12
The four figures on height superiority represent those families chosen as the top 20 percent on the basis of family performance in the progeny test. They estimate the expected growth of seedlings from an orchard of such parents.
This estimate is conservative for the J. E. Schroeder orchard of full-sib families, as any contribution from within-family selection would be added.
Percent volume superiority would be two to three times as high.
HALE VS. FEMALE CONTRIBUTIONS TO FULL-SIB FAMILIES-­
DO WE HAVE A SERIOUS CONCERN WITH ORCHARD CROSSES? by Roy Silen
The very large numbers of full-sib crosses in the J. E. Schroeder Seed Orchard has provided a sensitive direct answer to a serious concern. Isozyme studies have suggested that errors in crossing associated with contaminating pollen sources and with labeling, when done on a commercial scale, could have been unacceptably high. If so, the female parent's contribution to height of the full-sib family should provide a higher correlation coefficient than the male's contribution when average heights of wind-pollinated families over eight or more test sites are regressed against the family mean heights of the crosses in the orchard.
Two Cooperatives provide data for such a comparison, both comparing 6-year full-sib heights versus 10-year heights of each parent's progeny. One is the
Umpqua Cooperative based on 9B crosses which was studied with isozyme markers and which was indicated to have many instances of questionable male parentage. The other, Snow Peak Cooperative, is based on 126 crosses.
In neither case was there any substantial difference between male and female contribution as measured by correlation coefficients.
For Umpqua Cooperative n
=
9B
For Snow Peak Cooperative n
=
126 male r female r male r female r
=
=
=
=
0.345B
0.3504
0. 6906
0.6B22
Such close matching of male and female coefficients means that whatever problems appear in the crosses concerning inheritance of growth is equally shared b y both male and female contributions.
• r