A long time ago, people noticed that young sunflower flowers turn to follow the sun during the day, and at night they return to their original position to meet it again in the east in the morning. But until now, scientists have not been able to solve this mystery: what makes plants perform their daily ritual and why does the “worship” of the luminary stop over time?

In search of an answer, Stacey Harmer from the University of California at Davis and her colleagues conducted a series of experiments.

At the first stage, conditions were changed for sunflowers growing in their natural environment. Scientists “immobilized” one group so that the plants could not turn at all, and the other was fixed in such a way that the sunflowers at sunrise were turned to the west. When the flowers grew, it turned out that the leaves in both groups were 10% smaller than those of the “free” plants. This confirmed the hunch that observing the sun is necessary for sunflowers to grow more efficiently.

Then the scientists decided to check whether the rhythmic “dancing” of sunflowers was due to internal clocks or environmental conditions.

They moved the plants that were growing outside into a room with constant overhead lighting and found that the sunflowers continued to turn from side to side exactly as they had before for several days.

The scientists then placed the plants in a special room with a string of lamps that turned on one at a time, imitating the movement of the sun. When the researchers programmed artificial lighting on a thirty-hour day/night cycle, the plants turned from side to side without a regular schedule. But when light conditions returned to normal, the sunflowers strictly followed the artificial "sun", showing that internal circadian rhythms play an important role in flower movement.

But most of all, biologists were interested in the question of why, after flowering, sunflowers stop turning from side to side and freeze, “looking” towards the sunrise. Then Harmer's team turned some of the plants to the west, and then counted the number of bees and other pollinators that landed on flowers facing different directions.

It turned out that in the morning, insects visited flowers facing east five times more often than those facing in the opposite direction.

“You can see that bees go crazy for east-facing flowers and pay little attention to west-facing plants,” says Stacy Harmer.

Previous research has shown that pollinators prefer warmer flowers, so sunflowers that receive a large dose of early morning light appear to be more popular.

“I was constantly amazed at how complex plants are,” continues Harmer. “They are truly masterful at adapting to environmental conditions.”

The study, published in Science, raises more complex questions. For example, how do plants tell time and how do they find the right direction when they turn in the dark to where the sun will rise?

But, according to experts, the very fact that sunflowers have an internal clock and are guided by their own rhythms is the “Holy Grail” in the study of their complex behavior. And, as the university press release highlights, this is the first example of temporal synchronization in plants living in natural environments, which has a direct impact on growth efficiency.

MOSCOW, August 5 - RIA Novosti. Sunflowers have the amazing ability to constantly “look” at the Sun thanks to a mutation that has changed the functioning of their “internal clock” in such a way that they orchestrate the growth of its cells in an extremely unusual way, causing the inflorescence to rotate from east to west during daylight hours, says an article published in Science magazine.

“The fact that the plant has an idea of ​​when and where the Sun will rise made me assume that there is a connection between the “bioclock” and the chain of proteins and genes that control the growth of sunflowers. In addition to the fact that this way the flower receives more light, it It also attracts bees more because they like warm surfaces,” said Stacey Harmer from the University of California at Davis (USA).

Based on this assumption, Harmer and her colleagues uncovered one of the oldest and most interesting mysteries in botany by studying the work of the so-called circadian rhythms, which control all processes inside plant and animal cells depending on the time of day, and their influence on the work of oxin, a stimulator protein growth.

To do this, the authors of the article grew several sunflowers, some of which were planted in a laboratory where the light was constantly on, and others in a regular field. Scientists fixed some of the plants in tubs in such a way that they could not turn behind the Sun, which allowed them to assess the consequences of abandoning such an evolutionary adaptation.

In revealing the principles of this movement, they were helped by an ingenious technique invented by one of the authors of the article - the biologists took a marker and marked several points on the stem of a sunflower, which they monitored with a video camera. If the distance between them changed, it meant that the flower stem was growing where these points were drawn.

