When the dark period of short-day plants is interrupted by a brief exposure of light,then the plant:

The phytochrome was discovered by

Assertion $(A)$: Vernalization is acceleration of subsequent flowering by low temperature treatment.
Reason $(R)$: Site of vernalization is apical meristem.

If a plant needs $10$ hours of darkness to flower,identify the condition under which it will flower:
$I.$ $14$ hours day period
$II.$ $10$ hours dark period
$III.$ $9 \frac{1}{2}$ hours dark period
$IV.$ $9$ hours dark period
Choose the correct option:

Flowering of plants by exposure to low temperature is called

Phytochrome is involved in: