Phytochrome + Photoperiodism

Cards (10)

What is phytochrome?
It is a pigment that is not a hormone, it detects light.
Pr - absorbs red light
Pfr - absorbs far-red light
What is phytochromes active form?
Pfr : found in plants not under the canopy and in spring and fall
What is phytochromes inactive form?
Pr : found in dark-grown or shaded plants. Red light is absorptive by the canopy while the far red light reaches the forest floor
What does Pfr promote?
Normal growth, flowering and the germination of seeds
What does Pr promote?
Etiolated growth, seed germination is inhibited and no flowering
What is photoperiodism?
plant response to length of day
Short Day Plants?
Flower when there is less than 12-14 hours of uninterrupted daylight.
"long night" plants flower when there is 10-12 of uninterrupted darkness.
Long day plants?
Flower in 12-14 hours of daylight.
"short night" plants flower in less than 10-12 hours of darkness
Ex: spinch, potatoes, lettuce, wheat
Day neutral plants?
Unaffected by photoperiod, are often tropically grown plants
Ex: carnations, garden beans, tomatoes, roses, cottons, dandelions
Do some plants need red light to germinate?
Yes, when seeds emerge Pr is changed to Pfr to reduce ethylene production as well as the elongation of stems