COLUMBUS, Ohio - An automated image scanning system developed to assess overall seed vigor of lettuce has been refined to measure half of all seedling plant varieties that exist and is nearly 80 percent accurate.
The system, developed by Ohio State University crop production and computer science researchers, is more rapid and accurate than manual tests and improves upon existing commercial automated systems. Initially designed to measure seed vigor of lettuce plants because of their simple root structure, the system can now assess seed vigor of soybeans and cotton and has the capabilities of measuring seedlings of plant varieties from crops to grasses to ornamentals.
"This is just an invaluable piece of technology," said Miller McDonald, an OSU seed scientist. "Farmers want good seed in their fields. If it's not good seed, the plant won't grow. This system tells you how fast a seed grows and how uniformly it grows, and that's the bottom line." Seed companies conduct rigorous stress tests on seed varieties, including cold tests and accelerated aging tests, to determine which varieties have the highest percentage of germination, hence providing farmers and greenhouse growers the best opportunities for a larger yield. In the past, these tests were conducted by hand, a time-consuming, laborious and often faulty process. McDonald and other researchers were interested in developing a system that improved upon the manual tests.
The image scanning system combines an inverted flatbed scanner that records digital images of germinating seeds with a computer that then processes the data and gives a quantitative measurement of overall seed vigor. The process eliminates the need to conduct stress tests by hand. The system can calculate overall seed vigor within three to four days of germination as opposed to seven to 14 days if tested by hand.
The researchers believe the system is also an improvement upon existing commercial tests, which only examine certain seedling parts, such as root length or the cotyledon (the part of the seed that produces the plant's first leaves). The new system has the capabilities of measuring all seedling parts, providing more accurate and reproducible seed vigor data. It measures growth of the seed; the roots; and the hypocotyl, or the plant stem located just below the cotyledon. A numeral index of zero to 1,000 (zero indicating poor germination and 1,000 indicating ideal germination) is given to each plant part, and then a final number is given for the seed variety that identifies its overall vigor.
"We wanted to develop technology that will benefit the seed industry. With this system, seed companies can provide their customers with more accurate germination information, and hence, the highest-quality seed lot," said McDonald.
The refinements to the image scanning system have enabled researchers to classify the seedling being measured based on its root and hypocotyl structure. For example, lettuce seedlings are classified as type "I" because the roots generally grow in a straight line.
OSU horticulturist Mark Bennett said that the researchers believe most plant seedlings fall under the 'I' category. "We feel that 40-50 percent of plant species fall under the 'I' type classification. With the right software, we envision this system to eventually be able to measure nearly all seedling types," he said.
The seedling classification will make it easier for seed companies to evaluate overall seed vigor, since some seedling root and hypocotyl structures, like corn and soybeans, are not so clear cut as lettuce. "It was pretty challenging for us to try to measure soybean seedlings," said McDonald. "Unlike lettuce, there is no clear demarcation line in soybeans that separates the root and hypocotyl from the cotyledon." McDonald added that when measuring overall seed vigor, it's important to focus completely on the growing root and hypocotyl and eliminate the cotyledon, since it provides no information regarding seed vigor. "If we leave any part of the cotyledon in the measurement, you'll get an erroneous result," he said. "It's important to be able to distinguish where the root and hypocotyl end and the cotyledon begins." The researchers believe that the image scanning system is an advantageous piece of technology for both farmers and seed companies.
"Farmers want their seed to come up as soon as possible. The soil is a hostile environment. The quicker the seed comes up, the better chance the plant has to survive," said McDonald. "Also, farmers want uniform growth, especially when they need to spray their fields." Added Bennett, "It's the same for the greenhouse plug industry. Companies want all of their plug cells to sprout plants. Any plant that doesn't come up is lost revenue for them." Seed companies can also benefit from the image system in that it can assist them in moving inventory - ridding seed that has gone bad, selling a better product by being able to identify which seeds grow the quickest or which ones can withstand stress, and modifying orders to fit specific customer requirements.
"Its uses are endless," said McDonald. "And the best thing about the system is that is establishes a uniform standard of seed quality." The researchers are still fine-tuning the image system. They are currently working on developing software that will measure corn and grasses, and are working with various seed companies to test the unit in the field. They expect to have the system patented by early next year.