Colouring crops to weed out weeds

Farmers have long been wrestling with the question: how do you weed out the weeds from the crops? With 8 billion mouths to feed and climate change to wrestle with, we need to make farming far more efficient and a lot more sustainable. So scientists like the University of Copenhagen’s Michael Palmgren have been looking at ways to cut chemical use by making crop plants far easier for robotic farmers to tell apart from the nuisance weed seedlings they need to remove…

Michael - Agriculture is looking forward to some tough times because we have more mouths on this planet that has to be fed and at the same time climate change will maybe make lower yields. Another problem that we face are the weeds because many weeds are very resilient. So if the predicted climate change scenarios come, then we will maybe have weeds that are much tougher than the crops we grow. So the weeds will take over. So how do we compete with the weeds? One solution is of course to use herbicides, but in a sustainable agriculture you don't want to use any herbicides or pesticides or as little as possible. So a solution could be to develop new resilient crops that can be detected at a very early stage, mechanically not by chemicals.

Chris - So you are saying in order to make agriculture more efficient, what we should do is have plants that are easier to grow because we can get a machine to spot and tell apart weeds from plants we do want and rather than use enormous doses of chemicals, we would just weed them out mechanically.

Michael - That would be a sustainable solution. If we can find ways to detect weeds at an early stage before they grow too big and then beat them out mechanically.

Chris - How would we do that then? How could we mark or earmark plants that we do want so that machines are better at telling what we do want from what we don't want?

Michael - There are reading robots now that are quite good at taking out weeds between plants and in some cases they can also have sensors. So they can detect weeds that look very different from the crops. They can move around in the fields like a lawnmower. But the problem comes when the weeds look very much like the crops that we grow, especially at a very early stage. Our proposed solution is to introduce mutations into our crops or newly developed crops that makes them distinguishable, maybe not by the naked eye, but from a robot trained by sufficient intelligence that has specific sensors that can detect these subtle changes. And we have several examples for what you could do and not by introducing new genes, just by making mutants.

Chris - I presume that to make those subtle changes that would just give a crop plant a characteristic that a robot could spot easily. That's what you're advocating for, isn't it? That must be a lot easier to do than to try to engineer into a crop plant some other trait.

Michael - Yes, and a new trait can develop even from a small mutation. So for example, leaf shape can change from a mutation. That could be one trait that you modify slightly the leaf shape at an early stage, but also colour. And the colour doesn't need to be something you can see with your naked eyes. It could be a colour that only specific sensors can detect.

Chris - And if this were to come to fruition, what sort of a difference to agricultural productivity and solving some of those things you highlighted earlier would this make?

Michael - It would contribute to a more sustainable agriculture and less use of chemicals and would open up the field for making new crops developed from wild plants, but can now be used as food stuff.