Detection of light in flowering plants

photoreception if the detection of light. this usually involves the absorption of light by a pigment known as a photoreceptor.
Light is important to plants because of the formation of chlorophyll, photosynthesis, initiates flowers, germniation and direction of growth.
Plants grown in dark condititons are said to be etiolated having yellow leaves, taller and thinner.
in the early stages of life this is an advantage as it can push through the soil more easily, faster growth to reach light wicker.

phytochrome is the photoreceptor, its a blue-green pigment present in small amounts in the leaves. it exists in two interconvertible forms Pfr and Pr.
Pr absorbs red light and is converted into Pfr, This is fast and is done in the light
Pfr absorbs far red light is converted into Pr, this is slow and is done in the dark
Pfr acts as a daylight length detector system.
Pfr promotes the flowering of long day plants
Pfr inhibits the flowering of short day plants


Germination:
seeds must take in water( IMBIBITION)
This causes the embryo to release gibberellic acid and this induces the synthesis of hydrolyic enzymes , including amylase.
Hydrolysis of starch takes place and it is broken down to maltose, this fuels respiration in the embryo so it an grow.