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Open-pollinated progeny trials of Fraser fir (Abiesfraseri (Pursh) Poir.) assessed at 8 years provided genetic parameter estimates for growth, Christmas tree quality traits, and wholesale value at harvest age. Significant variation was found between and within nine different seed sources. Estimated individual tree heritabilities of important traits ranged from a low of 0.13 for USDA Christmas tree grade to a moderate value of 0.33 for crown diameter. Heritabilities within the better performing seed sources tended to be higher. Of the two traits that determine wholesale value, USDA grade and height class, the latter proved to have the greater influence, both phenotypically and genetically. Genetic correlations of early age height growth with 8-year total height, height class, USDA Christmas tree grade, and individual tree wholesale value proved favorable and strong (range of 0.57–0.96). In combination with moderate heritabilities for early growth traits, such correlations provide potential for effective early age selections in Fraser fir Christmas trees.

Application . Grafting is widely used to propagate conifers . Selected rootstocks can be used to improve graft success, reduce incompatibility, alter scion vigor and increase seed production . It may also be possible to alter crown characters and scion physiology.Abstract . The literature on rootstock effects (on scions) in conifers was reviewed, specifically: graft success, compatibility, size, reproduction, phenology, crown and needle characters, mineral content, organic compounds, water relations, disease resistance and wood properties . Scions usually had higher graft success and less incompatibility on more closely related rootstocks although there were exceptions . Even intergeneric grafts have succeeded on occasion . Although there were marked rootstock effects on growth and reproduction, the effects did not follow a pattern with increasing relationship . It is also likely that some crown characters and the nutrient content of scions can be manipulated by the use of rootstocks. For many characters, a specific rootstock may give a desired result only for a limited number of scion types (species, cultivars or clones) . With some exceptions, the review shows that the subject has not been comprehensively studied . Many of the studies were either short-term, inadequately replicated, or poorly designed to allow firm conclusions about rootstock effects . The physiological and biochemical mechanisms, which cause the changes seen in morphology, are not well understood . Further research and more comprehensive study of rootstock effects on scion biology are recommended .

The stability of wood specific gravity for 12-year-old loblolly pine (Pinustaeda L.) was evaluated for 18 open-pollinated families and four bulked seed lots representing provenances from the eastern shore of Maryland; Marion County, Florida; Gulf Hammock, Florida; and Livingston Parish, Louisiana. Wood samples were collected from seven plantings chosen to provide a north–south and east–west sample distribution essentially encompassing an area spanning the natural range of loblolly pine. There was significant genotype × environment interaction, and 4 of the 18 families were classified as unstable for specific gravity. These four families accounted for 49.5% of the genotype × environment interaction sum of squares. However, the loss in potential gain in a breeding program for specific gravity due to the presence of a significant genotype × environment interaction was estimated to be only 1%. Loblolly pine from the Florida provenances and from the widely planted Livingston Parish provenance consistently displayed low specific gravity and ranked at or near the bottom at all test locations, including the southernmost plantings.

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