According to legend, a Canadian farmer found the mutant cauliflower in his garden. There was no mistaking it. It was orange--not just a tad off-color, not just a peach blush. No, it was orange. Like a Caribbean sunset.

"The plant breeder who gave me the seed said the farmer grabbed it out of the field and gave it to an extension agent [or its Canadian equivalent], who gave it to a scientist," said molecular biologist David Garvin. That was 30 years ago.

Garvin, who works for the Agricultural Research Service, is looking for the genetic trigger that enables the mutant to produce 500 times as much of the nutrient beta-carotene as regular cauliflower. "It still tastes the same," he said.

This year, with a budget of $834 million, the Agriculture Department's research arm is maintaining about 100 different labs around the country, including Garvin's. If you can grow it and sell it, then somewhere ARS is working on it.

ARS is not small-time. These are the scientists who invented frozen orange juice, permanent-press cotton and potato flakes, and who first mass-produced penicillin.

But these days, the research menu is longer. Bioengineering has given new significance to onetime curiosities such as Garvin's cauliflower. The quest for "value-added" agricultural products has led to new uses for yesterday's throwaways. And antipollution laws have made environmentalism a business necessity.

At the ARS's Plant, Soil and Nutrition Laboratory in Ithaca, N.Y., Garvin is searching for the cauliflower mutation gene because beta-carotene is an important source of Vitamin A and has properties that may reduce the risk of some types of heart disease and cancer. Finding a "gatekeeper" gene in cauliflower, Garvin hopes, will enable him to mutate other crops that people "will eat more readily."

At the Appalachian Fruit Research Station in Kearneysville, W.Va., ARS horticulturist Richard Bell has already used a soil bacterium gene to grow about six dozen dwarf Bosc pear trees, which are 18 months old and about one-fourth the size of normal trees.

He hopes the trees will be a squat eight feet tall with fewer branches, but with normal-sized fruit. Plant them six feet apart instead of the usual 12, and the grower will enjoy breakthrough yields.

It will take a couple of years "to determine whether the degree of dwarfism will be economically useful," said Bell, who worries that his trees are too small. It's no good if the itty-bitty tree produces itty-bitty fruit.

Although biotechnology may be research's leading edge, ARS has many projects based on rethinking old knowledge, finding uses for the formerly useless, or just exploiting simple country hunches.

ARS soil scientist Henry F. Maryland, for instance, knew that plants accumulate starches and sugars during sunny days, so that forage is much richer in nutrients at dusk than at dawn.

But "I wondered if animals could tell the difference," said Maryland, a researcher at ARS's Northwest Irrigation and Soils Research Laboratory in Kimberly, Idaho.

So he cut grass and alfalfa in the morning and in the afternoon, and dried and shipped the samples to ARS researchers in North Carolina to give to cattle, sheep and goats. Every diner made a beeline for "the p.m. hay."

Now, he said, "we'd like to find out what they're cuing on," but that's extra. By harvesting at dusk, farmers can improve nutrient content by 15 percent to 30 percent, which "is worth $1 million per cutting of alfalfa in California," Maryland said.

Another easy moneymaker appears to be Central American corn, which is becoming the forage of last resort in the American Southeast when unseasonable cold weather delays the spring planting of domestic corn.

In the past, dairy farmers substituted sorghum, but "cows don't like sorghum," and discontented cows eat less and give less milk, said plant physiologist Joseph Burns of the ARS plant research unit in Raleigh, N.C.

But they like Central American corn. "You can plant it later, grow it through a dry spell in June or July, and cut it for silage in early October," Burns said.

Better still, Central American corn grows faster in the United States because summer days are longer at higher latitudes. Its yield per acre is 15 percent lower than that of U.S. corn, Burns said; otherwise farmers might forget about U.S. corn altogether.

Plant peculiarities are also what prompted ARS scientists at the Appalachian Farming Systems Research Center in Beaver, W.Va., to focus on the lowly chicory, a sometime salad green and a bitter additive that makes weak coffee seem stronger.

It turns out that chicory, with a deep taproot and a highly developed fibrous root system, loves nitrogen and phosphorus. "Just slurps it up," said animal research scientist Kenneth E. Turner.

This is not necessarily a good thing, since nitrogen and phosphorus are agriculture's two most important plant nutrients, but in a fertilized forage field, chicory acts as a policeman. The grass uses the nitrogen it needs, then chicory's deep taproots suck up the excess before it runs off as contaminated groundwater.

Other low-end products with newfound uses are nutshells, which ARS research chemist Wayne Marshall is studying as a source of "granular activated carbons" to cleanse factory effluent of organics or heavy metals.

Coconut shells and coal are industry's usual carbon filters, but these are expensive, at least relative to nutshells, which nut processors "just want off the property," Marshall said.

At ARS's Southern Regional Research Center in New Orleans, Marshall heats shredded nutshells and pits them with acid so they look like tiny asteroids. A one-gram piece of shell can have up to 900 square meters of surface area.

Hard shells, such as walnuts, hazelnuts, pistachios and especially macadamias, are great for leaching benzene, acetone and other organics, Marshall said, although he doesn't know why. Soft shells--almonds and pecans--are preferred for metals such as lead, cadmium and mercury.

For the latest in waste management, though, research leader Patricia D. Millner at the Soil Microbial Systems Laboratory at ARS headquarters in Beltsville has high hopes for pasteurized manure.

Millner is experimenting with a closed-bin system pioneered for sewage treatment by a Toledo-based firm, N-Viro International. It uses an auger to mix manure with a high-alkaline waste product such as lime kiln dust, coal ash or cement dust.

The resulting reaction generates enough heat to kill E. coli, Cryptosporidium parvum, salmonella and other pathogens and breaks the mix down into ammonia gas and a dry, grayish, odorless, alkaline substance that serves as "a good starting point" in building soil in an acidic environment, Millner said. "You're using two byproducts to make one useful product."

CAPTION: ARS scientists are seeking the genetic trigger that makes the mutant orange cauliflower, top, rich in beta-carotene, a nutrient. They also are studying the use of chicory, above left, as a "biological sponge" to absorb excess nitrogen and phosphorus from soils. Above right, Blake's Pride, a fire blight-resistant pear that the ARS introduced in 1998.

CAPTION: ARS developed the sweet Bluebyrd Plum, which is named for Sen. Robert C. Byrd (D-W.Va.).