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Circadian and solar clocks interact in seasonal flowering
Author(s) -
Yeang HoongYeet
Publication year - 2009
Publication title -
bioessays
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.175
H-Index - 184
eISSN - 1521-1878
pISSN - 0265-9247
DOI - 10.1002/bies.200900078
Subject(s) - zeitgeber , circadian rhythm , dusk , circadian clock , biology , noon , rhythm , bacterial circadian rhythms , infradian rhythm , entrainment (biomusicology) , chronobiology , light effects on circadian rhythm , ecology , atmospheric sciences , ultradian rhythm , neuroscience , medicine , physics
The plant maintains a 24‐h circadian cycle that controls the sequential activation of many physiological and developmental functions. There is empirical evidence suggesting that two types of circadian rhythms exist. Some plant rhythms appear to be set by the light transition at dawn, and are calibrated to circadian (zeitgeber) time, which is measured from sunrise. Other rhythms are set by both dawn and dusk, and are calibrated to solar time that is measured from mid‐day. Rhythms on circadian timing shift seasonally in tandem with the timing of dawn that occurs earlier in summer and later in winter. On the other hand, rhythms set to solar time are maintained independently of the season, the timing of noon being constant year‐round. Various rhythms that run in‐phase and out‐of‐phase with one another seasonally may provide a means to time and induce seasonal events such as flowering.