## 3 Results and Discussion
### Crop Water Stress Index and Degrees above Non-Stress  
CWSI was calculated based on the methodology proposed by [PERSON] et al. [19], which uses a water stress baseline of 5 \({}^{\circ}\)C, and with the baselines we obtained from our measures in non-transpiring leaves (Figure 5). In accordance with the results obtained, both methodologies showed similar results; however, the method of [PERSON] et al. [19] led to slightly higher CWSI maximum values. In general, the control treatment in both young and mature trees exhibited CWSI values significantly lower than those of water-stressed trees. The CWSI values of control trees ranged from \(-0.05\) to \(0.35\) (Figure 5). Negative CWSI values were measured on days of low evaporative demand and high \(\Psi\)stem (\(-0.5\) MPa, Figure 2), and have been related to increased transpiration in almond trees [48]. The water -stressed treatment exhibited CWSI values that achieved \(0.75\) and \(0.65\) for young and mature sweet cherry trees, respectively, calculated with the upper baseline of 6 \({}^{\circ}\)C (Figure 5a,b). These CWSI values obtained in water-stressed trees were similar to those reported in nectarine trees [49] but are lower than \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Treatment** & **Slope (\({}^{\circ}\)C kPa\({}^{-1}\))** & **Intercept (\({}^{\circ}\)C)** & **R\({}^{2}\)** \\ \hline Young sweet cherry trees & \(-2.174\) & \(2.936\) & \(0.93\) \\ Mature sweet cherry trees & \(-2.962\) & \(4.738\) & \(0.92\) \\ Global relationship & \(-2.618\) & \(3.868\) & \(0.91\) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Fitted parameters for the non-water-stress baselines (\(\Delta\)T\({}_{\text{wet}}\) = a + b-VPD) for young and mature sweet cherry trees. Figure 5: Seasonal evolution of the crop water stress index (CWSI) calculated using a transpiration inhibitor [22] (**a**,**b**) and \(\Delta\)T\({}_{\text{dry}}\) equal to 5 \({}^{\circ}\)C (**c**,**d**) in young (**a**,**c**) and mature (**b**,**d**) sweet cherry trees. Each point corresponds to the mean \(\pm\) standard error of the mean for six images per treatment. Asterisks indicate statistically significant differences between treatments by ANOVA (\(p<0.05\)). CTL and S correspond to control and deficit irrigation treatment for young (\(\gamma\)) and mature (M) sweet cherry trees, respectively. FI is full irrigation period, D is drought period and R is recovery period in young sweet cherry trees (Plot 1), and 100% and 55% are the percentages of ETc applied in mature sweet cherry trees (Plot 2). those described in almond trees [48; 50], which reached values close to 1 on dates with similar values of \(\Delta\)T (4.0 \({}^{\circ}\)C). When the evolutions throughout the experiment of CWSI and \(\Delta\)T were compared, a trend that CWSI values presented sharper peaks and troughs and greater oscillations than the evolution of \(\Delta\)T values was observed, particularly in young trees. However, CWSI as a water stress indicator showed significant differences between treatments on the same days that \(\Delta\)T showed differences, and the absolute minimum and maximum values occurred on the same days in both water stress indicators. The DANS index followed the same pattern of significance as the CWSI, with significant differences between treatments on the same dates. The DANS values of young and mature water-stressed trees ranged from slightly below 0.0 \({}^{\circ}\)C when they were irrigated as control trees to over 8 \({}^{\circ}\)C at the time with the highest difference (DOY 236 and 207 for young and mature trees, respectively; Figure 6). Contrary to CWSI, the DANS index exhibited higher values in mature trees than young trees (Figure 6c,d), despite the young trees being submitted to greater water stress.