*3.1. Screening of Near-Infrared Hyperspectral Characteristic Bands*

Figure 7 shows the selected frequency of each variable of the tomato leaf mildew samples. The variables that were selected more than 35 times became the final selected variables, and GA greatly reduced the number of variables from hundreds to only several. The GA operation screened eight near-infrared hyper-spectral characteristic wavebands of tomato leaf mildew samples, which corresponded to 1016 nm, 1019.9 nm, 1157.1 nm, 1160.5 nm, 1163.9 nm, 1338.7 nm, 1553.3 nm, and 1556.7 nm, respectively.
