After the study of the time course of Tleaf and the thermal index Tleaf–air, together with the gas-exchange measurements,the second step in this experiment was to define the hypothetical relationships between these parameters. If significant relationships were defined, then, we could conclude that an easy way to monitor the crop–water status is to use the leaf (or canopy) temperature as the main source of information. In agreement with this, no significant correlations between temperature related parameters (Tleaf and Tleaf–air) and leaf gas exchange measurements were found at the beginning of the experiment (0 DAT) (Fig. 4A–C; Table 3). By the contrast, these correlations were highly significant (p < 0.05) at9 and 14 DAT (Fig. 4A–C; Table 3). According to these linear cor-relations; higher Tleaf values were related to lower transpiration,stomatal conductance and net photosynthesis. However, these lin-ear regressions were different for 9 and 14 DAT, and even more for those determined with the dataset corresponding to 0 DAT.