PHOTOPERIODISM
Photoperiodism is the phenomenon of physiological changes that
occur in plants in response to relative length of day and night (i.e.
photoperiod).
Or
The response of the plants to the relative day length, expressed in the form
of flowering is called photoperiodism.
The phenomenon of photoperiodism was first discovered by Garner and Allard
(1920).
Depending upon the duration of the photoperiod, the plants are classified
into three categories.
1. Short day plants (SDP)
2. Long day plants (LDP)
3. Day neutral plants (DNP)
1. Short day plants : These plants require a relatively short day light period
(usually 8-10 hours) and a continuous dark period of about 14-16 hours for
subsequent flowering. These plants are also known as long-night plants E.g.
Rice, coffee, soybean, tobacco and chrysanthemum •
❖ In short day plants, the dark period is critical and must be continuous. If this
dark period is interrupted with a brief exposure of red light (660-665 nm
Photoperiodism is the phenomenon of physiological changes that
occur in plants in response to relative length of day and night (i.e.
photoperiod).
Or
The response of the plants to the relative day length, expressed in the form
of flowering is called photoperiodism.
The phenomenon of photoperiodism was first discovered by Garner and Allard
(1920).
Depending upon the duration of the photoperiod, the plants are classified
into three categories.
1. Short day plants (SDP)
2. Long day plants (LDP)
3. Day neutral plants (DNP)
1. Short day plants : These plants require a relatively short day light period
(usually 8-10 hours) and a continuous dark period of about 14-16 hours for
subsequent flowering. These plants are also known as long-night plants E.g.
Rice, coffee, soybean, tobacco and chrysanthemum •
❖ In short day plants, the dark period is critical and must be continuous. If this
dark period is interrupted with a brief exposure of red light (660-665 nm
