Question

What is photoperiodism ? Classify plants based on photoperiodism.

Answer 1

Hint: The flowering is triggered in the plants and is determined by its photoperiod. When the optimum photoperiod is reached in both these plant types, then the flowering will take place simultaneously or the season will determine the flowering of the plants.

Complete answer:
The photoperiod is defined as the relative length of day and night. Some plants need to be exposed to sunlight for a particular duration of time to trigger flowering and this is the reason for the seasonal blooming of the flowers.
This phenomenon was first discovered by Charles Darwin and his son Francis in 1880.
Photoperiodism in Plants
The major number of angiosperms (called as the flowering plants) will use photoperiodism to determine the flower formation. For this process, these flowers will utilize one of the photoreceptor proteins that are present in their bodies, such as cryptochrome or phytochrome.
There exists a well-defined critical duration. This critical duration will be different for different plants and based on this duration, plants are categorized into three different categories:
Long Day Plants
The plants which are in need of more exposure to the light are called long-day plants.  Long day plants cannot be found in places where the length of the day is less. examples are radish, spinach, sugar beet, etc.
Short Day Plants
Plants that require less exposure to light are called short-day plants. Short day plants cannot be observed in places where the length of the night is less.
Examples are sunflower, rice, tobacco, etc.
Day Neutral Plants
When the flowering in a plant takes place irrespective of the day length then they are called day-neutral plants. The flowering in neutral plants is not affected by the darkness or the light. They depend on other factors such as ade or any other stimulus. Examples are pea plants, tomatoes,  etc.

Note: Apart from plants, animals also have photoperiodism. The length of the day, the season of the year, the temperature will affect the hibernation, behaviours, resizing of the sex organs and migration.