As observations have shown, the “motor” in the movement of a flower was the plant’s internal clock - a set of light-sensitive proteins and genes “connected” to them that control various life processes associated with the onset of day, night, morning and evening.

If the length of the day changed artificially, then the sunflowers lost the ability to orient themselves towards the Sun, even if the artificial light source moved across the “sky” in the same way as the real star. This immediately had a negative impact on the growth rate of the flower, biomass gain, and seed development.

The marker "dots" revealed exactly how this happened - it turned out that these clocks influence the movement of the flower in two ways: by controlling the rate of growth and by causing one side of the stem to grow faster than the other. Thanks to this, the sunflower gradually turns during the daylight hours, following the Sun.

This sunflower trait may have one unexpected evolutionary benefit - Harmer and her colleagues found that bees like warm flowers, especially in the morning, and turning toward the sun helps the flower warm up faster and attract more pollinators.

Material. Those differences in material expansion due to temperature. More in the sun than in the shade. As far as I know, the base of the head at the place where the stem is attached looks like “hard cotton wool” with liquid. Maybe this liquid in the pores plays the role of muscles - are there any hydraulic operators?

[email protected] 01.08.2011

VIVAT - GOOGLE!

Name: comes from a combination of two Greek words “helios” - sun and “anthos” - flower. This name was not given to it by chance. Huge sunflower inflorescences, bordered by bright radiant petals, really resemble the sun. In addition, this plant has the unique ability to turn its head after the sun, tracing its entire path from sunrise to sunset.
Plants do not have muscles; the flower can change orientation only due to the fact that the stem that holds it grows stronger on the sunny side. This is why the process occurs as the sunflower grows: during the day, the closed flowers actually follow the course of the sun, justifying their French name tournesol.

An even more amazing trick: during the night, the flowers manage to turn so that in the morning they again greet the sun in the east.
Thanks to this rotation, plants in the growth phase are able to capture 10-15 percent more solar energy. A grown sunflower with an open flower looks motionlessly to the east.
The area of ​​the stem under the flower petals contains<гормон роста>. This hormone cannot withstand direct sunlight. When exposed to the sun, this part of the stem turns to move away from it. It concentrates<гормон роста>, so it grows faster, and as a result the flower itself turns towards the sun.

So I was thinking in the right direction, I just couldn’t imagine that a plant could grow so quickly. Thanks to Google, I somehow didn’t think to Google this question. But beautiful pictures appeared in the topic. Did you know that in Germany it is customary to make bouquets of sunflower flowers? You may well be given such a bouquet for your birthday.

Alexey.n.pop***@u*****.ua Teacher 08/03/2011

No thanks to Google! Nothing is clear - the expediency of this movement is simply indicated, but what is the mechanism? And why does rotation occur at night - does it mean there is memory or celestial navigation?

It's a delusion. He does not turn FOLLOWING THE SUN. It is constantly directed in the direction whose average daily brightness is greatest... Just like cucumber leaves in a greenhouse, just like indoor flowers on a windowsill.

Take a closer look. Both early in the morning, at dawn, and late in the evening at sunset, in an open field, the heads of sunflower flowers will be directed to the South. And in a shaded area - away from the shadow falling on it.

A series of experiments showed that the movement of sunflowers corresponds to a 24-hour circadian rhythm. Scientists tried to “deceive” the plants by artificially changing the duration of movement of the light source to 30 hours. However, in this case, the sunflowers moved unevenly, which affected their growth, biomass gain and yield.

It is known that sunflower inflorescences turn after the sun during the day, and at night they change their position again in order to “look” to the east at dawn. After sunflowers fade, they stop turning towards the sun.

Scientists explain that the movement of the sunflower inflorescence occurs due to the uneven growth of the plant. One side of the stem grows faster than the other, causing the inflorescence to turn.

In another experiment, scientists artificially limited the movement of plants. They tied some of the inflorescences so that they could not rotate, or turned the pots so that the plants were not facing the sun in the morning. It turned out that the leaves of both groups of sunflowers were 10% smaller than those of plants that followed the sun.

