Plant Biologists: Sunflowers Use Their Clock To Follow Sun During Day

Plant biologists have discovered sunflowers to follow the sun from east to west during the day, using their growth hormones. Young sunflowers begin their day at the east and move towards the west with the sun and get back to the east by night, thus awaiting the sun to rise at dawn. The study was funded by the National Science Foundation's Plant Genome Research Program.

Following the sun helps the plant to grow faster. In fact, this phenomenon of the sunflowers was discovered much earlier by scientists, but they did not study it in relation to the circadian rhythms.

According to UVA today, biologist Benjamin Blackman stated "Before our experiments, few studies - the latest more than 50 years ago - had assessed how sunflowers returned at night, and they had suggested some internal 'habit' was involved, but did not directly implicate the clock."

It was also found that sunflowers that follow the sun during the day grow better. Stacey Harmer, a molecular biologist and professor of plant biology at UC Davis, examines lab plant -Arabidopsis to study circadian clocks.

During their study, they found out associations between the clock genes and auxin, a plant hormone. To understand more of this, Stacey Harmer and her collaborator Benjamin Blackman started observing the sunflower.

An experiment was conducted on the sunflowers by observing a few potted sunflowers on the field facing the east towards the sun and a few were rotated to face the west. Using the infrared camera, they identified that the sunflowers that are facing the east attracted many more pollinated insects when compared to the ones facing the west, away from the warmth of the sun.

The west facing sunflowers were exposed to portable heater and this again brought pollinating insects to the flowers. This is also because insects such as bees like warm flowers.