Plants Can Make Decisions, Too

A research team at the University of Tübingen in Germany explained that plants reach a tacit agreement with neighboring plants when they feel pressured by competition. The study also found that plants respond to the size and density of nearby plants to find ways to survive.

According to a study published in Nature Communications, plants choose one of three responses: outcompeting their rivals by growing taller, maximizing shade tolerance—the ability to withstand low-light conditions—or growing in a different direction from neighboring plants to avoid competition.

The researchers used cinquefoil plants to create various scenarios to which the plants could adapt. Using vertical strips of transparent green filters, they adjusted the amount of light absorbed and wavelengths ranging from red light to near-infrared. Plants use these wavelengths to detect how much sunlight neighboring plants are filtering out.

Researcher Michal Gruntman said, “Through this study, we wanted to find out how plants determine the size and density of neighboring competitors and what choices they make.”

The cinquefoil underwent a series of tests in which it was surrounded by small plants as well as by large plants.

The researchers found that the cinquefoil grew vertically when surrounded by small plants but switched to a shade-tolerance mode when placed next to large plants.

The researchers sought to test their hypothesis that plants would grow sideways to avoid competition when surrounded by large plants.

The researchers said they would investigate whether such decisions also apply to other factors, such as root growth.

Gruntman said, “The ability to choose a response is particularly important in environments where multiple plant species coexist. In such environments, plants must select an appropriate strategy because they have to live alongside plants of various sizes, ages and densities.”