Weeds have potential to reduce crop yields by affecting the light signals plants use to communicate, according to scientists in Canada.
Direct competition for light, water and nutrients are typically considered the main causes of weed-induced yield losses.
But an analysis of research from researchers at the University of Guelph suggests weeds interfere with light signals crop plants send out before they even emerge from the soil.
This disruption prompts the crop plant to alter the way it grows, ultimately causing yields to be reduced — even if the weeds are subsequently removed.
In a review published in Trends in Plant Science, the research team explained that as well as depending on light to grow and photosynthesise, plants use light to communicate and detect if they’re surrounded by siblings or competitor plants.
If the crop plant detects any stressors, it changes its own chemical make-up and the way it grows.
Depending on the stage of crop growth that these changes occur, the crop plants yields can be impacted significantly and quickly — with weeds that emerge early in the crop plant’s live having the greatest impact on productivity, the researchers wrote.
While there is considerable research that confirms plants communicate with one another using light signals, the scientists said the next step is to identify the genes and molecules that allow plants to percept those signals.
“The ability to manipulate [them] could be avenues for developing cropping systems where crops are partially or completely blind to weeds, especially early in their growth cycle,” they wrote.
However, since some of those processes are required to protect the plant from predation, diseases, and other stresses, additional research will be needed to identify methods to specifically block the signals only when weeds are present, they said.
“Crops that are less responsive to competitors may also have reduced yield losses when grown with cover crops or in intercropped systems,” they added.
“Thus, development of weed-tolerant crops might also help reduce the impact that climate change is predicted to have on increasing weed pressure in cropping systems.”
