Spraying crops with weed-killer is not only harmful to the environment, but it’s also costly for farmers. With those problems in mind, scientists have conducted a study which suggests that less herbicide could be used for the same results, if applied at the right time of day.
Just like us, plants have circadian rhythms. This means that throughout the day, their biological functions vary.
Because the same is true of humans, many medications work best when taken at a specific time, when the body is most receptive to their effect. Working with colleagues from Swiss agriculture tech company Syngenta, scientists from Britain’s University of Bristol set out to see if certain compounds – in this case harmful ones – would likewise be more effective when applied to plants at a given time.
In lab tests, they grew batches of a weed known as thale cress (Arabidopsis thaliana) under a 24-hour light/dark cycle, simulating the rising and setting of the sun. A commercial herbicide with the active ingredient glyphosate was applied to different groups of the plants, at different points within that cycle.
It was found that when administered at dawn, the glyphosate was most readily taken up by the plants. As a result, at that time of day, the herbicide had the most pronounced effect in both killing existing plant tissue and slowing subsequent growth. In order to have that same effect at different times, more of it had to be applied.
“This proof-of-concept research suggests that, in future, we might be able to refine the use of some chemicals that are used in agriculture by taking advantage of the biological clock in plants,” says Dr. Anthony Dodd, senior author of a paper on the research. “Approaches of this type, combining biotechnology with precision agriculture, can provide economic and environmental benefits.”
Plants’ “body clocks” may determine when herbicides work best [New Atlas]