THE ROLE OF GIBBERELLINS IN THE CONTROL OF INFLORESCENCE BUD INITIATION OF RHODODENDRON SIMSII

Three different GAs (GA₁, GA₃ and GA₄) and two growth retardants (paclobutrazol and cimectacarb-ethyl) were applied directly on the apical buds of Rh. simsii grown in 16-h days.
All 3 GAs stimulated shoot growth and inhibit the inflorescence bud initiation.
At similar concentrations, they act differently : GA₁ promotes leaf initiation to a small extent, while GA₃ and GA₄ stimulate both leaf initiation and internode elongation.
The inhibition of the inflorescence bud initiation is directly related to the promotive effect of GAs on shoot growth.

Paclobutrazol reduces leaf initiation and internode elongation, but promotes inflorescence initiation.
Cimectacarb-ethyl inhibits both internode elongation and inflorescence initiation.

The possible role of specific GAs in the control of the shoot development of Rh. simsii will be discussed.

Workshop on Environmental Regulation of Plant Morphogenesis

M. BODSON, E. THOMAS

shoot growth, internode elongation, GA₁, GA₃, GA₄, paclobutrazol, cimectacarb-ethyl, growth retardants

https://doi.org/10.17660/ActaHortic.1995.378.15