Any material used on plants or animals to kill insects or disease organisms must pass rigid inspection to be sure it does not accumulate in foodstuffs. This is particularly true of the “systemic” poisons, those which are fed to plants via leaves or roots and are carried internally to all parts of the plant. Such chemicals can be used widely with nonfood plants such as cotton to kill insects feeding on them.
Combining radioactive labeling with other techniques has permitted the researchers to show that some compounds are soon broken down into harmless chemicals—a big step toward acceptance for their use on food plants.
Radioisotopes as Radiation Sources
Earlier in this booklet radioisotopes were compared to fireflies because they emit flashes of “light.” Isotopes serve research in another important way, other than as tracers.
Suppose you collected all the fireflies within a 100-mile radius and put them into a glass jar. Instead of an occasional twinkle, you would now have a steady glow of light. Similarly immense numbers of radioactive atoms can be compressed into a small volume to produce steady, intense sources of radiation. Agricultural research has answered many questions with the use of such radiation sources.
Can Radiation Produce New Plants?
Perhaps no biological aspect of atomic energy has so caught the fancy of the public as the prospect of creating new plant varieties. There is something mysterious about pouring invisible energy into seeds or buds and watching for changes in the emerging leaves and flowers. There is also the challenge of the lottery in being unable to predict where, when, or in what form the alterations will appear.
Although the claims of over-enthusiastic gardeners and seed dealers about astonishing new plants “created” by atomic radiation are doubted, clear proof exists even in the restrained scientific journals of hereditary changes caused by radiation.
From more than 30 years of scientific study, certain conclusions have emerged. High-energy radiations can cause sudden hereditary changes (mutations) in any living thing: man, animal, microbe, or plant. Any feature of a plant subject to hereditary control—root, shoot, leaf, flower, or fruit—can be altered by radiation. Most of these changes are undesirable; they interfere with the normal state of biological affairs. A very small percentage of mutated organisms is improved in some way. So far changes cannot be controlled or predicted.
To date fourteen new strains of crop plants improved by radiation have been put into production in various parts of the world. These varieties with their places and dates of release follow: