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  • Author or Editor: Steven E. McKeand x
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Abstract

In a field study comparing seedlings and tissue culture plantlets of loblolly pine (Pinus taeda L.) after two growing seasons, the plantlets had numerous growth and morphological characteristics of mature trees. The appearance of mature traits was surprising, since the plantlets originated from juvenile, embryonic tissues. Evidence from other studies with tissue culture propagation of pine species suggests that plantlets often express mature characteristics. Some of the characteristics of the loblolly pine plantlets, such as lower incidence of fusiform rust [Cronartium quercuum Berk. Miyabe ex Shirai f. sp. fusiforme (Cumm.) Burds. et Snow], fewer branches, and less taper, would be of great economic advantage if the growth rates remain similar to comparison seedlings.

Open Access

A series of open-pollinated progeny tests of Fraser fir [Abies fraseri (Pursh) Poir.] was analyzed to determine genetic variation of spring frost damage to the terminal leader and lateral branches after a late season frost in May of the third year in the field. The level of spring frost damage was also compared with bud flush dates that had been measured in the nursery before field planting. Seed sources differed significantly for lateral branch frost damage, and families within source differed significantly for both terminal leader and lateral branch frost damage. Greater terminal and lateral frost damage were significantly associated with greater height for all years. As expected, parent elevation was negatively associated with progeny height. Less lateral frost damage was also associated with later terminal and lateral bud flush dates in the nursery. In addition, higher parent elevation was associated with later lateral bud flush dates of progeny in the nursery. Terminal and lateral bud flush dates in the nursery showed high individual tree within-population heritability values of 0.85 and 0.73, respectively. Similar heritability values for the frost damage measurements were low, 0.045 for terminal leader damage and 0.14 for lateral branch damage. Many of the fast-growing families quickly made up for any loss of height from frost damage so that frost damage should not greatly affect the rotation length.

Free access

A series of open-pollinated progeny tests of Fraser fir [Abies fraseri (Pursh) Poir.] was analyzed to determine natural variation among six geographic seed sources and to estimate genetic parameters for traits important in Christmas tree production. Highly significant differences were found among seed sources and families within sources (P ≤ 0.0001) for height after 4 years in the field. The individual-tree within-population heritability values for the traits measured in Year 4 ranged from 0 to 0.44, with height having the highest heritability, overall tree quality having a heritability of 0.14, and bud and branching traits having varying heritabilities. Heritability values for height at age 4 varied greatly among the six sources, from 0.15 for the Black Mountains to 0.67 for the Great Smoky Mountains. Highly significant seed source × site interactions as well as family within source × site interactions existed for height. Stability variance analysis, after removing the environmental heterogeneity, showed significant instability across the test sites for two of the six seed sources for height after 4 years, and some rank changes occurred. The high heritability values for height indicate that economically important genetic gains can be made in Fraser fir for Christmas tree production because of the importance of height in determining Christmas tree value.

Free access