Vol 124 (2011): Proceedings of the Florida State Horticultural Society
Citrus

Stimulating Flowering in Basal Buds of Sweet Orange Summer Shoots by Removal of Terminal Buds Early in the Flower Bud Induction Period

Eduardo J Chica
University of Florida, IFAS, Citrus Research and Education Center, 700 Experiment Station Road, Lake Alfred, FL 33850
L Gene Albrigo
University of Florida, IFAS, Citrus Research and Education Center, 700 Experiment Station Road, Lake Alfred, FL 33850
Published December 1, 2011
Keywords
  • Citrus sinensis,
  • floral induction,
  • inflorescence types,
  • tree size control.

Abstract

Under Florida conditions, most sweet orange flowers (≈80%) are formed in the four most apical buds of 1-year-old or younger shoots. Experiments were conducted to determine whether tip removal by clipping of the four most apical buds of 1-year-old sweet orange shoots before floral induction stimulated flowering in the remaining buds (more basal buds that do not usually flower). Clipped shoots had fewer buds starting growth in the spring and had fewer inflorescences than intact shoots. However, more buds started growth and more inflorescences were formed in clipped shoots than in buds at homologous positions in intact shoots (i.e., buds at position five or more below the original apex). The stimulation of basal buds to flower after clipping was stronger in ‘Valencia’ than in ‘Hamlin’ trees and greater when shoots were clipped in November (just before the onset of floral-inductive temperatures) than when shoots were clipped earlier in October or later in January. Clipped shoots produced more new vegetative shoots and formed inflorescences with a greater leaf: flower ratio than buds at homologous positions in intact shoots. These results indicate that removal of apical buds just before the onset of floral induction stimulates flowering at more basal positions of sweet orange
shoots. Results are discussed in relation to the potential application of this knowledge to minimize the impact of routine hedging and topping on flowering in Florida.