of
1st pollination x3
[Symbol: female] parent [Symbol: female] parent
4-4 7-4 4-4 7-4
(JxA) (JxJA) (JxA) (JxJA)
----------------------------------------------------------------------------------------
Normal emasculation 39 17 29.1 13.7
Only unisexual catkins removed 23 19 14.5 0.0
Not emasculated, but pollinated 28 18 25.0 3.7
Not emasculated, }
not pollinated } Control 28 25 1.2 0.0
Not bagged, branches tagged,
open pollinated 26 23 44.9 17.4
----------------------------------------------------------------------------------------

Bagging apparently was partly injurious on these two trees and caused
some decrease in nut yield. There is, however, no evidence that
emasculation in itself causes a decreased nut yield, rather it appears
to be somewhat beneficial if we are to judge from the results of this
experiment. At least, one would be justified in concluding that any
harmful effect is negligible. Completely emasculated flowers yielded
29.1 and 13.7 per cent as compared to 14.5 and 0.0 per cent where only
unisexual male catkins were removed, and 25.0 and 3.7 per cent where no
emasculation was done. The controls which were not emasculated and not
hand pollinated, show that the trees are practically completely self
sterile; only an occasional nut is set from self-fertilization.

Vegetative Propagation

In vegetative propagation the tree breeder has a very important tool.
For instance, if a number of desirable phenotypes have been selected in
the forest, they can be propagated vegetatively and planted under
uniform conditions where it will be possible to "estimate" their
genotype, without the time-consuming progeny testing. Trees propagated
vegetatively from old mature trees usually will start flowering very
soon after they become established; thus the necessity of doing
pollination work in very large trees can be eliminated. Furthermore, it
enables the tree breeders to maintain trees of a desirable genotype
unaltered for an indefinite length of time without first establishing
pure l