photoperiodism
/ˌfoʊtoʊˈpɪriəˌdɪzəm/
noun
- The biological response of an organism to changes in the length of day and night.
- Photoperiodism explains why some trees lose their leaves in autumn.
- The study of photoperiodism helps farmers predict when crops will flower.
- Hibernation in many mammals is triggered by photoperiodism.