Phytochrome occurs in two forms. In which form does it promote the germination of seeds of some species?

Define the following terms:
$(1)$ Development
$(2)$ Light period

For flowering,the critical dark period should always be exceeded in

The relation of flowering to the lengths of light and dark periods was investigated by two experiments. In one experiment,the plants were subjected to dark periods of various lengths while the light periods were kept at $4$ hours. In the second experiment,plants were kept in dark periods of various lengths while the light periods were kept at $16$ hours. The number of flowers formed in relation to these periods is shown in the table. These results indicate that flowering:

Dark periods (hours)	Flowers formed (Light: $4$ hrs / $16$ hrs)
$8$	$0$ / $0$
$10$	$0$ / $0$
$12$	$4$ / $6$
$14$	$5$ / $7$
$16$	$5$ / $8$

Florigen is produced in the region of

$A$ short-day plant was exposed to alternating red-far red light treatments. What would happen if the last treatment was of far-red light?