photoperiodicity

photoperiodism

[foh-tuh-peer-ee-uh-diz-uhm]
noun Biology.
the response, as affecting growth or reproduction, of an organism to the length of exposure to light in a 24-hour period.
Also called photoperiodicity [foh-toh-peer-ee-uh-dis-i-tee] .


Origin:
1915–20; photoperiod + -ism

Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
Cite This Source Link To photoperiodicity
Collins
World English Dictionary
photoperiodism (ˌfəʊtəʊˈpɪərɪəˌdɪzəm)
 
n
the response of plants and animals by behaviour, growth, etc, to photoperiods

Collins English Dictionary - Complete & Unabridged 10th Edition
2009 © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009
Cite This Source
American Heritage
Medical Dictionary

photoperiodism pho·to·pe·ri·od·ism (fō'tō-pĭr'ē-ə-dĭz'əm) or pho·to·pe·ri·o·dic·i·ty (-pĭr'ē-ə-dĭs'ĭ-tē)
n.
The response of an organism to changes in its photoperiod, especially as indicated by vital processes.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Cite This Source
American Heritage
Science Dictionary
photoperiodism (fō'tō-pîr'ē-ə-dĭz'əm) also photoperiodicity   (fō'tō-pîr'ē-ə-dĭz'əm)  Pronunciation Key 
The response of an organism to changes in its photoperiod, especially as indicated by vital processes. For example, many plants exhibit photoperiodism by flowering only after being exposed to a set amount of daylight, as by requiring either a long or short day to flower. Plant growth, seed germination, and fruiting are also affected by day length. Photoperiodic responses in plants are regulated by special pigments known as phytochromes. In animals, migration, mating, amount of sleep, and other behaviors are also photoperiodic. In many animals, photoperiodism is regulated by the hormone melatonin.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
Cite This Source
Related Words
Copyright © 2014 Dictionary.com, LLC. All rights reserved.
  • Please Login or Sign Up to use the Recent Searches feature
FAVORITES
RECENT

;