Physiology of Photoperiodism

Type :

Presentation

Pages :

5 pages

Format :

.doc

Published date :

11/11/2008

Category :

Science & technology

Sub category :

Biology

Oboulo.com selection criteria

$ 10.95 Add to cart

Summary :

Introduction.
Discovery and variation
1. The response of plants to the daily duration of light.
2. The length of the day and night.
Transmissible signals.
1. A common feature of photoperiodism.
2. The signal passing between leaves and response sites.
Pathways to flowering in Arabidopsis.
1. The predominance of the different pathways.
2. Expression of the floral-integrator genes.
Floral promotion pathways.
Conclusion.

Abstract

photoperiodism can be defined as the response to changes in day length that enables plants (or any other living organism) to adapt to seasonal changes in their environment. Except at the equator, the passage of the year is marked by a continuous but highly reproducible variation in the length of the day. In order to locate the time of year accurately, a timekeeping mechanism operates with precision as part of the plant's photoperiodic sensing mechanism in a way that is insensitive to less predictable variations in the environment such as temperature. Photoperiod alone is not an unambiguous signal as any particular day-length occurs twice in an annual cycle. Progressive changes in day length, which are at their greatest around the equinoxes in spring and autumn, do, however, provide a certain environmental signal for the passage of the seasons. The seasonal range and rate of change of day length is lower in the tropics than at higher latitudes and photoperiodic mechanisms need to be sufficiently precise and flexible to operate across the entire range of day lengths.