Studies Involving Sustained Treatment of Maize with Gibberellic Acid II: Responses of Plants Carrying Certain Tassel-Modifying Genes

Plants containing each one of seven different tassel-modifying genes were treated with Gibberellic Acid-distilled water mixtures every three days throughout the growing season until tassel emergence. GA was found to suppress expression of ramosa-1 (rai). Tassel-seeds 2 (ts2), 5 (Ts5) and 6 (Ts6), Tunicate (Tu) and Vestigial glume (Vg) were all modified, but not so much that they could not be recognized. The recessive male-sterile 1 (msi) remained male-sterile. An explanation of certain elongation patterns in these plants is tentatively made, which points toward the idea that GA depends at least in part on the presence of auxin (IAA) for its effects. NORTON H. NICKERSON, Missouri Botanical Garden, 2315 Tower Grove Ave., St. Louis 10, Missouri.