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FAIRBANKS - Researchers at the University of Alaska Fairbanks are reporting an encouraging sign for locally grown fruit - a robust apple crop.

The researchers in 2007 grafted 39 cold-weather apple varieties onto rootstock of the Ranetka crabapple, a Siberian tree known for its ability to withstand cold winters.

Half were placed in two "high-tunnel greenhouses" - giant hoop houses that offer a level of protection from the elements.

Fruit was harvested a year before expected.

"They're a little tart, but they're good," said research technician Kendra Calhoun as she bit into a tiny yellow Ukalskoje apple.

The project was developed by Cooperative Extension Service forestry specialist Bob Wheeler, who died in June. Wheeler was curious about the effect that the unheated high-tunnel greenhouses would have on the survival rates of apple trees and other fruit crops in interior Alaska, where temperatures drop to 40 below zero, or colder, most winters.

About 120 trees were planted inside the 96-by-42-foot open-ended greenhouses. Most are producing fruit that ranges in size from golf balls to grocery store variety fruit.

About 80 percent of the trees have survived their first two winters.

Trees outside the greenhouses are at least two weeks behind and many have not produced anything.

Jeff Werner, a research professor with the School of Natural Resources, helped take over the project after Wheeler's death. There are hopes that the system could allow rural Alaska communities to grow some of their own produce, he said.

The hoop cost about $5,000, although shipping boosts the cost.

"Ideally, if you can grow your food locally, that's what you want to do," Calhoun said.

Werner said the high-tunnel greenhouses also offset the "crazy long days" that some plants in interior Alaska do not tolerate well. For some plants, he said, better technology might be the key to getting better results.

"We've been looking for 100 years for the best green bean in Alaska," Werner said. "Maybe we need to use technology to grow them in a different way."

The end walls of the greenhouses are erected in mid-October to preserve heat inside. During winters, temperatures inside the structures averaged 10-15 degrees higher than outside temperatures. Soil temperatures were about 20 degrees cooler because no snow insulates the ground.

The formula seems to be a good one for apples but not other plants. Berries outside the high tunnels are doing better than the ones planted inside, Calhoun said.

The future of the program depends on finding a continued funding source. The project is being funded by a grant from the Western Sustainable Agriculture Research and Education Program.