1. The length of time each day during which an organism is exposed to light, especially sunlight; the daily period of illumination.
Usage: Common in biology and ecology contexts; Often used in discussions of plant and animal behavior

Examples

• Plants use photoperiod to determine when to flower and when to enter dormancy.
• The changing photoperiod in autumn triggers migration in many bird species.
• Farmers can manipulate the photoperiod in greenhouses to control plant growth.
• A longer photoperiod in spring signals to animals that breeding season is approaching.
• Some crops are sensitive to photoperiod and will only produce fruit under specific light conditions.