Seed Source ancl Gralt Compatibility in Douglas-Fir
Note by Donald L. Copes
Abstract.
m
No evidence of geographic variation
proportion of compatible grafts was found in
6- to 12-year-old trees grown from seed collected
m
10
Western
States
and
British
Columbia.
Forest Sc:i. 17:499.
Additional key words.
Pseudotsuga menziesii,
seed orchard.
CASH
INVESTMENT
in
clonal
Douglas-fir
(Pseudotsuga menziesii) seed orchards in the
Pacific Northwest is considerable. The job of
seed orchardists would be much easier if
testing for incompatibility could be reduced.
Discovery of a seed source of
rootstocks
which is highly compatible with west coast
Douglas-fir scions might accomplish this goal.
No past literature bears directly on this prob­
lem, but the existence of considerable geo­
graphic variation in other traits suggests that
geographic variation in graft compatibility
may also be large.
My experiment was started to determine
whether extensive seed source screenings to
tdentify compatible rootstocks would be
worthwhile. Specifically, average compatibil­
Ities of Rocky Mountain (RM) scions on
coastal (C) rootstocks, of C on RM, of C on
C, and of RM on RM were compared from
grafts made between 6- to 12-year-old trees
growing in a breeding arboretum near Cor­
vallis,
Oregon.
This arboretum had been
domly within the arboretum. To obtain a
random assortment of graft combinations, I
proceeded down the rows, grafting a seton
from Tree 1 on a lateral branch of Tree 2,
a scion from Tree 2 on a lateral branch of
Tree 3, etc. In this way, 457 grafts were made
in the springs of 1968 and 1969. Half were
Rocky Mountain on Rocky Mountain; the
remainder were divided almost equally be­
tween C on RM, RM on C, and C on C
combinations. The grafts were sacrificed 18
months later, and the graft-unions were exam­
ined microscopically according to the method
previously described by Copes (USDA Forest
Serv. Res. Note PNW-70, 8 p. 1967).
Of the 457 grafts, 74 percent were judged
to· be compatible. This proportion vaned
only slightly from 71 percent (C on RM)
to 76 percent (RM on RM) with the geo­
graphic combination between graft and
scion. Analyzed another way, the success
ratio was nearly the same whether graft and
scion were from the same State (76 percent
. percent suc­
success) or different States (73
cess). None of the above differences were
significant at the 0.05 level.
Apparently, selection of particular races or
varieties of Douglas-fir as understocks does
not offer a solution to the graft incompatibthty
problem in this species. For the present,
selecting highly compatible individual trees
within areas as potential seed sources of highly
compatible stocks is recommended.
established by Helge Irgens-Moller of Oregon
State University with seed collected from 57
The author is Plant Geneticist, Forestry Sci­
different stands in 11 Western States and
ences Laboratory, Pacific Northwest Forest and
provinces (British Columbia to Montana and
Range Exp. Sta., USDA Forest Service, Corvalhs,
south to California and New Mexico). Trees
Oregon 97330,
of different seed sources were located ran­
1971.
Manuscript received May 11,
volume 17, number 4, 1971 I 499