The response of different organisms to the environmental rhythms of light and darkness is called

Florigen is synthesized in

Write a short note on vernalisation.

Given below are two statements.
Statement $I$: If the long dark period is interrupted by a brief flash of light,short day plants will not flower.
Statement $II$: When the long dark period is interrupted by a brief flash of light,long day plants can flower.
In the light of above statements,choose the most appropriate answer from the options given below:

$Nicotiana$ $tabacum$,a short-day plant,fails to flower when exposed to a light duration longer than its critical period. Explain.

The pigment involved in red-far red light interconversion is