Question

Write short note on photoperiodism

Answer 1

Photoperiodism is the physiological reaction of organisms to the length of day or night. It occurs in plants and animals. Photoperiodism can also be defined as the developmental responses of plants to the relative lengths of light and dark periods.

Answer 2

Answer:

★ PHOTOPERIODISM:-

→ Some plants require a periodic exposure to light to induce flowering.

→ Based on duration of light required, plants are 3 groups:

o Long day plants: They are the plants which require the exposure to light for a period exceeding and it's a well defined critical duration.

o Short day plants: They require the exposure to light for a period less than the critical duration before the flowering is initiated in ther.

o Day-neutral plants: They have no correlation between exposure to light duration and induction of flowering response.

→ Like the duration of light period, duration of dark period is also important.

→ The response of plants to periods of day/night is called photoperiodism.

→ While shoot apices modify into flowering apices prior to flowering, the by themselves cannot perceive photoperiods.

→ It has been hypothesised that there is a hormonal substance responsible for flowering.

→ When the plants are exposed to the necessary photoperiod, the hormone migrates from leaves to shoot apices to induce flowering.