Plants can make complex decisions says new study

Berlin: Plants can choose between alternative competitive responses according to the stature and densities of their opponents, a study has found. Researchers from the University of Tubingen in Germany found that plants can evaluate the competitive ability of their neighbours and optimally match their responses to them. Plants can detect the presence of other competing plants through various cues, such as the reduction in light quantity or in the ratio of red to far- red wavelengths ( R: FR), which occurs when light is filtered through leaves. Such competition cues are known to induce two types of responses: confrontational vertical elongation, by which plants try to outgrow and shade their neighbours, and shade tolerance, which promotes performance under limited light conditions. Some plants, such as clonal plants, can exhibit avoidance behaviour as a third response type: they grow away from their neighbours, researchers said. “These three alternative responses of plants to light competition have been well- documented in the literature,” said Michal Gruntman, lead author of the research published in the journal Nature Communications. The researchers used the clonal plant Potentilla reptans in an experimental setup that simulated different lightcompetition settings. They used vertical stripes of transparent green filters that reduce both light quantity and R: FR and could therefore provide a realistic simulation of light competition. By changing both the height and density of this simulated vegetation, the researchers could present different light- competition scenarios to the plants. The results demonstrated that Potentilla reptans can indeed choose its response to competition in an optimal way. When the plants where under treatments simulating short- dense neighbours, which presented competitors that where too dense to avoid laterally but could be outgrown vertically, Potentilla reptans showed the highest confrontational vertical growth. However, under simulated tall- dense neighbours, which could not be outgrown either vertically or laterally, plants displayed the highest shade tolerance behaviour.