Interaction of Growth-retarding Compounds and Gibberellin on Indoleacetic Acid Oxidase and Peroxidase of Cucumber Seedlings

Abstract

Several groups of growth-retarding chemicals have been reported in recent years. They belong to quite distinct chemical classes, but their effect on plant growth is similar. These include nicotinium compounds (31), quaternary ammonium carbamates (16), phosphonium compounds (37), choline analogues (42), and succinnamic acid derivatives (39). Unlike other types of growth inhibitors (e.g. maleic hydrazide) these compounds retard stem elongation without causing malformation of the plant. Their effects on plants are in many aspects opposite to those of gibberellin (3,42). Most of these inverse effects of the growth retardants and gibberellins are mutually antagonized when both chemicals are applied to the same plant (2, 3, 5, 7, 13, 14, 22, 27, 28, 41). It was therefore suggested (27, 42) that they be designated antigibberellins. This terminology has caused controversy. While Lockhart (27) concluded that a functional interaction exists between gibberellin and the growth retardants, Kuraishi and Muir (25) came to the conclusion, that these compounds do not interact directly with gibberellin, but rather with auxin. Stuart and Cathey (40) also felt that the growth-retarding chemicals should not be called antigibberellins. Our study presents data which are pertinent to this discussion.