Light Signals From Neighbouring Weeds Alter Crop Growth, Yield: U of G Research

In the battle between weeds and crops, weeds are winning. Weeds are resilient and adaptable and can damage crop yields. A new theory developed by a University of Guelph researcher suggests why. For the first time, plant scientists have shown that weeds can alter crop plant growth from a distance by affecting light signals used by the crop plants to communicate.  

For the past 20 years, Dr. Clarence Swanton, a weed scientist in the Department of Plant Agriculture at the Ontario Agricultural College, has sought to answer why crop yields still decline when weeds no longer pose a threat.  

Current understanding of plant competition is based on the limitation of resources of light, water and nutrients available to plants.  

Swanton doesn’t dispute that aspect, but he and colleagues at the United States Department of Agriculture (USDA) bring something new to the table. In the presence of weeds, crop plants become so stressed out that they change their chemical and physical behaviour, the researchers write in Trends in Plant Science.  

The paper introduces a new paradigm of plant competition, one that could increase crop tolerance to weeds while producing more food and reducing agriculture’s environmental footprint, and hints at the next steps needed to transform the theory into practice.