## 2 Materials and Methods
### Vis/NIR SMI System  
The major components of the newly developed SMI system were an SMI camera (OCI-D2000; Bayspec Inc., San Jose, CA, USA) with 38 wavelengths, a spectral range of 462-870 nm with a full width at half maximum spectral resolution between 12-15 nm, an objective lens (focal length 35 mm), 10 halogen light bulbs (41,870 WFL 12 V 50 W MR16; Osram, Munich, Germany) for illumination, and commercial software provided by Bayspec Inc., which is intended for pixel image acquisition. The SMI camera consists of two cameras,one camera can measure a wavelength range of 462 nm-623 nm, and the other camera can measure a wavelength range of 631 nm-870 nm. The system is illustrated in Figure 1.  
The total number of image pixels in the SMI camera was 2048 \(\times\) 1088 pixels. Halogen lamps were selected because they emit a continuous spectrum of light from near-ultraviolet to deep infrared. Cooling fans were installed at the end of the halogen lamps for ventilation because of the high radiant energy produced by the illumination during the imaging process. When taking the sample images, the exposure time was optimized using the auto exposure time function provided by commercial software (BaySpec SpecFrabber; BaySpec Inc., CA, USA) to avoid saturation of the pixel intensity. The commercial software acquired the spectral data of sample images in the form of a 3D spectral data cube consisting of two spatial dimensions (x- and y-directions) and a single spectral (\(\lambda\)) dimension. The dimensions of the spectral data cube were 400 pixels in the x-direction, 200 pixels in the y-direction, and 38 bands (wavelength) in the \(\lambda\)-direction. The number of visible and NIR bands used was 16 and 22, respectively. In addition, sample images were acquired every four days to analyze the heat stress damage during growth.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Temp.** & **Fresh Weight** & **Dry Weight** & **Number of** & **Leaf Area** & **Leaf Length** & **Leaf Width** \\ (\({}^{\circ}\)C) & **(g/Plant)** & **(g/Plant)** & **Leaves (/Plant)** & **(cm2/Plant)** & **(cm/Plant)** & **(cm/Plant)** \\ \hline
20/16 & 334.2 \({}^{\mathrm{N}}\)S & 14.8 \({}^{\mathrm{N}}\)S & 47.0 \({}^{\mathrm{a}}\) & 2974 \({}^{\mathrm{N}}\)S & 32.9 \({}^{\mathrm{N}}\)S & 19.0 \({}^{\mathrm{N}}\)S \\
28/24 & 317.7 \({}^{\mathrm{N}}\)S & 14.7 \({}^{\mathrm{N}}\)S & 42.3 \({}^{\mathrm{a}}\)S & 2925 \({}^{\mathrm{N}}\)S & 32.8 \({}^{\mathrm{N}}\)S & 19.3 \({}^{\mathrm{N}}\)S \\
36/32 & 300.5 \({}^{\mathrm{N}}\)S & 12.7 \({}^{\mathrm{N}}\)S & 40.7 \({}^{\mathrm{b}}\) & 2857 \({}^{\mathrm{N}}\)S & 32.6 \({}^{\mathrm{N}}\)S & 18.0 \({}^{\mathrm{N}}\)S \\ \hline \hline \end{tabular} \({}^{\mathrm{(}}\)S\({}^{\mathrm{(}}\)S\({}^{\mathrm{)}}\) Not statistically significant (not distinguished each other); \({}^{\mathrm{(a-b)}}\) Letters showing statistically significant differences among different groups (Bonferroni correction test).  
\end{table}
Table 1: Average values of major growth parameters of Chinese cabbage grown at 20 \({}^{\circ}\)C, 28 \({}^{\circ}\)C, and 36 \({}^{\circ}\)C for eight days.  
Figure 1: (a) Conceptual diagram of the newly developed visible-near infrared snapshot-based multispectral imaging system and (b) a photo of the experimental setup.