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The poplar is hardy and quick-growing, traits that make the tree an ideal farm crop for reforestation and the biofuel industry.

Phenotype Screening Corp. (PSC) of Seymour, Tenn. — a company run by University of Tennessee alumni Dan McDonald and Ron Michaels — has studied which varieties of these trees root the quickest and grow the fastest. The company has received help along the way from four UT professors and the Center for Industrial Services (CIS), an agency of UT’s statewide Institute for Public Service.

PSC was created by McDonald, an electrical engineer who retired from Oak Ridge National Laboratory (ORNL), and Michaels, who has a doctorate in engineering science and formerly ran an industrial X-ray company in Seymour. The two set out to fill a research void by inventing a system that could measure plant root systems accurately without destroying the plants. In 2004, McDonald and Michaels won a grant from the U.S. Department of Energy to develop the plant X-ray system.

McDonald said a variety of environmental pressures are fueling interest in plant studies, and PSC’s root X-ray system is likely to play a key role in future research.

“A growing world population, climate change, scarcity of water and the need for renewable sources of energy are among the factors that will change the way we grow plants, as well as the types of plants we grow,” he said. “Food, feed, fiber, fuel, housing, pest control, environmental preservation — they all rely on our ability to grow plants better, faster and more efficiently.”

In May 2006, PSC began an eight-month project, funded by an $80,000 grant from the U.S. Department of Agriculture, to study poplar and willow trees, two trees used in the biofuel industry. Research partners included UT, the U.S. Forest Service, ORNL and State University of New York’s College of Environmental Science and Forestry.

Bill Wiley and Jim Slizewski of CIS helped PSC link up with four UT professors to provide them with the critical scientific expertise. CIS provided matching funds and eliminated some of the overhead expenses associated with working with the professors.

“With the financial assistance we could provide, we quadrupled the amount of work they were going to be able to do,” Wiley said.

PSC researchers study crops in Styrofoam-like containers. Instead of soil, the company uses low-density polymeric foam that is disease- and pest-free. While regular soil would absorb the X-rays, the containers and the synthetic soil are transparent to X-rays.

These containers fit into low-energy digital X-ray machines which the company designs and builds. The X-ray machines are connected to computers that allow an operator to manipulate the plant and container, snap X-ray pictures, then put the pictures together like a puzzle. Traditional X-ray images and 3-D X-ray images are possible.

The company’s X-ray system doesn’t damage the plant, so researchers can X-ray the same plant many times as it matures to study its root development and monitor how different nutrients, water and growing conditions affect its growth.

In the tree study, PSC looked at six types of poplars and four types of willows.

“There is a lot of interest in using poplar and the willow trees as energy crops because of their fast growth, ability to reduce greenhouse gasses and high energy-out to energy-in ratio,” McDonald said.

“Fast-growing hybrid poplars also are grown on plantations in many areas for pulpwood, used for the manufacture of paper, and as a direct source of wood chips for burning in electrical power plants. It is also sold as hardwood timber, used in chip board manufacture and for furniture applications.”

UT Associate Professor Zong-Ming “Max” Cheng, a plant physiologist, helped the company by developing a way to get test-tube poplar trees to grow in the synthetic soil. Associate Professor Neal Eash’s soil science lab studied the company’s artificial soil and compared it to natural soils to see how similarly they held and drained water. Professor Roberto Benson, a materials scientist, helped them develop a process to dissolve their synthetic soil, so that the remaining root system could be extracted and measured using traditional methods in order to calibrate the X-ray method; and Research Assistant Professor David Page, a computer vision expert, helped the company reduce the “noise,” or extraneous details, from the X-ray images to get a picture of the roots without clutter from the moisture or the artificial soil.

“Those four scientists are each world-class researchers, and we were able to attain a slice of their time,” McDonald said. “Their expertise was critical for our work.”

Trees are only one crop PSC is studying, and the expertise provided by the UT professors will carry over to multiple projects. The company’s other projects involve corn, rice, soybeans, squash, sweet potatoes, sorghum, bluestem grasses, switchgrass and pine trees.


Dan McDonald, cell-(865) 385-8641, mcdonalddw@phenotypescreening.com

Amy Blakely, (865) 974-5034, amy.blakely@tennessee.edu

Bill Wiley, (865) 974-8464, wwiley@utk.edu

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