COLUMBUS, Ohio — The delicate nature of promoting the use of ornamental plant germplasm and preserving seed for the future lies in time and accuracy. The quicker, more efficient the process, the more beneficial it is to the floriculture industry.
Ohio State University's Ornamental Plant Germplasm Center (OPGC) has taken its role of saving and assessing germplasm beyond traditional boundaries to become one of the few sites in the world to explore the use of medical x-ray technology in seed science.
"The traditional way to determine if a seed lot is viable or not is to perform a germination test," said David Tay, OPGC Director. "Though effective, germination tests are tedious and time consuming, taking anywhere from a couple of weeks to a couple of years, depending on the seed dormancies involved. Sometimes we just don't have that amount of time to test and process seed."
The OPGC recently acquired a digital tabletop radiography unit to help weed out empty, damaged and diseased seeds from viable ones. Tay said that it only takes about 20 seconds to produce a computerized digital x-ray image from which the seeds can then be analyzed.
"With most seeds, it is instantly obvious which ones are good and which ones are not going to germinate," said Tay. "With the good seeds, you can see the thick, plump embryo filling the seed coat. With the bad seeds, the embryo is small and shriveled, or is simply not present."
Tay said that the machine is just as accurate as germination tests when it comes to sorting viable seeds from empty and damaged seeds. Additionally, the effect of the low radiation on the seed, up to 60 repeated treatments, does not impact seed quality when germination is done immediately, according to research conducted by Tay and his students, graduate student Toddy Hu, of horticulture and crop science, and natural resources undergraduate Russell Eckley. Researchers are analyzing the impact of radiation following long-term seed storage.
Researchers at the OPGC have found a variety of uses for the x-ray technology. One such use is as an added step in the seed cleaning process.
"We use the machine frequently when cleaning seeds. Machines, like blowers and shaker tables, separate the lighter, emptier seeds from the heavier, good seeds," said Susan Stieve, OPGC seed crop curator. "The x-ray machine is good for determining when you've crossed over from blowing out dead seeds to removing seeds which are good, but happen to be smaller and lighter. It allows us to clean seeds to a very high level of quality without sacrificing good seed in the process."
Researchers also use the unit to detect seed damage invisible to the naked eye.
"For example, we are able to instantly see hairline cracks in seed and separate those from undamaged seed," said Tay. "Additionally, the x-ray machine can also pinpoint insect activity inside the seed that we obviously wouldn't be able to see looking at the outside of the seed coat."
The OPGC, located on the campus of Ohio State's College of Food, Agricultural, and Environmental Sciences, is a joint effort between the university and the USDA Agricultural Research Service. To date, over 3,000 accessions of herbaceous ornamental plants have been collected for conservation and used for research. For more information on the OPGC, log on to http://www.opgc.osu.edu.