What is the role of phytochrome in seed germination?
Of the various photoreceptor systems, phytochrome plays an especially important role in seed germination. Phytochrome A photo-irreversibly triggers the photoinduction of seed germination after irradiation with extremely low fluence light in a wide range of wavelengths, from UV-A, to visible, to far-red.
Which form of phytochrome triggers lettuce seed germination?
Pfr form
The Pfr form is thought to be the bioactive form in the induction of lettuce seed germination. It has been demonstrated that phytochrome is encoded by a small multigene family, and it was suggested that lettuce seed germination may be regulated mainly by phytochrome B (Kendrick and Kronenberg, 1994; Shinomura, 1997).
What is required for the germination of lettuce seed?
Water and light are fundamental to the process of lettuce seed germination. Choose a spot that receives a minimum of four to six hours of direct, full sunlight each day. If direct seeding, scatter the lettuce seeds lightly and evenly over a moist, but not soaking wet, soil surface.
Which hormone is responsible for germination in photoblastic seed?
The germination of photoblastic lettuce seeds is regulated by phytochrome, which is a red (R) and far-red (FR) light receptor in plants (Butler et al., 1959).
What is the role of phytochrome?
Phytochromes regulate light-induced developmental transitions as well as adaptation to growth under dense canopy. Plant phytochromes have antagonistic and synergistic roles in regulating photoperiodic flowering in Arabidopsis.
What is the role of phytochrome in plants?
Phytochromes are a class of photoreceptor in plants, bacteria and fungi used to detect light. They regulate the germination of seeds (photoblasty), the synthesis of chlorophyll, the elongation of seedlings, the size, shape and number and movement of leaves and the timing of flowering in adult plants.
What is the importance of phytochrome system?
The Phytochrome System in Seeds In seeds, the phytochrome system is used to determine the presence or absence of light, rather than the quality. This is especially important in species with very small seeds and, therefore, food reserves.
How long lettuce seeds germinate?
Some lettuce seedlings will even tolerate a light frost. Lettuce can be sown after soils reach 40°F (4°C), though seeds germinate best at 55 to 65°F (13 to 18°C). Seedlings will typically emerge in 7 to 10 days.
What is phytochrome plant?
Phytochromes are a class of photoreceptor in plants, bacteria and fungi used to detect light. Phytochromes control many aspects of plant development.
Which hormones are involved in seed germination?
Plant hormones, mainly abscisic acid (ABA) and gibberellin (GA), are the major endogenous factors that act antagonistically in the control of seed dormancy and germination; ABA positively regulates the induction and maintenance of dormancy, while GA enhances germination.
