© 1990 Heron Publishing—Victoria, Canada
Crown architecture of Populus clones as determined by branch orientation and branch characteristics
Reinhart Ceulemans (1, 2), R. F. Stettler (1), T. M. Hinckley (1), J. G. Isebrands (3) and P. E. Heilman (4)
1. College of Forest Resources, University of Washington, AR-10, Seattle, WA 98195, USA / 2. Department of Biology, University of Antwerpen, B-2610 Antwerpen (Wilrijk), Belgium / 3. USDA Forest Service, North Central Forest Experiment Station, P.O. Box 898, Rhinelander, WI 54501, USA / 4. Western Washington Research and Extension Center, Washington State University, Puyallup, WA 98371-4998, USA /
Summary
Crown architecture, including branching pattern, branch characteristics and orientation of proleptic and sylleptic branches
was studied in five poplar clones (Populus deltoides, P. trichocarpa and P. trichocarpa × P. deltoides hybrids), grown under intensive culture in the Pacific Northwest, USA. Branch characteristics measured were number, length,
diameter, biomass and the angles of origin and termination. The results suggest that genotype has a major influence on crown
architecture in Populus. Clonal differences in branch characteristics and branching patterns were found that resulted in striking differences in
crown form and architecture. Branch angle and curvature differed significantly among clones, and among height growth increments
within clones. Branch length and diameter were significantly correlated in all clones. Sylleptic branches and the considerable
leaf area they carry have important implications for whole tree light interception, and thus, play a critical role in the
superior growth and productivity of certain hybrid poplar clones. The considerable variation in branch characteristics implies
a strong justification for including them in selection and breeding programs for Populus.
