Vernalisation can be reversed by

Describe $(1)$ Photoperiodism.

Fill in the blanks:
$(1)$ ........ initiate rooting.
$(2)$ The pigment involved in photo-perception in flowering plants is ........

Photoperiodism is substituted by

$A$ group of plants shows flowering in a $12$ hour day and $12$ hour night cycle. When the night phase of another group of the same plants is interrupted by a brief flash of light, flowering does not occur. In which of the following groups would you place these plants?

Which of the following factors influence the process of flowering?