Genetic Efficiency in Loblolly Pine Seed Orchards

Using seven allozyme loci as genetic markers, gene frequencies in the bulked seed crop of two seed orchards were compared to those expected on the basis of maximum genetic efficiency. Significant deviations from expected values were found for allelic frequencies in embryos as well as in both the ovule and pollen pools which produced the embryos. While contamination from pollen sources in surrounding stands (estimated at 28%) may be important in causing deviations from expectation in the pollen pool, self-fertilization does not appear to be a problem since the proportion of selfed progeny was estimated to be very low (< l.5%) in these orchards. When seeds were separated by size there was a substantial loss of genetic variability in the ovule pool within a size class. Several other factors which might be responsible for decreased genetic efficiency are considered. Implications of these findings for seed orchard management are discussed. Additional keywords: Pinus taeda, allozyme variation, seed orchards, self-fertilization, pollen contamination

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Author(s): Sharon T. Friedman, W. Thomas Adams

Publication: Tree Improvement and Genetics - Southern Forest Tree Improvement Conference - 1981

Section: Section 4: Seed Utilization and Seed Orchard Management