In days following cold nights, photosynthesis is reduced[3,4]; however, the mechanisms underlying the inhibition of photosynthesis under LNT remain unclear. In addition, photosystemII (PSII) has long been considered as the component
of the photosynthetic system that is most sensitive to chilling[5]. Nevertheless, recent studies have suggested that LNT does not cause serious damage to PSII; instead, it inhibits its repairmechanism [6]. Photoinhibition refers to the decline in photosynthetic efficiency under the conditions in which the input of photons exceeds the requirement for photosynthesis [7]. Low temperature and high irradiance induce PSII photoinhibition and photooxidation in tropical plants [8]. The photoinhibition of photosystem I (PSI) in chilling-sensitive plants occurs during chillingstress under low irradiance [9].Reportedly, the activity of PSI decreases by approximately 70–80% when cucumber leaves were
subjected to 5 ◦C with an irradiance of 100 mol m−2 s−1 [10]. Although light is an essential factor in the photoinhibition of
PSI, chilling temperature plays a crucial role in inducing photoinhibition. Little is known about the effects of LNT on the
acceptor or donor side inhibition of PSI in tomato leaves in vivo.