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Related to photoperiods: sporophyte, gametophyte


The daily duration of light and dark to which an organism is exposed, considered especially with regard to its effect on growth and development.

pho′to·pe′ri·od′ic (-ŏd′ĭk) adj.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(Botany) the period of daylight in every 24 hours, esp in relation to its effects on plants and animals
ˌphotoˌperiˈodic adj
ˌphotoˌperiˈodically adv
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(ˌfoʊ təˈpɪər i əd)

the interval in a 24-hour period during which an organism is exposed to light.
pho`to•pe`ri•od′ic (-ˈɒd ɪk) adj.
pho`to•pe`ri•od′i•cal•ly, adv.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
References in periodicals archive ?
5A; 5B) were also increased and inconsistent with previous studies (He et al., 2001; Zhang et al., 2010; Li, 2012), this might be due to the difference in periods of shading or could be associated with the plant growth and development characterization in the adzuki bean plants in response to the photoperiod. Endogenous hormones play an important role in regulating the plant development and flowering process under varied photoperiods (Metzger, 1995).
Four conditioning regimes were assayed by combining different temperatures and photoperiods. In the first one, natural environmental conditions, temperature, and photoperiod were set to follow the average conditions in the Ria de Noia during the winter period: temperature ranged from 14[degrees]C to 17[degrees]C and photoperiod from 10 to 14 h daylight, throughout the 3 mo of the experiment.
interruptus under different photoperiods, four light regimes were used with three replicates for each treatment (light: dark, L: D): 24L: 0D, 12L: 12D (as control) 0L: 24D and a progressive.
Effects of three different photoperiods on the growth and body coloration of juvenile African catfish, Clarias gariepinus (Burchell).
A significant difference was observed between photoperiods in the control (no stress) treatment in PC, TG, IV and TG recovery.
Notably, how a circadian rhythm synchronizes to a light-dark cycle to produce stable entrainment is dependent on the length of the photoperiod, with different photoperiods producing characteristic phase angles of entrainment [28].
Seeds were held under dark conditions for 3 days to promote germinataion after which they were subject to 13 h photoperiods, giving integrated PAR of 5.4 mol/[m.sup.2]/day.
The study was performed on adult, three-year-old blackface ewes (n = 24) during two different photoperiods: in May/June during a SN (night:day, 8:16) period and in November/December during a LN (night:day, 16:8) period.
The present study was aimed at examining the role of hypothalamic neuropeptides genes expressions on body mass regulation under different photoperiods in Eothenomys miletus, body mass, food intake, serum leptin levels and hypothalamic neuropeptide neuropeptide Y (NPY), Agouti related peptide (AgRP), pro-opiomelanocortin (POMC), cocaine and amphetamine regulated transcript (CART) expressions were measured.
Habitat use differed between photoperiods, seemingly in accordance to species-specific diurnal activity patterns.