VIENNA, Austria -- Pierre Lagoda pulled a small container from his pocket and spilled the contents onto his desk. Four tiny dice rolled to a stop. "That's what nature does," Lagoda said.

The random results of the dice, he explained, illustrate how spontaneous mutations create the genetic diversity that drives evolution and selective breeding.

He rolled the dice again. This time, he was mimicking what he and his colleagues have been doing quietly around the globe for more than a half-century -- using radiation to scramble the genetic material in crops, a process that has produced valuable mutants like red grapefruit, disease-resistant cocoa and premium barley for Scotch whiskey.

"I'm doing the same thing," he said, still toying with the dice. "I'm not doing anything different from what nature does. I'm not using anything that was not in the genetic material itself."

Lagoda, the head of plant breeding and genetics at the International Atomic Energy Agency, prides himself on being a good salesman. It can be a tough act, however, given wide public fears about the dangers of radiation and the risks of genetically manipulated food.

The process leaves no residual radiation or other obvious marks of human intervention. It simply creates offspring that exhibit new characteristics.

Plant scientists say radiation breeding could play an important role in the future. By promoting crop flexibility, it could help feed billions of added mouths despite shrinking land and water, rising oil and fertilizer costs, increasing soil exhaustion, growing resistance of insects to pesticides and looming climate change. Globally, food prices are already rising fast.

"It's not going to solve the world food crisis," said J. Neil Rutger, former director of the Dale Bumpers National Rice Research Center in Stuttgart. "But it helps."

The atomic agency in Vienna has promoted the method since 1964 in outreach programs with the Food and Agriculture Organization of the United Nations, in Rome.

Starting roughly a decade ago, for instance, the atomic agency helped scientists fight a virus that was killing cocoa trees in Ghana, which produces about 15 percent of the world's chocolate. The virus was killing and crippling millions of trees.

In the city of Accra on the Atlantic coast, at the laboratories of the Ghana Atomic Energy Commission, the scientists exposed cocoa plant buds to gamma rays. The mutants included one that endowed its offspring with better resistance to the killer virus.

The scientists planted the resistant variety on 25 farms across Ghana "with no evidence of a resurgence," M.R. Appaih, executive director of the Cocoa Research Institute of Ghana, told the agency.

The atomic agency had similar success in the Peruvian Andes, where some 3 million people live on subsistence farming. The region, nearly two miles high, has extremely harsh weather. But nine new varieties of barley improved harvests to the point that farmers had surplus crops to sell.

In Vietnam, the agency has worked closely with local scientists to improve production of rice.  One mutant had yields up to four times higher than its parent and grew well in acidic and saline soils. Last year, the nation had sown the new varieties across more than 1 million hectares, or 3,860 square miles.

New York Times News Service

The crop mutants
Though poorly known, radiation breeding has produced thousands of useful mutants and a sizable fraction of the world's crops, including varieties of rice, wheat, barley, pears, peas, cotton, peppermint, sunflowers, peanuts, grapefruit, sesame, bananas, cassava and sorghum. The mutant wheat is used for bread and pasta and the mutant barley for beer and fine whiskey.

The mutations can improve yield, quality, taste, size and resistance to disease and can help plants adapt to diverse climates and conditions.

"Spontaneous mutations are the motor of evolution," Lagoda said in his office. "We are mimicking nature in this. We're concentrating time and space for the breeder so he can do the job in his lifetime. We concentrate how often mutants appear - going through 10,000 to 1 million - to select just the right one."

Radiation breeding is widely used in the developing world, thanks largely to the atomic agency's efforts. Beneficiaries have included Bangladesh, Brazil, China, Costa Rica, Egypt, Ghana, India, Indonesia, Japan, Kenya, Nigeria, Pakistan, Peru, Sri Lanka, Sudan, Thailand and Vietnam.

When it began 80 years ago

The method was discovered some 80 years ago when Lewis J. Stadler of the University of Missouri used X-rays to zap barley seeds. The resulting plants were white, yellow, pale yellow and some had white stripes -- nothing of any practical value.

But the potential was clear. Soon, by exposing large numbers of seeds and young plants, scientists produced many more mutations and found a few hidden beneficial ones. Peanuts got tougher hulls. Barley, oats and wheat got better yields. Black currants grew.

The process worked because the radiation had randomly mixed up the genetic material of the plants. The scientists could control the intensity of the radiation and thus the extent of the disturbance, but not the outcome. To know the repercussions, they had to plant the radiated material, let it grow and examine the results. Often, the gene scrambling killed the seeds and plants, or left them with odd mutations. But in a few instances, the process made beneficial traits.

Today, about half the rice grown in California derives from this dwarf. Today, the process usually begins with cobalt-60, a highly radioactive material used in industrial radiography and medical radiotherapy. Its gamma rays, more energetic than X-rays, can travel many yards through the air and penetrate lead.