Circadian Rhythm

Definition - What does Circadian Rhythm mean?

Like other living things, plants are governed by a circadian rhythm that allows them to be active during the daylight and inactive at night, maximizing their ability to benefit from sunlight and minimizing energy loss when light is not available.

A circadian rhythm is best described as a type of internal clock possessed by most creatures that allows them to be active during the daylight hours and inactive during the nighttime hours. It is the natural cycle of activities in living things.

In plants, the circadian clock regulates response to light energy, cold, drought, and osmotic stress, and provides a timing mechanism that lets plants recognize changing seasons and prepare for coming conditions.

MaximumYield explains Circadian Rhythm

Plants, like humans, have a circadian rhythm. During the day, many flowers will open, so that petals can better absorb light and to attract pollinators. Plants also turn with the sun, ensuring maximum light absorption by leaves. Plants also exhibit a markedly different growth rate during different times of day.

However, plants do exhibit some “sleep movements”, or activities during inactive hours. For instance, leaves may open or close, or even move slightly from their daytime position.

It is possible to trick a plant and alter its circadian rhythm, though. This is often done in indoor gardening set-ups and can allow for much faster growth and maturation of a plant. Rather than relying on a set 12 hours of light and 12 hours of dark, growers can manipulate light levels so that plants have closer to 24 hours of light.

However, too much light should be avoided. Most plants benefit from 16 hours of light, and eight hours of dark, although some can thrive with 18 hours of light, and six hours of dark. Programmable lighting systems can be used to mimic natural light patterns, or to create ideal growing conditions based on a plant’s development stage and a grower’s specific goals, as well.

The amount of light a plant requires is generally referred to as its photoperiod, whereas the circadiam rhythm is a term that relates to how the plant functions in nature.

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