## 3 Results
### Remote Sensing Responses
Highest correlations were shown for maize g\({}_{\rm{s}}\) and T\({}_{\rm{r}}\) compared to all the structural indices in the following order rNDVI, OSAVI, NDVI, EVI, and REIP. Photosynthetic efficiency indices such as sPRI and PRI\({}_{\rm{(570^{-}515)}}\); and some VIs associated to pigments like TCARI, PSNDC, and mARI also presented correlations with similar order of magnitude (R\({}^{2}\) between 0.3 and 0.45 with \(p\)-value \(<\) 0.01) (Figure 6 and Figure S4). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Crop** & \multicolumn{3}{c}{**Soybean**} & \multicolumn{3}{c}{**Maize**} \\ \hline
**Parameter** & **WHC** & **DoM** & **WHC\({}^{\bullet}\)DoM** & **WHC** & **DoM** & **WHC\({}^{\bullet}\)DoM** \\ \hline NDVI & 2.5 ns & 13.3 *** & 0.9 ns & 12.1 *** & 120.7 *** & 1.1 ns \\ EVI & 5.0 ** & 65.8 *** & 0.9 ns & 8.2 *** & 245.5 *** & 2.4 ** \\ OSAVI & 2.0 ns & 19.8 *** & 0.9 ns & 9.2 *** & 319.5 *** & 1.5 ns \\ REIP & 2.8 ns & 45.0 *** & 0.9 ns & 7.5 *** & 352.1 *** & 2.1 * \\ rNDVI & 25.4 *** & 12.3 *** & 0.6 ns & 11.8 *** & 170.1 *** & 1.2 ns \\ \hline TCARI & 27.9 *** & 16.3 *** & 2.0 * & 0.3 ns & 64.0 *** & 3.1 ** \\ TCARI/OSAVI & 29.5 *** & 14.1 *** & 1.8 * & 1.8 ns & 14.7 *** & 2.6 ** \\ R\({}_{\rm{(700)/670)}}\) & 38.5 *** & 1.3 ns & 1.5 ns & 6.9 *** & 10.9 *** & 1.2 ns \\ PSNDC & 3.4 * & 2.4 * & 0.7 ns & 5.4 ** & 118.3 *** & 1.0 ns \\ mARI & 5.6 ** & 17.1 *** & 1.7 ns & 13.1 *** & 77.6 *** & 1.0 ns \\ \hline PRI & 1.1 ns & 13.7 *** & 1.4 ns & 0.1 ns & 3.0 ** & 0.3 ns \\ sPRI & 38.5 *** & 2.0 ns & 1.4 ns & 3.5 * & 54.8 *** & 1.1 ns \\ PRI\({}_{\rm{(570^{-}515)}}\) & 34.1 *** & 5.4 *** & 2.1 * & 3.1 * & 70.3 *** & 0.5 ns \\ \hline T\({}_{\rm{L,Rad}}\) (\({}^{\circ}\)C) & 9.9 *** & 7.9 *** & 2.0 * & 1.7 ns & 7.3 *** & 2.8 ** \\ AT (\({}^{\circ}\)C) & 9.9 *** & 5.1 *** & 2.0 * & 1.7 ns & 6.7 *** & 2.8 ** \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Two-way ANOVA test results of seasonal leaf radiometric temperature (T\({}_{\rm{L,Rad}}\)), leaf–air difference temperature (\(\Delta\)T), and vegetation indices (VI), calculated from the hyperspectral sensor described in Table 2, for water holding capacity (WHC) groups and days of measurements (DoM). Numbers indicate F-value and symbols \(p\)-value (* \(p\)-value \(<\) 0.05, ** \(p\)-value \(<\) 0.01, ** \(p\)-value \(<\) 0.001, and ns = not significant). Figure 5: Comparison between soil water levels: Wet/control (100% Water Holding Capacity, WHC), Mid (70% WHC) and Dry (40% WHC) for each crop: soybean (blue boxes) and maize (dashed reddish boxes) T\({}_{\rm L,Rad}\), NDVI, TCARI, EVI, sPRI, rNDVI, R\({}_{\rm 700/670}\) REIP. Dots in maize and crosses in soybean represent the seasonal average of the six replicates for each crop. Boxplots contain six replicates. Boxes show the 25 th and 75 th percentiles of the interquartile range (IQR), the horizontal line represents the median of the data and whiskers extend from the edges of box to show 1.96 IQR. Points outside this range are outliers. Different letters indicate that differences are significant at \(p\)-value \(<\) 0.05 level. Figure 6: Linear correlation between vegetation indices (VI) (Table 2) and leaf–air temperature difference (\(\Delta\)T in \({}^{\circ}\)C) vs. leaf photosynthetic CO\({}_{2}\) assimilation rate (A in \(\mu\)mol CO\({}_{2}\) m\({}^{-2}\) s\({}^{-1}\)), leaf stomatal conductance (g\({}_{\rm{s}}\) in mol H\({}_{2}\)O m\({}^{-2}\) s\({}^{-1}\)), leaf transpiration rate (T\({}_{\rm{r}}\) mmol H\({}_{2}\)O m\({}^{-2}\) s\({}^{-1}\)), SPAD chlorophyll content (chl in \(\mu\)g m\({}^{-2}\)), and canopy height (h\({}_{\rm{c}}\) in m) for soybean (blue crosses) and maize (red dots). Points represent the average of six replicas. Coefficient of determination (R\({}^{2}\)) is shown and \(p\)-value is represented with stars (* \(p\)-value \(<\) 0.05; ** \(p\)-value \(<\) 0.01; *** \(p\)-value \(<\) 0.001).