Photoperiod Stress in Plants: A New Look at Plant Response to Abnormal Light-Dark Cycles

The article presents a review of recent studies that have experimentally shown that sudden changes in photoperiod as well as abnormal light-dark cycles provoke stress response in plants, which is called photoperiod stress. Photoperiod stress, like other stresses, causes numerous changes and/or disturbances in plants, the accumulation of which can lead to their death. Sudden changes in the photoperiod, in particular, its prolongation, cause increased generation and accumulation of ROS and induce oxidative stress in plants. The strength of the photoperiod stress response depends on the light duration. Longer prolongations of the light phase induce a true stress (distress), while shorter prolongations, on the contrary, may present a beneficial stress (eustress). In relation to photoperiod stress, all plants can apparently be divided into groups, for example, sensitive, tolerant and highly tolerant. It is fundamental that such a division differs from the generally accepted classification of plants into three categories according to photoperiodic response of flowering (short-day, long-day and day-neutral plants).