Factors affecting the activity of ethephon in stimulating seed germination of <i>Striga hermonthica</i> (Del.) Benth.

Abstract

Summary Ethephon (2‐chloroethylphosphonic acid), which generates ethylene, stimulated the germination of pre‐conditioned seeds of Striga hermonthica when it was added to the alkaline Gezira clay soil at concentrations of 2.5 to 30 mg kg −1 . As little as 5 min contact with treated soil was enough to stimulate germination. Ethephon in soil did not cause germination of unconditioned seeds for periods of up to 12 days and also had an adverse effect on seed germination when such seeds were given a second ethephon exposure after a storage period which was adequate, in untreated soil, to give the necessary pre‐conditioning. Ethephon activity persisted in air‐dry soil but declined over a 14 day period in moist soil. In the field ethephon at 0.6 to 4.8 kg ha −1 decreased the number of Striga shoots and increased sorghum height and flowering.