IntensIve sIlvIculture - Forest Science Labs - Research Network ...

Keywords: nursery operations
tree morphology
tree/stand health
Abstract: The effectiveness of 6 indole-3-butyric acid (IBA) and four 1-napthaleneacetic
acid (NAA) concentrations, 4 combinations of IBA and NAA concentrations, and control were
tested for their ability to enhance rooting frequency of Douglas-fir [Pseudotsuga menziesii]
cuttings. Two IBA and one NAA treatments were also compared to the control for quality of root
system. Between 1984 and 1998, six independent studies were conducted in mist or fog
environments with the 14 clones. Auxin concentrations tested ranged from 0 to 123 mM IBA and
0 to 10 mM NAA. Auxin, clone and auxin by clone effects were significant in every study,
although individual clone analyses showed only two clones to differ significantly for auxin. All
auxin treatments except the 10 mM NAA treatment induced significantly greater rooting
percentage than the control, but no single auxin, auxin concentration or combination of auxins
was clearly superior in every study. The 10 mM NAA concentration was the only concentration
tested that reduced rooting percentage to less than the control. Both NAA and IBA appeared to
have broad ranges of root-enhancing activity. However, within the effective range of IBA
evaluated, 24.6 or 49.3 mM produced the greatest rooting percentage in 4 of 5 studies testing
IBA. NAA solutions with concentrations between 2.5 and 7.5 mM NAA generally resulted in
similar rooting success. Rooting responses to increased IBA and NAA were both nonlinear;
rooting decreased with both too little and too much auxin. Combinations of IBA and NAA in the
same solution did not increase rooting percentage above what was achieved with one auxin. For
root system quality, auxin treated cuttings in one study, had significantly better root systems than
control, but there was no difference in the other study in which root quality was estimated.
125. Crook, R.W. and W.E. Friedman. 1992. Effects of pollen tube number and archegonium number
on reproduction in Douglas-fir: significance for seed orchard management. Canadian-Journal-of-
Forest-Research 22(10): 1483-1488.
Keywords: genetic tree improvement
seed orchard management
reproduction
tree/stand health
Abstract: Analyses of the relations between pollen tube number or archegonium number
and the number of fertilization events per ovule (fertilization number) in Douglas fir
(Pseudotsuga menziesii) growing at a seed orchard near Centralia, Washington, indicated strong
trends toward higher levels of simple polyembryony as both pollen tube number and archegonial
number increased on a per seed basis. These relations have a significant bearing on the
management of conifer seed orchards. Simple polyembryony has been proposed to be an effective
means of increasing competition on a per seed basis in conifers and, potentially, the overall
fitness of progeny. In conifers, supplemental mass pollination has the direct effect of increasing
the number of pollen tubes per ovule. Clonal variation in average number of archegonia per ovule
is also likely to exist among conifers. It is proposed that when used together, supplemental mass
pollination and selection of clones with high archegonial averages may enhance the fitness of
seed orchard progeny.
126. Crouch, G.L. and M.A. Radwan. 1981. Effects of nitrogen and phosphorus fertilizers on deer
browsing and growth of young Douglas-fir. Pacific-Northwest-Forest-and-Range-Experiment-
Station,-USDA-Forest-Service. Research-Note PNW-RN-368. 15 p.
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