The Rio Red grapefruit was bred from irradiated seeds to produce its characteristic color.

A Short History of Atomic Gardening

Hunger, profits, and Atoms For Peace have driven attempts to alter crops with radiation, chemicals, and genetic manipulation.

In the early 1920s, Lewis Stadler, a crop scientist at the University of Missouri, began zapping maize and barley with X-rays. When the barley was planted and began to grow in a new range of colors, some with stripes, it was clear that there was something strange going on deep inside the plant. Mutation breeding has featured somewhere on the agricultural and scientific landscape for nearly a century since. Popularized in the wake of the Second World War as “atomic gardening,” researchers blasted seeds with gamma rays, ion beams, and electrons, or subjected them to a variety of chemical mutagens. In most cases, the process involved exposing seeds to radioactive cobalt-60 in hazardous cabinets or special fields arranged in a ring around a radiation source, with different crops laid out in wedges emanating from the center. While the plants closest to the radiation source mostly died, those beyond, which received lower doses, grew with new and occasionally interesting traits. Those that appeared to show bigger yields, hardier crops, or other desirable characteristics were cultivated.

Mutagenesis was one plank of the U.S. Atoms for Peace initiatives during the Cold War that proposed peaceful uses of atomic technologies while pursuing the U.S. goal of nuclear containment. In the United Kingdom and the United States, there was a fad for quaint atomic gardening societies, citizen organizations that made local headlines with oversized peanut plants and elephantine tomatoes. In the book Evolution Made to Order, science historian Helen Anne Curry records how entrepreneurs like mail-order seed salesman David Burpee contrived marketing ploys for irradiated marigolds called “X-Ray Twins.” His ambition was to “shock Mother Nature,” he said.

By the mid-century, rapidly developing nations from Egypt to Pakistan had growing populations to feed and were screening hundreds of thousands of plants that had been zapped with radiation. For countries with enough arable land and cheap labor, this kind of experimentation makes economic sense, explains Ranjith Pathirana, a research fellow for Plant & Food Research Australia, who began working with mutagenesis in his native Sri Lanka almost 40 years ago. The Soviet Union, too, was an enthusiastic adopter after its belated embrace of genetic science, and radioactive Gamma Kolos towers filled with cesium-137 were left littering the landscape at the fall of communism. (They were more recently the subject of a fearful treasure hunt across former Soviet republics in the aftermath of 9/11, as the U.S. government raised fears the radioactive matter could be turned into a “dirty bomb.”) For agricultural states whose governments, unlike the U.S., typically develop crops centrally and distribute seeds widely to farmers, it was a model that worked to ensure crops developed higher yields and desirable traits, said Pathirana, who earned his PhD in Moscow before returning to Sri Lanka. 

In 1964, the United Nations food and nuclear power agencies, the Food and Agriculture Organization (FAO) and the International Atomic Energy Agency (IAEA), agreed to merge their mutation breeding projects, becoming the chief global sponsor of mutagenesis. “The FAO/IAEA division has been funding developing countries to develop these programs,” says Pathirana, whose colorful career breeding mutant sesame, peanuts, and rice took him to nuclear facilities the world over, and ensured he would forever struggle to pass through airport security. At least 3,365 mutant varieties are registered in the FAO/IAEA Mutant Varieties Database, each listing a beneficial modification to one of 220 crops coming from 70 countries. China has at least 200 more, according to FAO/IAEA. 

Many of these were developed for responses to particular challenges. In a 2007 interview, FAO/IAEA plant breeding chief Pierre Lagoda recounts a virus that was killing cacao trees in Ghana that was halted when a virus-resistant mutant was bred using gamma rays. In Vietnam, the agency helped breed a mutant rice that grew better in acidic and saline soils, where it produced four times higher yields, helping feed subsistence farmers. 

“For these places where you’re fighting for food security and yield stability under the pressures of climate change, mutation breeding is very, very critical.”

During this time, a few shopping basket mainstays have appeared from radiation-induced mutagenesis: The deep red grapefruit Rio Red was bred from irradiated seeds to produce its characteristic color, and it accounts for about three-quarters of all grapefruit now grown in Texas. A sticky, medium-length rice called Calrose 76 was bred to be short and easily harvested by combine, becoming the most common rice variety now grown in California. An Australian researcher bred Linola, a flaxseed mutant that produces a fatty acid composition very similar to olive oil and used it to create a butter-like spread, among other food products. Drink, as well as food, changed: A high-yielding type of barley named Golden Promise was so popular during the 70s and 80s that “any whiskey aged between 35-40 years old today will more than likely have come from it,” according to according to Bill Thomas, a barley geneticist at the James Hutton Institute in Scotland.

As transgenic technologies started making big strides in the 70s and 80s, allowing researchers to produce so-called genetically modified organisms (GMOs), these scattershot, random mutation breeding experiments took a backseat to their GMO rival, which allowed scientists to rationally engineer traits. GMOs achieved remarkable results focused on yields, insect resistance, and herbicide resistance, “So that industrial farming is possible without weeding,” says Shoba Sivasankar, head of plant breeding and genetics at a joint FAO/IAEA division. 

An aerial picture of a Gamma Garden still in tact in Japan.
A Gamma Garden at the Institute of Radiation Breeding in Hitachiohmiya, Japan. Google, Maxar Technologies, Map data @2021

But it remains popular in the Asia-Pacific region, Sivasankar adds, where it continues still. Mutagenesis remains important “in places—Asia-Pacific, in Africa—where we are fighting to improve yield for food security, improve nutrition,” she explains. “For these places where you’re fighting for food security and yield stability under the pressures of climate change, mutation breeding is very, very critical.”

Looking around the grocery store shelves or the farmer’s field in the West today, there is little genetic innovation that matches the breakneck pace of GMO transgenic technology. It rolled out across U.S. fields in the 1990s, and by 2015, in the United States, 94 percent of soybeans planted and 92 percent of cotton were GMO. So mutagenesis did not change the world we live in or the fields we farm in. Despite the optimism of the postwar period, there are just a few reminders, says Curry: “Here and there, there are crops on the landscape that people point to and say, ‘This is an example of a variety created through mutation breeding, which produced a trait or a quality that was particularly useful or beneficial or marketable.’”

Go Deeper