The Ecological Impact of Certain Nonherbicidal Growth Regulators

Abstract

The environmental hazards involved with the use of the growth regulators, ethephon and endothall in combination, have been examined and found to be minimal. Ethephon was absorbed by the roots in nutrient solution causing a 507 growth inhibition at 0.5 - 1.0 mg/liter. Translocation of ¹⁴C-ethephon was evident throughout the plant 4 hr. after foliar application. No exudation of radioactive material from the roots of foliarly treated plants was detected. Untreated companion plants located adjacent to treated plants showed no epinasty, abscission or growth inhibition over a 7-day period in soil or nutrient solution. The ethylene evolution from 84 µMoles of ethephon in phosphate buffered solution, pH 6.5, attained a maximum rate of about 950 41/liter per hour after one day. Addition of endothall did not alter exudation of ethephon or ethylene evolution. Possible ecological hazards involved with large scale applications of endothall-ethephon are assessed by projection of the laboratory results.