Sunflowers ‘dance’ to optimize growth, Israeli-US study reveals

A new study has uncovered a collective growth strategy employed by sunflowers in dense environments in which the flowers engage in a "dancing" movement, Tel Aviv University said on Tuesday.

The study revealed that sunflowers use random movements to optimize their growth directions, allowing them to avoid shading each other and maximize sunlight exposure.

This discovery can shed light on a long-standing scientific question regarding the functional role of circumnutations, a type of cyclical movement observed in plants, Tel Aviv University said.

The study was led by Prof. Yasmine Meroz from the School of Plant Sciences and Food Security at Tel Aviv University's Wise Faculty of Life Sciences in collaboration with Prof. Orit Peleg from the University of Colorado Boulder.

The research team also included Dr. Chantal Nguyen from Boulder, Roni Kempinski, and Imri Dromi from Tel Aviv University. Their findings were published in the journal Physical Review X.

Previous studies have shown that sunflowers planted in high-density fields grow in a zigzag pattern to avoid casting shadows on each other.

This growth pattern allows them to maximize sunlight capture for photosynthesis on a collective level. Sunflowers can distinguish between the shadow of a plant and the shadow of a non-plant object, such as a building, and alter their growth direction accordingly.

How was the study conducted?

According to the study, the team conducted experiments in a controlled laboratory environment, growing sunflowers in close proximity and capturing their growth with time-lapse photography. The resulting footage revealed that the sunflowers exhibited a "dancing" behavior, with each flower moving randomly in search of the best angle to avoid shading its neighbors.

This phenomenon was first observed by Charles Darwin, who noted that plants exhibit cyclical movements during growth, known as circumnutations.

While this behavior has been recognized for over a century, its functional role has remained unclear, except in specific cases like climbing plants. The current study provides new insights into the significance of these movements, demonstrating that they play a critical role in optimizing collective growth, Tel Aviv University said.

The researchers quantified the sunflowers' movements through physical analysis and computer simulations. They found they varied widely in scale, ranging from minimal displacement to movements of up to two centimeters every few minutes.

These random movements help minimize mutual shading among the sunflowers, thereby enhancing their ability to capture sunlight.

The range and randomness of these movements are crucial for minimizing shading and maximizing photosynthesis. Tel Aviv University concluded that this can provide new insights into the adaptive strategies plants use to thrive in competitive environments.