© 1994 Heron Publishing—Victoria, Canada
Floral induction in Eucalyptus nitens
M. W. Moncur (1) and O. Hasan (2)
1. CSIRO, Division of Forestry, P.O. Box 4008, Canberra, ACT 2600, Australia / 2. Cooperative Research Center for Temperate Hardwood Forestry and Department of Plant Science, University of Tasmania, GPO Box
252C, Hobart, Tasmania 7001, Australia / Received January 3, 1994
Summary
Eucalyptus nitens (Deane & Maiden) Maiden takes at least five years to initiate flower buds from seed and is an infrequent and light flowerer.
Because this behavior constitutes a major impediment to breeding programs, we examined the mechanisms controlling floral induction
in E. nitens, with the long-term aim of reducing generation time and increasing seed yield.
Application of paclobutrazol reduced the concentration of endogenous gibberellic acid (GA) in apical tissue and enhanced the
reproductive activity of grafted trees maintained outside over winter in Canberra, Australia. Grafts maintained in a warm
greenhouse over winter did not produce flower buds, despite the paclobutrazol-induced reduction in GA concentration of the
apical tissue. Exposing untreated grafts, which had been maintained over winter in a warm greenhouse, to low temperature the
following spring reduced growth but did not induce flower bud production. Addition of GA3 to paclobutrazol-treated grafts reduced the effect of paclobutrazol on reproductive activity.
Keywords:
flowering, generation time, gibberellins, low temperature, paclobutrazol, seed yield.
