*2.3. Statistical Data Analysis*

The Shapiro–Wilk test was used to verify the normality of the data related to the biophysical parameters. The ANOVA method was applied to determine the difference among the three treatments (control, stress, and bacteria groups), while the mean difference was verified using the Tukey test. A 95% confidence interval was then adopted for all statistical analyses. For spectral response curves, the correlation of single wavelengths with the selected biophysical parameters was calculated for both reflectance and absorbance values. Contour maps resulting from traditional 2D correlation analysis were also applied between the pairs of the treatments to determine the spectral intervals that presented similarity. Correlation graphs between the biophysical parameters and all the spectral wavelengths of the three groups were then plotted. The results were compared using their means, standard deviations, correlation coefficient, coefficient of regression (R2), mean discrepancy (by bootstrapping), and root mean squared error (RMSE). The metrics evaluated here were obtained with the open-source software PAST v. 3.2 and the statistical program R v. 3.6.
