Learning more about how crop plants communicate – especially under competition from weeds – is the goal of University of Guelph research funded by Food from Thought.
Dr. Clarence Swanton, a weed scientist in the Department of Plant Agriculture within the Ontario Agricultural College, studies how corn and soybean plants interact and communicate.
More important, he’s looking at how weeds affect that communication as well as the physiology and yield potential of crop plants. To compete with weeds, plants need to expend energy that they would normally use to grow and produce.
“The detrimental changes to the plant – including the suppression of photosynthesis and the expression of free radicals and oxygen – are irreversible to the crop,” Swanton says.
“Up to now, competition has meant for light, water, nutrients and space, but we asked, what if there’s more to it than that?”
He and his team have discovered that the mere presence of a weed – even one that’s not touching a corn plant – can affect how nitrogen is distributed in the plant.
The secret lies in light
“It has to do with far-red light signals with which the plants detect their neighbours,” he says.
To observe how plants interpret those light signals, the researchers placed potted crop plants and weeds near one another and gave them adequate space, light, water and nutrients. For comparison purposes, potted crop plants were grown in exactly the same way but had no weeds nearby.
The results were intriguing
During the research, the corn growing near weeds stopped mobilizing nitrogen.
“It’s a very subtle form of communication in which a crop plant can detect a neighbour plant and determine whether it’s a competitor and, if so, gets stressed and reduces its yield potential,” he says.
These previously unreported mechanisms mark a new understanding of how plant communities are shaped, says Swanton. They also help explain why it’s so important to control weeds in the field early.
He says researchers might ultimately design crop plants that are more tolerant of weeds. “If we could shift the yield loss curve so that it’s slower and later, it would have a significant impact on agronomy,” he says.
While crop plants may not become completely tolerant of weeds, this research “would definitely make a big difference in terms of sustainable crop production,” he says.
He says the work may further enhance crop production in Canada and adds that it is garnering attention from researchers around the world.
The U of G plant scientist is ranked seventh in Canada by Research.com for his impact in plant science and agronomy.