Inhibition of Flower Initiation in Pharbitis nil by an Inhibitor of Steroid Biosynthesis is Dependent on Seedling Age

Abstract

Tris-(2-diethylaminoethyl)-phosphate hydrochloride (TDEAP), an inhibitor of cholesterol biosynthesis in animals, also inhibits flower initiation in Pharbitis nil when applied to the cotyledons prior to the beginning of the inductive dark period of a short day. TDEAP-induced inhibition of flower initiation is dependent, however, upon the age (or size) of the seedling treated. When the cotyledons are no more than half-expanded, 5 days after sowing, TDEAP-induced inhibition is observed clearly, but 5 days or more later when the cotyledons are fully expanded little or no inhibition is found. The most probable reason for the reduced sensitivity to TDEAP with increasing seedling age is that the capacity of the cotyledons and true leaves to synthesize the substances required for flower initiation increases with age.