Term Name:	photoperiodism
Synonyms:	response to day length, response to night length, response to photoperiod
Definition:	Any process that results in a change in state or activity of an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of detection of, or exposure to, a period of light or dark of a given length, measured relative to a particular duration known as the 'critical day length'. The critical day length varies between species.
Ontology:	GO: Biological Process [GO:0009648]    QuickGO    AmiGO