© 2003 Heron Publishing—Victoria, Canada
Effects of induction treatments on flowering in Populus deltoides
Cetin Yuceer (1), Mark E. Kubiske (2), Richard L. Harkess (3) and Samuel B. Land, Jr. (1, 4)
1. Department of Forestry, Mississippi State University, Box 9681, Mississippi State, Mississippi 39762, USA / 2. Forestry Sciences Laboratory, United States Department of Agriculture Forest Service, 5985 Hwy K, Rhinelander, Wisconsin 54501,
USA / 3. Department of Plant and Soil Sciences, Mississippi State University, Box 9555, Mississippi State, Mississippi 39762, USA / 4. Author to whom correspondence should be addressed (sland@cfr.msstate.edu) / Received June 14, 2002; accepted October 26, 2002; published online April 1, 2003
Summary
Stimulation of early flowering is required to shorten breeding cycles of eastern cottonwood (Populus deltoides Bartr. ex Marsh. var. deltoides), a commercially important and fast-growing hardwood species. A series of experiments was conducted to evaluate the influence
of various treatments on flowering in rooted cuttings from mature and juvenile trees. A combined treatment of water stress,
root pruning and paclobutrazol was applied to 3-month-old rooted cuttings from mature trees. These cuttings had been subjected
to root restriction and long days. All treated plants flowered, whereas no untreated plants formed flower buds. One-year-old
rooted cuttings from juvenile trees did not flower when treated with either paclobutrazol, paclobutrazol plus water stress,
paclobutrazol plus root pruning, or paclobutrazol plus girdling. This was true both under continuous or periodic growth. Assessment
of the lack of flowering in juvenile trees may require an integrated approach that investigates environmental or physiological
stimuli, assimilate shift, gibberellic acid type and concentration, and flowering-time gene activity in the new shoots of
mature and juvenile cottonwood trees.
Keywords:
cottonwood, early flowering, girdling, juvenile, mature, paclobutrazol, precocious flowering, root pruning, water stress.
