photoperiod

American  

[foh-tuh-peer-ee-uhd] / ˌfoʊ təˈpɪər i əd /

noun

Biology.

1. the interval in a 24-hour period during which a plant or animal is exposed to light.

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photoperiod British  

/ ˌfəʊtəʊˈpɪərɪəd /

noun

1. the period of daylight in every 24 hours, esp in relation to its effects on plants and animals See also photoperiodism

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photoperiod Scientific  

/ fō′tō-pîr′ē-əd /

1. The duration of an organism's daily exposure to light, considered especially with regard to the phenomena of photoperiodism.

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Other Word Forms

• photoperiodic adjective
• photoperiodical adjective
• photoperiodically adverb

Etymology

Origin of photoperiod

First recorded in 1915–20; photo- + period

Example Sentences

Inside the $45 packet were five feminized, photoperiod seeds from Gogol’s Oregon farm, and they can be purchased with no more hassle — or stigma — than anything else at C&S Garden Center.

From Los Angeles Times • May 20, 2024

The LWD1 mutation thus makes barley virtually insensitive to photoperiod, which in turn makes cultivation in various latitudes and marginal environments with sub-optimal growing conditions possible.

From Science Daily • Feb. 23, 2024

A day’s photoperiod seems to tie to the initiation of breeding steps, but by the time of the year when birds are returning, they are no longer sensitive to changes in day length, she adds.

From Scientific American • Apr. 20, 2023

“The further north you are, the shorter the photoperiod during the winter,” Avery said, making northerners more likely to be affected.

From Seattle Times • Nov. 23, 2022

Although gonadal response and seasonal restriction of breeding are set by the photoperiod, specific temporal relationships are dictated by more immediate environmental variables.

From The Breeding Birds of Kansas by Johnston, Richard F.