The Use of Ethephon to Regulate Sex Expression of Summer Squash for Hybrid Seed Production1

Abstract

Abstract Recommended rates of (2-chloroethyl)phosphonic acid (ethephon) application did not prevent staminate flower formation on summer squash ( Cucurbita pepo L.) sufficient to permit hybrid seed production without defloration. The field experiments were conducted in commercial fields in which flower development occurred during warm long day conditions, which promote maleness in squash. A strongly female ‘Cocozelle’ inbred, a strongly male ‘Straightneck’ inbred and a very strongly male ‘Crookneck’ inbred were treated at several seedling stages with rates up to 600 ppm ethephon. Two applications of 400 to 600 ppm ethephon resulted in development of the fewest staminate flowers without significantly reducing seed yield or quality. The ‘Crookneck’ inbred was least responsive to ethephon.