STUDIES OF NECTAR SECRETION IN EXCISED FLOWERS: II. THE INFLUENCE OF CERTAIN GROWTH REGULATORS AND ENZYME INHIBITORS

Publisher Website
Google Scholar
Abstract
Concentrations of 5 × 10−5 M to 5 × 10−4 M of 3-indoleacetic (IAA), α-naphthaleneacetic, or 2,4-dichlorophenoxyacetic acid usually reduced nectar secretion in excised flowers of Antirrhinum majus L. cultured on sugar solutions. The major part of the reduction occurred at relatively low concentrations of the growth regulators. The percentage reduction by IAA remained fairly constant when the sugar concentration of the medium was varied. Although the growth-regulating compounds promoted ovary growth, increased growth did not appear to have been the cause of reduced nectar yields. IAA sometimes increased nectar secretion. The effect of IAA on secretion was modified by 2,3,5-triiodobenzoic acid. Nectar secretion was partially inhibited by iodoacetic acid, sodium arsenate, dinitrophenol, sodium azide, and fluoroacetic acid at concentrations which caused no visible injury to flowers. Two inhibitors of phosphate transfer, dinitrophenol and sodium arsenate, modified the influence of IAA. The data support the hypothesis that nectar secretion is an active process.