In addition to accumulating more biomass, sunflowers have acquired another advantage: plants facing the sun are much more attractive to insects. Five times more bees flew to flowers facing east in the morning.

“Bees go crazy for plants that face east, while ignoring flowers that face west,” says Stacy Harmer of the University of California, Davis. “On the sunny side, plants warm up faster, and warm flowers attract more pollinators.”

Anna Khoteeva

Fibonacci sequence discovered in sunflower flower

According to biologists, large flowers are one of the most obvious and beautiful demonstrations of the Fibonacci sequence. This number sequence is a series of natural numbers, where each subsequent number is equal to the sum of the previous two. The sequence might look like this: 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144…

The researchers found that the seeds are arranged in two rows of spirals, one of which goes clockwise, the other counterclockwise. According to scientists, in most sunflower inflorescences you can find a combination of numbers included in the Fibonacci sequence - for example, 34 and 55 or 55 and 89. And if you have a very large sunflower in front of you, then you can count 89 and 144 seeds.

In 2012, the Museum of Science and Industry in Manchester (UK), in honor of the centenary of the mathematician’s birth, launched an unusual project - “Turing’s Sunflowers”, inviting everyone to grow a sunflower and bring the flower to the museum (or send a photo of the plant).

This project allowed us to collect 657 photographs, the processing and analysis of which took almost four years. Since the seeds are usually clearly visible in the sunflower inflorescence, scientists were able to count their number and confirm that the Fibonacci pattern is indeed visible in the flowers.

Biologists cannot yet understand the mechanism behind the “adherence” of certain plants to numerical sequences. The problem is that plants don't always show this pattern. In the case of the sunflower flowers studied, seed patterns consistent with the Fibonacci sequence were found in approximately 80% of the plants. The remaining inflorescences showed more complex patterns.

Anna Khoteeva

Reference

British mathematician Alan Turing was interested in such patterns back in the first half of the last century. The scientist became famous for developing a method during World War II that helped crack the code of the German Enigma encryption machine. In addition, Turing had a significant influence on the development of computer science and artificial intelligence. After the war, the scientist became interested in mathematical patterns in plants.

August 5th, 2016 , 05:59 pm

People have long noticed that young sunflower flowers turn after the Sun during the day, and at night they return to their original position in order to meet it again in the east in the morning. What makes plants perform their daily ritual and why, over time, the “worship” of the luminary stops and mature sunflower flowers do not turn behind the Sun, but remain directed only to the east.

In search of an answer, Stacey Harmer of the University of California, Davis, and her colleagues conducted a series of experiments that confirmed the hunch that observing the Sun is necessary for sunflowers to grow more efficiently. Scientists fixed the plants, preventing them from turning, or, conversely, rotated the pots, disrupting the natural course of movement. In both cases, the leaves of the plants turned out to be about 10% smaller than those of their neighbors, who calmly turned behind the Sun.

In addition, experts placed several points on the stem with a marker to study how the sunflower moves behind the Sun. Scientists monitored the points using a video camera. If the distance between them changed, it meant that the flower stem was growing where these points were drawn.
When the plants turned to follow the Sun during the day, the eastern side of the stem grew at a faster rate than the western, causing the flower itself to turn toward the Sun. And at night, the western side grew faster, and the stem turned in the other direction.

The movement of the plant is carried out with the help of special motor cells that participate in the growth mechanism and are located in the flexible base of the flower. It turned out that this movement depended on the plant's internal clock - circadian rhythms that control various life processes associated with the onset of day, night, morning and evening. The "clock" controls the rate of growth and causes one side of the stem to grow faster than the other. Thanks to this, the sunflower gradually turns to follow the Sun.

As the sunflower matures and the flower opens, overall growth slows and the plants stop moving during the day, remaining oriented to the east. The fact is that the plant reacts more strongly to sunlight early in the morning than in the afternoon, so it gradually stops moving westward during the day.