4.6 Phytochrome

There is a group of plant pigments and proteins, called phytochrome, which are important in maintaining seed dormancy or triggering germination.  Phytochrome will change its shape depending on if it is absorbing red light or infrared light.  That shape then will facilitate different chemical reactions in the plant. When phytochrome absorbs a lot of red light (indicating few competing plants present), then germination will be activated and dormancy broken.  In contrast, if phytochrome absorbs less red and more infrared, seeds will remain dormant because there is not enough light in that area to support more plants.  Dr. Namuth-Covert walks through this concept in the next video clip.