes in Open-Field Cultivation*

3.1.1. SSC Detection Models Using Full Wavelengths

Open-field cultivation is the main mode in the planting of jujube. The spectral information of the open-field cultivation samples was pre-processed using baseline and SG. Based on the spectrum with no-pretreatment and pretreatment, LS-SVM models of the SSC were established, and fresh jujubes from two cultivation modes were predicted. The prediction results are shown in Table 3.


**Table 3.** Prediction results of SSC using different pre-processing methods.

In Table 3, when built models with the samples cultivated in the open field were used to predict the samples of the same cultivation methods, results of no-pretreatment and SG pretreatment were similar (Rp2 = 0.80, RMSEP = 1.14%, RPD = 2.25) and better than the results of baseline. The prediction ability of the three methods for rain-shelter samples was not ideal (Rp2 = 0.47~0.59, RMSEP = 2.54~2.77%, RPD = 1.03~1.12), which indicated that the sharing ability of the model needs to be improved. On the whole, compared with the results of baseline and SG, the prediction ability of the constructed model with no-pretreatment was better. Therefore, spectral data without preprocessing were used for analysis in the following study.
