Photoperiodism

Under the influence of the photoperiodism reaction, plants pass from vegetative growth to flowering. This feature is a manifestation of the adaptation of plants to the conditions of existence, and allows them to move on to flowering and fruiting at the most favorable time of the year. In addition to the reaction to light, a reaction to temperature effects is also known - the vernalization of plants.

For the perception of photoperiodic conditions in plants, special leaf receptors (for example, phytochrome ) are responsible.
Plants are divided into long-day ones that bloom in continuous daylight for more than 12 hours, such as rye, carrots, onions, and short-day ones that bloom in continuous daylight for less than 12 hours, such as chrysanthemums, dahlias, asters, cabbage. There are neutral ones, for flowering they need 12 hours, for example grapes, dandelions, lilacs. In temperate latitudes, short days in spring, and long days in mid-summer. Therefore, short-day ones bloom in spring and autumn, and long-day ones bloom in summer. But you should also consider the homeland of plants, air temperature and even soil fertility.

Photoperiodism is also known in animals - insects , fish , birds , mammals . The reaction to daylight hours regulates the start of the breeding season, molting , hibernation , etc.

• Saulich A. Kh., Volkovich T. A. Ecology of insect photoperiodism: Textbook. manual - SPb .: Publishing house of S.-Petersburg. University, 2004 .-- 275 p.
• L.A. Aksenova . Plant physiology. - M.: Publishing House OL VZMSh, 2003.
• D. E. Sannikov - “Teaching of Biology”, part 1

• Photoperiodism - an article from the Great Soviet Encyclopedia .