title: Some Observations on the Effect of Gibberellic Acid on the Shape of Taraxacum officinale Leaf Primordia.
abstract: The effect of GA(3) on the leaf shape of T. officinale was studied by adding the hormone to the apical bud at a dose of 0.1 μg·d(-1) per plant. The allometric growth of the leaf was measured during the expansion as well as in the primordium stage of the 7(th) leaf. Results showed that GA(3) affected the final length-width ratio (L/W) of a leaf through an increase in the L/W ratio of its primordium, whereas the ratio was not changed during the succeeding expansion stage. GA(3) also affected the degree of leaf lobation. When plants with lobed leaves were treated with the same dose of hormone, the new leaves reverted to the juvenile (entire) shape, provided the primordia were shorter than 0.7 mm at the beginning of the GA(3) treatment. Histological studies of the primordia showed that GA(3) inhibited lobe formation by increasing the expansion of the interlobular zone of the leaf margin. The hormone also changed the number and size of epidermal cells.
authors.affiliation: Centro de Ecofisiología Vegetal (FECIC-CONICET-FUND. M. LILLO), Serrano 665, 1414 Buenos Aires, Argentina.
authors.forename: D H
authors.initials: DH
authors.lastname: Cogliatti
authors.forename: M R
authors.initials: MR
authors.lastname: Guitman