Expected Genetic Gains and Development Plans for Two Longleaf Pine

Selection and thinning plans were developed for two longleaf pine (Pinus palustris Mill.), third-generation seedling seed orchards located in southeastern Mississippi and central Louisiana. The two orchards were part of several long-term experimental field tests designed to investigate genetic variation in height growth and brown spot needle blight (caused by Scirrhia acicola (Dearn.) Siggers) resistance in a longleaf pine population. Phil Wakeley identified the original population in the 1920s in southeastern Louisiana and E. B. Snyder and H. J. Derr continued to advance the population through selection and breeding for early height growth and brown spot resistance. Our current results suggest that both traits can be improved by another round of selection and deployment through these third-generation seedling seed orchards. Operationally expected genetic gains range from 4.7% to 9.1% for height at age 9 years and 3.6% to 4.3% for brown spot resistance through age 4 years. These expected gains represent an approximate tripling in early height growth rate and doubling of brown spot resistance compared to the second generation.

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Author(s): C. Dana Nelson, Larry H. Lott, David P. Gwaze

Publication: Tree Improvement and Genetics - Southern Forest Tree Improvement Conference - 2005