Ethylene and carbon dioxide in the growth and development of cultured radish roots

Ethylene is produced by cultured radish roots in amounts large enough to be physiologically important. When roots were grown in controlled atmospheres, applied ethylene was generally inhibitory to elongation, lateral root initiation, and cambial activity. 1% CO₂ similarly affected roots not given ethylene. In contrast, elongation and lateral root production of ethylene-treated roots were stimulated by 1% CO₂. The results suggest that the often-observed stimulation of root growth by CO₂ is due to an interaction with endogenous ethylene.