(WESTERN FOREST GENETICS ASSOCIATION ANNUAL MEETING, Moscow, Idaho,
August 3,
1967)
G ENETIC JUNK
A study to ascertain which flornl stages resulted in most effective pollina­
tion was made on 3 trees ne.ar Corvallis, Oregon.
si-lelling,
Conelets were pollinated at
burst, opening, spre3ding, closing, appressed and horizontal stages.
Surprisingly, equally high seed set was obtained over about a
opening, spreading, and closing floral stages.
10-day period at
Fairly good seed set was also ob•
tained for an additional period of 6 days at burst and appressed stages.
Pol­
lination was rare but possible from swelling to horizontal stages, a period of
about 20 days.
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This long range of time over which a conelet could possibly be pollinated
provides many opportunities for geneticists to improve pollination techniques .
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The same information has unexpected ramifications on the subject of the extent of
a seed zone.
In the 4 to 6 weeks period when pollination may be taking place in
a local stand, the zone of maximum· pollen release moves uphill 2,000 to 3,000
feet.
Several reasonable assumptions suggest that most seedlings of a local seed
source still would have resulted from local pollen.
However, in a normal dis­
tribution seedlings in decreasing numbers would probably result from pollen
originating up to 1,500 feet above or below the local stand.
Such seedlings would
probably be better suited to sites at higher or lower elevations,
form of "genetic junk" to be eliminated by the plant breeder.
species like Douglas-fir,
hence, are a
For a pioneering
where a 4,000-foot-long slope might sometimes be
seeded by very few surviving parents following fire, this same "genetic junk"
would be a very advantageous trait.
Roy R.
Silen,
Forestry Sciences Laboratory
3200 Jefferson Way, Corvallis,
Oregon
97331
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