National Geographic : 1953 Aug
) National Geographic Society 212 Kodach A Atomic By-products Find Peacetime Uses in Agricultural Research This underground growth chamber duplicates sun light artificially. By following the movement of "hot" tracers-radioactive isotopes-absorbed with fertilizers, scientists can analyze the feeding and growth processes of plants. romes by National Geographic Photographers John E. Fletcher and Donald Mcllain 4 Light, Visible and Invisible, Controls the Life Cycle of Plants Beltsville learned that the varying duration of dark ness and the color of light control plant behavior. Using a giant spectrum, H. A. Borthwick (left) and S. B. Hendricks discovered that red light retards the flowering of some plants; infrared promotes it.