Figure 2.

(A) Net photosynthetic rate (P_N), (B) stomatal conductance (g_s), (C) transpiration rate (E), (D) intracellular CO₂ concentration (C_i), and (E) leaf temperature in the first fully expanded leaves of tomato from the top during different treatments. “a[CO₂]” and “a[CO₂] + M” indicates 400 ppm CO₂ concentration without and with melatonin application. “e[CO₂]” and “e[CO₂] + M” indicates 800 ppm CO₂ concentration without and with melatonin application. “Control”, 25/20 °C + irrigation; “DS”, drought stress, 25/20 °C + no irrigation, “CS”, cold stress, 12/12 °C + irrigation; “R1” and “R2”, recovery, 25/20 °C + irrigation. The data represent average values ± SD (n = 3). The ANOVA was conducted within all the treatments at different stages. Different small letters showed significant differences (p < 0.05).