Photoperiodism

Photoperiodism in Plants

• Pr converts to Pfr during the day and slowly reverts to Pr at night.
• Flowering plants use circadian rhythm and photoreceptor proteins to sense seasonal changes.
• Phytochrome has two forms: P and P.
• Red light converts phytochrome to its active form (P), stimulating processes like germination and flowering.
• Cryptochromes absorb blue light and UV-A, entraining the circadian clock to light.
• Long-day plants flower when night length falls below critical photoperiod, typically in late spring or early summer.
• Short-day plants flower when night lengths exceed critical photoperiod.
• Day-neutral plants like cucumbers do not initiate flowering based on photoperiodism.
• Photoperiodism affects flowering, stem growth, and leaf loss in plants.
• Photoreceptors like phytochrome and cryptochrome play crucial roles in sensing day-length.
• Artificial lighting can induce changes in flowering time.

Photoperiodism in Animals

• Daylength is crucial for many animals, affecting biological and behavioral changes.
• Photoperiod affects insects at different life stages.
• Photoperiod triggers seasonal changes in wing frequency in water striders.
• Photoperiod influences singing frequency and song repertoire in birds like canaries.
• Daylength is registered in the suprachiasmatic nucleus in mammals, influencing hormone production.
• Photoperiod affects color changes, migration, hibernation, and sexual behavior in animals.
• Insects use photoperiod as an environmental cue for physiological processes.
• Photoperiod influences various behaviors in different animal species.

Other Organisms Demonstrating Photoperiodic Responses

• Various organisms show photoperiodic responses, including Neurospora crassa, Lingulodinium polyedra, and Chlamydomonas reinhardtii.
• Photoperiodism is observed in organisms beyond plants and animals.
• Demonstrated photoperiodic responses in various species.

Key Terms Related to Photoperiodism

• Chronobiology.
• Circadian clock.
• Circadian rhythm.
• Florigen.
• Photobiology.

Further Studies and Research on Photoperiodism

• References for further study on photoperiodism, including books and journals on plant biology.
• Studies on light perception and signaling in plants.
• Research on photoreceptors and regulation of flowering time.
• Analysis of photoperiodic sensitivity in different organisms.
• Exploration of the role of phytochromes in photoperiodic flowering.

Studies on Photoperiodism in Insects

• Insect photoperiodism and its mechanisms.
• Influence of day length on insect behavior.
• Research on the induction of adult diapause in insects.
• Control of wing polyphenism in insects by photoperiod.
• Impact of photoperiod on insulin receptor signaling in insects.

Human and Primate Photoperiodism

• Evidence of photoperiodism in humans and primates.
• Seasonality effects on human birth patterns.
• Latitudinal gradient in human birth seasonality.
• Interplay between birth seasonality and childhood disease dynamics.
• Implications of photoperiodism in humans and primates.

Photoperiodism Data Sources