HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Isbell, V. R. Articles by Morgan, P. W. Search for Related Content PubMed Articles by Isbell, V. R. Articles by Morgan, P. W. Agricola Articles by Isbell, V. R. Articles by Morgan, P. W.

Manipulation of Apical Dominance in Sorghum with Growth Regulators¹

The hormonal control of apical dominance (inhibition of lateral bud formation and development) in sorghum [Sorghum bicolor (L.) Moench] was studied by applying plant growth regulators to two cultivars—SM100 (weak apical dominance) and BTx378 (strong apical dominance). In the field, SM100 produced an average of 1 tiller per 2 plants before anthesis and BTx378 produced none. Following anthesis, apical dominance diminished in both cultivars. Spray applications of 0.2 mM gibberellic acid (GA₃) during the initial 7 weeks of seedling growth completely inhibited bud outgrowth before anthesis in SM100. Bud outgrowth increased rapidly in both cultivars after termination of GA₃ applications. This rapid increase in bud outgrowth was similar to the normal release from apical dominance ocurrlng in untreated plants following anthesis except that it was earlier, occurred at a more rapid rate, and a larger final number of buds was released. Thus, two aspects of the normal pattern of tiller bud development were mimicked by GA₃ application: i) intensification of the inhibition of bud outgrowth before anthesis and ii) acceleration of bud outgrowth occurring after anthesis. In plants grown hydroponically in the greenhouse, GA₃ again inhibited bud outgrowth in SM100 plants during the vegetative period. A role for gibberellin(s) in sorghum apical dominance is suggested because bud outgrowth was promoted in BTx378 plants by a gibberellin synthesis inhibitor, ancymidol. Evidence for the participation of auxins and cytokinins in sorghum apical dominance was also obtained. The auxin naphthaleneacetic acid inhibited bud outgrowth in SM100. In BTx378 the auxin transport inhibitor naphthylphthalamic acid and the cytokinin benzyladenine caused bud outgrowth which resembled that obtained by apical bud removal.

Key Words: Sorghum bicolor (L.) Moench • Tillers • Lateral buds • Plant growth regulators • Gibberellins • Auxins • Cytokinins

² Formerly, graduate assistant (present address Texas A & M Res. and Ext. Ctr., Lubbock, Tex.) and professor of plant physiology, Texas A & M Univ., College Station, TX 77843.

Received for publication September 29, 1980.

This article has been cited by other articles:

				J. M. Frantz, D. Pinnock, S. Klassen, and B. Bugbee Characterizing the Environmental Response of a Gibberellic Acid-Deficient Rice for Use as a Model Crop Agron. J., July 1, 2004; 96(4): 1172 - 1181. [Abstract] [Full Text] [PDF]