Photoperiodism: The tendency of plants to respond to the comparative length of day and light is called Photoperiodism. It can also be defined by the following way-
The influence of the length of day and light upon flowing is called photoperiodism. Photoperiodism is a term in biology for the way a plant or animal reacts to the amount of light it gets at a time, including flowering or not flowering.
An example of photoperiodism is when a plant doesn’t bloom during the increased darkness of winter time.
Photoperiod: Photo means light and period means the length of time, so photoperiod means the length of time of light. It is response of an organism to change in day length i.e.photoperiod is related to the duration of sunlight. Growth of plant &flowering are dependent on sunlight.
Photoperiods are related to duration of sunlight. Photoperiod is the favorable day length for flowering of a plant.