Photoperiodism: The Calendar of Plants

Abstract

The daylength varies with the time of the year and can thus be used by plants-and other organisms-to react photoperiodically in developmental steps and morphological features such as cyst formation, germination of zygospores and cell division in certain algae, succulence of stems and leaves, formation of storage organs, and flower induction. The functioning and molecular bases of circadian clocks of plants are mentioned and shown how they are entrained to the day, and whether they are involved in photoperiodic timing. Seasonal aspects for various crops and the evolution of photoperiodism are briefly touched upon.

Wolfgang Engelmann: Passionate Researcher, Teacher, and Artist (26 February 1934 to 1 July 2023)

“…This research was evidence of an extraretinal photoreceptor that was found years later in the form of the blue light pigment cryptochrome. This work was only possible because of Wolfgang's excellent skills in developing innovative methods for recording and analyzing all kinds of rhythms, methods that he made available to the scientific community (Engelmann, 2004). For example, he was the first to develop an automatic recording system using infrared light barriers for activity rhythms in flies (Engelmann and Mack, 1978).…”