Which of the following is a long day plant?

Which type of plants can blossom throughout the year?

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:

The pigment phytochrome is involved in:

Photoperiod is an important factor which affects

The name 'phytochrome' was given by