of Ja (O2-dependent) under LNT indicated a greater rate of electron transport to O2. This result is consistent with that observed in cucumber leaves under low temperatures [2]. Ja (O2-dependent) is thought to be driven by the water–water cycle [25]. Changes in Ja (O2-dependent) were consistent with those of the antioxidants and ROS accumulation (Figs. 6 and 7). Thus, the water–water cycle plays a double role at 9 and 6 ◦C for 9 d of stress exposure