A robot with steely hands is a big help in the garden or plowed field. What's more, it could change agricultural systems.
That is, a research team led by Richard Hassell at Clemson University has developed a robotic system that does the tedious work of grafting, or joining two plants so they grow as one. In this case, the system joins strong and disease-resistant roots to thriving plant tops - combining two good halves.
"Grafting has been done all over the world for about 60 years, but when done by hand, it's very slow and labor-intensive," noted Hassell. His team includes Mark Schaffer, Brian Ward, Manning Rushton and Ginny DuBose. "The robot does it much faster than a human can do it. This reduces labor costs while at the same time enhancing healthy and robust growth because the same clean cut is made every time."
Grafting allows us to put together the best parts of two plants. "The reason we graft crops such as watermelons, cantaloupes, tomatoes and peppers is because they have poor root systems that are very susceptible to soil-born disease. And so anything in the soil that stresses their roots collapses the plants," Hassell said. "But if we graft hardier resistant rootstocks from plants such as gourds and squash onto the shoots of the desired crop, then the fruit-producing part of the plant is able to thrive."
A 2014 patent from the Hassell team worked on a related problem: regrowth. This takes place because the rootstock that has been grafted to a new top tends to try to produce its own shoots and leaves. Then the grafted upper area of the new plant dies.
The group of scientists headed by Hassell dealt with this by using a chemical known to control tobacco plants' tendency to grow suckers. The latter would stick to surfaces and slow the plant's growth.
"We worked out the dilution and application methods and now we are able to destroy the growing point of the rootstock, which eliminates regrowth," said Hassell. "We treat the root stock chemically as soon as it comes up and its first leaf appears. We call it blinding. The plant is actually blinded and has no growing point anymore."
At that point, the robot can seize and slice a watermelon's upper shoot along with a gourd's rootstock and join the two together. Then the joined plant is set for its new life.
"Grafting was laughed at when I first came here," commented Patrick Wechter, a plant pathologist at the U.S. Vegetable Laboratory. "People said no one will ever do it in the U.S. because it's too expensive. But Richard has persisted and become of one of the leading experts in the world on grafting."
Additional reporting by Catherine Arnold.
