© 1994 Heron Publishing—Victoria, Canada
Maturation in Douglas-fir: II. Maturation characteristics of genetically matched Douglas-fir seedlings, rooted cuttings and
tissue culture plantlets during and after 5 years of field growth
Gary A. Ritchie (1), Steven D. Duke (2) and Roger Timmis (2)
1. Weyerhaeuser Company, G.R. Staebler Forest Resources Research Center, 505 North Pearl Street, Centralia, WA 98531, USA / 2. Weyerhaeuser Company Technology Center, Federal Way, Tacoma, WA 98003, USA / Received February 23, 1994
Summary
Seedlings, rooted cuttings from juvenile stock plants, and cotyledon-derived tissue culture plantlets were propagated from
several coastal Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) full-sib families so that the rooted cuttings and plantlets were clonally identical. The stock types (seedlings,
rooted cuttings and plantlets) were planted in the field in spring 1987. In fall 1991, after five complete growing seasons,
the plants were measured and these values compared to maturation “markers” identified for Douglas-fir in the companion paper
(Ritchie and Keeley 1994). Nodal branch lengths and nodal branch diameters decreased in the order seedlings > rooted cuttings
> plantlets. The decreases were about 21% for nodal branch lengths and 24% for nodal branch diameters. Seedlings carried significantly
more total branches (nodal + internodal) than the other two stock types. Height growth was similar for the three stock types,
but plantlet height increment was beginning to decrease during the fourth year. We conclude that vegetative propagules of
Douglas-fir exhibited traits of mature trees. These were particularly marked in the cotyledon-derived plantlets.
Keywords:
clonal forestry, juvenility, organogenesis, Pseudotsuga menziesii, tissue culture.
