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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.


(Botany) the period of daylight in every 24 hours, esp in relation to its effects on plants and animals
ˌphotoˌperiˈodic adj
ˌphotoˌperiˈodically adv


(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.
References in periodicals archive ?
05) levels of circulating melatonin (162 [+ or -] 11 pg/mL) compared with control animals from the LN (218 [+ or -] 12 pg/mL) photoperiod during the first hour after treatment.
Variations found among cultivars are mainly due to the specific response of each genotype to temperature, photoperiod and interaction between these two factors (DROWO, 1936).
arabidopsis growth chamber: control system for temperature and photoperiod.
However, the manipulation of other factors such as light intensity and photoperiod are also important in fish production as they can optimize the production of a species as the physiological response of fish can be positively affected by variations in light intensity, wavelength and daily or seasonal photoperiod (Boeuf & Le Baile, 1999; Puvanendran & Brown, 2002; Stuart & Drawbridge, 2011; Gunnarsson et al.
The results showed that short photoperiod reduced body mass and body fat mass, and increased food intake.
These authors considered the nonlinear effects of air temperature, photoperiod and vernalization.
The combination of artificial light and natural photoperiod enables the development of lighting programs to increase the egg production (FREITAS OLIVEIRA & GEWEHR, 2010), and it is considered an essential management tool in commercial laying poultry (COENEN et al.
Trillmich (2000) suggests that a combination of low temperature and short photoperiod might influence reproduction in cavies in laboratory conditions.
Chicks were randomly placed into groups and then exposed to three photoperiod treatments: long/continuous (23 hours of light followed by 1 hour of dark within a 24-hour interval); regular/intermittent (2 hours of light followed by 2 hours of dark, repeated in succession throughout a 24-hour period); and short/non-intermittent cycle (8 hours of light followed by 16 hours of dark).
This study investigated the SD photoperiod effects on plant morphological traits, physiological parameters, flower bud differentiation characterization and yield formation.
Among different factors, photoperiod plays a vital role in synchronization of the reproductive activity (testicular growth, spermatogenesis and plasma sex steroid synthesis) through neuroendocrine system (gonadotropin production) with suitable environment in seasonal breeders (Boon et al.