ABSTRACT
A large number of observations on the effects of ethylene on vegetative growth have been made since the discovery of the hormonal effects of this gas. This chapter focuses on the effects of ethylene on the vegetative growth of dry land and semiaquatic plants with the emphasis on the cellular mechanisms of ethylene action. Ethylene-induced closure of the hook region of monocot and dicot seedlings is also based on the ability of ethylene to selectively inhibit cell growth on the inner part of the hook. One of the earliest mentioned effects of ethylene on the etiolated seedlings of dicotyledon plants is the loss of geotropism reviewed. The discovery that certain cyclic olefins, most notably 2,5-norbornadiene, are specific and reversible inhibitors of ethylene action provided tools for examining the effects of endogenous ethylene on vegetative growth. A similar explanation may apply to Avena sativa, where ethylene is capable of promoting tiller release from apical dominance.
