## 4 Conclusions  
The use of thermal imaging obtained from low-cost devices provided reliable data which were used to obtain the thermal indicator Tc and to calculate the thermal indices \(\Delta\)T, CWSI, DAC and DANS to assess the response of young and mature sweet cherry trees submitted to water stress. Our results revealed that Tc was highly dependent on weather conditions, while the thermal indices mitigated this dependency, so the use of Tc in water stress detection is not recommended. \(\Delta\)T was highly influenced by VPD, and when upper and lower baselines were obtained there were no differences found either between young and mature sweet cherry trees or between plots, which supports the use of the proposed baselines. CWSI and DANS were strongly related to \(\Psi\)stem and were calculated on the basis of the experimental non-water-stress baseline and water stress baseline, over a range of VPD values between 1 and 4 kPa. The DANS index differentiated between irrigation treatments as well as CWSI, despite being much easier to calculate than CWSI, and exhibited a strong relationship with \(\Psi\)stem. These results indicate that the DANS index is a promising thermal index which can be used in fruit tree water assessment. It must also be added that CWSI and DANS resulted in different regression lines with \(\Psi\)stem, depending on the plot studied. These differences might not be solely attributable to the different age of the trees but also to the different soil and weather conditions of each plot. When thermal indices were compared with \(\Psi\)stem, it was observed that, under non-limiting soil water conditions (values below \(-0.7\) MPa), all indices were highly influenced by climatic conditions. Moreover, despite thermal indices being a non-invasive and fast means with which to assess tree water status, Tc strongly depends on crop transpiration rate. This is a limiting factor in the interpretation of thermography data for the early detection of water stress, so in phenological stages when even slight water stress must be avoided, its use should be coupled with other water status indicators. However, when deficit irrigation was applied, CWSI and DANS could be considered reliable water  
Figure 9: Relationship between midday stem water potential (\(\Psi\)stem) and (**a**) degree above control treatment (DAC) and (**b**) degree above non-stress baseline (DANS). Relationship between crop water stress index (CWSI) and (**c**) DAC and (**d**) DANS. Each point corresponds to the mean \(\pm\) standard error of the mean of 6 measurements per treatment. CTL and S correspond to control and deficit irrigation treatment for young (Y) and mature (M) sweet cherry trees, respectively. stress indicators. The results of this study could help improve sweet cherry cultivation, as well as other _Prunus_ fruit trees with similar phenology and water stress behavior such as extra early plum trees, and not only in areas where water is scarce, but in regions where water availability is not currently a problem and sweet cherry trees are mainly rainfed, to assess the tree water status. Conceptualization, P.J.B.-R., V.B., R.T.-S. and R.D. ; methodology, P.J.B.-R., V.B. and R.D. ; software, R.T.-S. and F.S.-V; validation, V.B., P.J.B.-R. and R.D. ; formal analysis, V.B. and P.J.B.-R.; investigation, P.J.B.-R., V.B., F.S.-V., R.T.-S. and R.D. ; resources, F.S.-V., R.T.-S. and R.D. ; data curation, P.J.B.-R. and V.B. ; writing--original draft preparation, V.B. and P.J.B.-R.; writing--review and editing, R.D. and R.T.-S.; visualization, P.J.B.-R. and V.B. ; supervision, P.J.B.-R., V.B., R.D. and R.T.-S.; project administration, R.D. and R.T.-S.; funding acquisition, R.D. and R.T.-S. All authors have read and agreed to the published version of the manuscript. This research was funded by the Spanish Economy and Competitiveness Ministry (MINECO) and the European Agricultural Funds for Rural Development.