What is the response of various organisms to the duration of light and dark periods called?

Explain the role of light in flowering.

$A$: Only bud or embryo can be vernalized.
$R$: Vernalization requires dividing cells.

It is known that some varieties of wheat are sown in autumn but are harvested around next mid-summer.
$(A)$ What could be the probable reason for this?
$(B)$ What term is used for this promotion of flowering under low temperature?
$(C)$ Which plant hormone can replace the cold treatment?

The wavelength of light absorbed by the $P_r$ form of phytochrome is (in $nm$)

There are many plants that do not show any correlation between exposure to light duration and the induction of flowering. Such plants are called $..........$.