Sunflowers use internal clock to follow the sun
Growing sunflowers begin the day with their heads facing east, swing west through the day, and turn back to the east at night.
“The plant anticipates the timing and the direction of dawn, and to me that looks like a reason to have a connection between the clock and the growth pathway,” Prof. Harmer said.
This behavior of sunflowers had been described by biologists as far back as 1898, but no one had previously thought to associate it with circadian rhythms.
The scientists carried out a series of experiments with sunflowers in the field, in pots outdoors and in indoor growth chambers.
They staked plants so that they couldn’t move or turned potted plants daily so that they were facing the wrong way.
They found that they could disrupt the ability to track the sun, and documented that plants that follow the sun get a growth boost.
Sunflowers staked so they can’t move have decreased biomass and less leaf area than those that do, the scientists found.
When plants were moved into an indoor growth chamber with immobile overhead light, they continued to swing back and forth for a few days.
Finally, the indoor plants did start tracking the sun again when the apparent source of lighting was moved across the growth chamber by turning adjacent lights on and off during the day.
Read more at Sci-News.com
