Effects of ethephon, ethylene, and 2,4-dichlorophenoxyacetic Acid on asexual embryogenesis in vitro.

Asexual embryogenesis in Daucus carota L. ;Queen Anne's Lace' callus was suppressed by Ethephon, ethylene, and 2,4-dichlorophenoxyacetic acid (2,4-D). The Ethephon effect could be attributed to volatile and nonvolatile substances. The volatile component was probably entirely ethylene. Ethylene was liberated in the cultures in direct proportion to Ethephon added to the medium. Autoclaving of Ethephon caused a substantial decrease of measurable ethylene. Continuous exposure of callus to 5 mul/l ethylene depressed somatic cell embryogenesis, but not markedly. Depression of embryogenesis by 2,4-D was unrelated to ethylene evolution.