With corn being a critical U.S. crop expected to help feed livestock and people around the world and also be a source for the production of clean energy, plant breeders are continually seeking ways to make the plants more productive. To better understand the role corn roots play in this regard, an agricultural engineer and a crop scientist at the University of Illinois at Urbana-Champaign have teamed up to examine corn root complexity and how it impacts corn development.
"Corn root structure is very complex, and it is critical to the growth of the plant," says Martin Bohn, University of Illinois associate professor of crop sciences. "Only with an efficient and well-developed root system can the crop produce the high yields producers are looking for and meet world demand."
Tony Grift, University of Illinois associate professor of agricultural and biological engineering, is partnering with Bohn to examine corn root systems and to evaluate differences among corn genotypes. The team has developed innovative technology that uses high-resolution images of corn roots and statistical software to evaluate root complexity.
The 'softbox' imaging tool they designed assures proper light penetration into the corn roots and automatically acquires six images per root at the click of a mouse button. These images are then analyzed using a statistical software program to generate a value for root complexity. The highly automated procedure stores the data in a library containing tens of thousands of images. This allows revisiting the imagery when new measurements or methods are developed.
"We define root complexity as the number of root branching points," Bohn says. "For the human eye, it's virtually impossible to meaningfully evaluate these differences in root systems. Very importantly, we are looking at the root structure of plants grown in actual soil in the field. Previous methods have examined the root complexity of plants grown in artificial environments, such as through hydroponics. The root systems we look at better represent what actually happens in the field."
According to the researchers, a complex root structure could lead to a more productive plant. "Root systems with a greater number of branching points allow the plants to be more efficient at taking up water and nutrients from the soil," Bohn explains.
The software analysis employed to evaluate the root systems uses fractal dimensions — a statistical evaluation of geometrical shapes — to provide an indirect estimate of the number of branching points. Not only does the analysis of the roots provide an estimate of root complexity, it also allows the researchers to correlate differences in the complexity of the root systems with the plants' genetic makeup.