Photosynthesis is one of the main physiological processes, which is affected by low temperature (Mohabbati et al. 2013). It causes severe restrictions for the plants to function and growth. The decrease of photosynthesis induced by low temperatures is a well-known response of chilling-sensitive plants.
Most plant species are able to acclimate to changes in growth temperature by modifying the photosynthetic apparatus in a manner that helps in their survival under low-temperature stress conditions (Biswal et al. 2011). Gupta et al. (2014) observed that photosynthetic pigments, Chl a, b, and total Chl (a+b) content were significantly reduced (~0.3 to 0.9-fold) at 0ºC as compared to 25ºC in cold-sensitive plants but in cold resistant plants, though slight reduction was observed, the difference was not significant. It is well known that the chloroplast is the main organelle rapidly and deeply affected by cold stress (Ensminger et al.
2006). When plants are exposed to low-temperature stress, Chl biosynthesis is inhibited. Therefore, an imbalance in PSII is created after exposure to low temperature because of the alterations in the Ch1 antenna complexes (Habibi et al. 2011). At low temperature, the alterations in the content of total carotenoids show a tendency to a sharp increase, probably in order to increase of photon capture, as a strategy against cold-induced photoinhibition (Habibi et al.
2011). Gupta et al. (2014) observed that the total carotenoids content in the cold-sensitive plants sharply varied at a temperature range from 0 – 25?C, while no significant change was observed in the tolerant plants.
However, the overall photosynthetic performance of plants depends upon various stomatal or nonstomatal factors under cold stress (Freschi and Mercier 2012, Yamori et al. 2014). Stomata closure in response to cold stress generally occurs due to decreased leaf turgor and atmospheric pressure ultimately alters photosynthesis and the mesophyll metabolism (Medici et al. 2007, Xu and Zhou 2008).