PLANT RESPONSES TO A SHORT-TERM DAILY TEMPERATURE DROP: EFFECT OF PHOTOPERIOD AND COMPARISON OF PLANTS FROM DIFFERENT PHOTOPERIODIC GROUPS

Abstract

The paper summarizes and systematizes authors’ own and literary data indicating whether or not the plant response to short-term daily temperature drops depends on the photoperiod and photoperiodic group (long-day, neutral, and short-day plants). A daily shortterm temperature drop is used as an alternative to the growth retardants method of plant height control to produce compact vegetable and bedding transplants and ornamental plants. It was previously thought that long-day plants are less responsive to a temperature drop than short-day plants. Based on the analysis of the available data, it was concluded that plant response to a temperature drop does not depend on their belonging to a certain photoperiodic group, but is primarily determined by the conditions of the experiment, namely, the duration of the photoperiod. In particular, the greatest morphogenic effect of a temperature drop is manifested in a short photoperiod. As the photoperiod increases, the effect of a temperature drop gets weaker or is absent. For the effects of a temperature drop to be manifested under long photoperiods, longer temperature decreases are usually required. This is probably due to increased synthesis of gibberellins with an increase in photoperiod, which is characteristic of plants of all photoperiodic groups.