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Plant Science, Biotechnology, & Agriculture

Slideshow: Brookhaven and the Gamma Field

In the 1950s, Brookhaven scientists induced mutations in plants by bombarding them with radiation. They hoped this would lead them to a better understanding of genetics – and perhaps create useful new varieties of familiar plants.

black and white aerial photograph of a field with concentric circular furrows, surrounded by woods
This photograph shows Brookhaven’s Gamma Field from above, with the area that was cultivated in 1952 marked in pen. In the center of the circle, you can see the radiation source, a mass of cobalt-60 that could be raised to irradiate the field, or lowered into a lead and concrete-lined pit so that workers could enter the field. The control house is visible above and to the left of the circular irradiated area, with the dirt road leading to the radiation source in the center. Source: University of Virginia Special Collections. Used with permission.
black and white photo of a man standing in a cornfield between a section of tall corn plants and a section of of short ones
Brookhaven corn geneticist W. Ralph Singleton stands between standard corn (left) and his short corn (right), produced through a combination of traditional breeding methods and irradiation. Singleton and his colleagues hoped that such a plant would increase agricultural yields because it produced these same amount of grain but required less space and energy — Singleton had effectively increased the plant’s ratio of grain to everything else. In addition, it would be easier to harvest. Ultimately, the project was never commercialized. Part of the problem was that the short corn was not resistant to common plant diseases. Singleton and his team spent years trying to integrate the genes that made these plants short into disease-resistant commercial hybrids, but without success. This type of project, using radiation to modify agricultural plants with the goal of increasing yield and improving other aspects of the plant, was one of the primary goals of radiation breeding programs like Brookhaven’s. Source: University of Virginia Special Collections. Used with permission.
image of many opaque black circular pollen grains and a few transparent, shriveled ones
This is pollen from a normal corn plant with no exposure to unusual levels of radiation. Note that most of the grains are uniform, round and opaque. Source: University of Virginia Special Collections. Used with permission.
irregular and misshapen pollen grains, many of them semi-transparent and shriveled
This is pollen from a plant growing in Brookhaven’s gamma field. Note that there are many irregularly formed gains, the grains are of different sizes, and some of them are only partially opaque. Many are broken. Corn geneticists at Brookhaven discovered that the best time to irradiate corn was after the pollen had formed and before it was shed. If corn was exposed to high doses of radiation during the process of cell division that created pollen, the plant would produce nearly no functional pollen. Since this pollen is from a plant that was growing in the gamma field, and thus would have been exposed to radiation constantly — including as its pollen formed — what we can see here is pollen with very few functional grains. Source: University of Virginia Special Collections. Used with permission.
a male scientist points to ears of corn mounted on a white card, with a photo of a field in the background
Corn geneticist W. Ralph Singleton shows four ears of corn that were grown in the gamma field. From left to right, the plants that produced these ears received 230, 113, 54, and 27 roentgens per day. The effect of the highest dose on the ear on the far left is easy to see. In the background, there is a photograph of the gamma field. In the late 1940s and early 1950s, scientists did not yet know in detail how much radiation was necessary to cause various types of damage to plants, animals or people — the gamma field experiment at Brookhaven was part of the process of finding this out. The pollen from corn plants like these, that had been grown in the gamma field, was used to pollinate plants in non-irradiated fields in order to study to the heritable effects. Source: University of Virginia Special Collections. Used with permission.
black and white image with a black tangled line a gray egg-shaped blob
A document accompanying the original of this photo of corn chromosomes explained what the photograph shows, according to the scientific understanding of the 1950s:
“The dark strands in this photo are the 10 chromosomes in a single cell of a tassel, the male flower of the corn plant. Some 200 to 300 genes, the units which transmit heredity characteristics, are strung like beads along the 10 chromosomes. The blurred oval in this view through a microscope is the nucleolus, or ‘organizer’ of chromosomes in a cell.

The photograph is part of a study at Brookhaven National Laboratory, Upton, N.Y., of mutations, or changes, caused in corn heredity by exposure of plants to x-rays. The black specks on the chromosomes are gene sites, which may be affected by radiation. Frequently radiation causes breaks in chromosomes. Recombinations results in a mutant plant which differs from normal, producing changes in plant height, ear size, plant color, and so on. In this case a large dose (2000 roentgens) of radiation caused no breaks in the chromosomes. However, radiation did change a gene site, and the plant mutated to a condition called glossy, in which the plant leaves have a glossy or waxy appearance.

Corn is frequently used in genetics studies because its chromosomes are large enough to be observed easily under a microscope, and because a great deal of information has been gathered about corn genes. As a result, corn breeders have made considerable progress in improving plant strains, and geneticists have assisted in broadening the understanding of mechanisms of heredity.”

Source: University of Virginia Special Collections. Used with permission.
postcard showing aerial view of a field with concentric circular furrows
This postcard is filed among materials relating to an international genetics conference in 1953. That Brookhaven produced postcards of its gamma field suggests the importance of the apparatus as well as its visual interest. The circular rows of plants radiating outward from the cobalt-60 source in the center was a striking illustration of the power of atomic energy and the resources Brookhaven had invested in exploring it. Plus, it was a form of advertising directed at scientists at the conference who might not know that they could collaborate with Brookhaven and make use of its plant irradiation equipment. Source: University of Virginia Special Collections. Used with permission.
magazine clipping with a row of images of potatoes with various levels of sprouting
Brookhaven scientists Arnold H. Sparrow and Eric Christensen used varying doses of radiation to see whether this stopped potatoes from sprouting and if it helped preserve them longer in storage. Their work showed promise, as this illustration from Nucleonics suggests (Nucleonics was a nuclear science trade journal published between the late 1940s and the late 1960s.) Potatoes were an important cash crop on Long Island through the middle of the twentieth century, farmers were always interested in finding ways to store them more effectively. Source: Nucleonics Magazine. Used with permission.

Plants need nitrogen to grow, but a significant portion of the nitrogen in fertilizers is not absorbed by the soil or used by the growing plants. Rather, it washes away into waterways, rivers, and the ocean. This in turn has had devastating effects on marine life. In some areas, excessive nitrogen in the oceans has caused algae blooms that kill wildlife, make it dangerous for people to consume fish or shellfish or in some cases even swim in affected waters. This problem isn’t limited to poorer countries. Nitrogen pollution is a serious problem here on Long Island. In our case, the nitrogen comes primarily from septic tanks and cesspools, although nitrogen from agricultural fertilizers also plays a role. Nitrogen pollution in the waters around Long Island has hampered fishing, made it dangerous to eat seafood from some areas, and caused environmental changes that make coastal areas more prone to flooding.