(Aminooxy)acetic acid inhibits petunia growth and gibberellin- and cytokinin-stimulated growth in bioassays

(Aminooxy)acetic acid (AOA) was applied to greenhouse-grown petunias and was used in bioassays for three plant growth hormones so that its growth regulator properties could be studied. In greenhouse studies foliar sprays of 4.8–12 mm AOA inhibited vegetative growth of petunia seedlings (Petunia xhybrida Vilm. White Flash). When gibberellin A ₃ (GA₃) was applied to shoot tips previously treated with AOA, plant growth was stimulated, but there was no AOA x GA₃ interaction. Some changes in petunia leaf morphology induced by AOA were reversed by GA₃. AOA inhibited elongation of corn coleoptile segments (Zea mays L. B73 x Mol7) whether or not 10 m indole-3-acetic acid (IAA) was present, but there was no AOA x IAA interaction. AOA reduced lettuce hypocotyl (Lactuca sativa L. Grand Rapids) elongation induced by GA₃ and radish cotyledon (Raphanus sativus L. Champion) expansion induced by benzyladenine (BA). We propose that AOA interferes with postsynthetic metabolism of plant hormones during cell elongation induced by GA₃ and cell expansion induced by BA.Abbreviations AOA (aminooxy)acetic acid - GA₃ gibberellin A₃ - IAA indole-3-acetic acid - BA benzyladenine