By Sharon Omahen
University of Georgia
Outside of the holidays, sweet potatoes tend to be a forgotten vegetable, mentally packed away with the decorations. Bob Jarret, though, thinks about them all the time. He can call most of the 700-plus varieties by name.
Jarret is a sweet potato curator at the U.S. Department of Agriculture Plant Genetic Resources Conservation Unit in Griffin, Ga. Basically, his job is to make sure none of these sweet potatoes becomes extinct.
Providing germplasm for breeding
"The primary reason we maintain all these lines is to provide plant material for scientists," Jarret said. "Researchers are always in need of certain traits to make a new variety better than the existing one. One variety may not taste very (good), but it's valuable because it's resistant to pests or drought."
The sweet potato weevil, for instance, shut down production in Georgia in the early 1990s. "If a variety was bred to be resistant to this weevil, farmers could avoid this problem in the future," he said.
Most of the requests Jarret gets are from scientists. About 10 percent, though, come from home gardeners.
"Most people are searching for the kind they ate as a child or the kind their grandfather grew," he said. "Many grew up on a farm and know the name of the variety."
The older varieties are usually just as nutritious as the newer ones, he said, but aren't as attractive.
"The flesh isn't as brilliant orange," he said. "There have been a lot of improvements made over the years in physical appearance and yield."
Jarret says the most popular varieties on the market today are Beauregard and Jewel. "I can usually tell by looking whether or not it's a Beauregard," he said. "The flesh is a very bright orange."
This description fits the bill for the atypical sweet potato, but not the entire USDA collection.
"Some of the varieties in our collection have sweet roots and some have roots that aren't too sweet," he said.
Not just for eating anymore
Jarret says people like sweet potatoes now for more than their nutrition.
"More and more people are looking at sweet potatoes as ornamental plants," he said. "They want something unique that their neighbors won't have."
Some sweet potato varieties have uniquely colored or variegated leaves. The USDA collection in Griffin, though, doesn't include ornamental varieties.
"I've seen a lot of these popping up in local nurseries," Jarret said. "They make attractive pot plants, but I wouldn't try to eat the roots."
Stored as little plantlets
To protect the hundreds of edible sweet potato varieties, Jarret grows plants and removes small cuttings called plantlets. These are stored in coolers and replenished every six months.
He also stores breeding material for peppers, watermelons, squash, okra, eggplant and a few other plants like bottle gourds and luffas.
"I maintain them today to assure they're around tomorrow," Jarret said.
For more information on the USDA National Plant Germplasm System, see their Web site at www.ars-grin.gov/npgs/.
(Sharon Omahen is a news editor with the University of Georgia College of Agricultural and Environmental Sciences.)