Evaluation of Longleaf Pine (Pinus palustris) Seedlots for the Prevalence of Hybridization
Sonderegger pine (Pinus x sondereggeri) occurs naturally where longleaf pine (Pinus palustris) and loblolly pine (Pinus taeda) are in close proximity and have the potential to cross-pollinate and hybridize. Seeds harvested from longleaf pine and processed to be used in nursery culture often have many hybrid seeds in the seedlot. Sonderegger pine seedlings can be detected in the nursery after germination by the presence of an elongated stem (like loblolly pine) along with a rosette of needles (like longleaf pine). If Sonderegger pine seedlings are overlooked, not culled in the nursery, and planted in the field, the hybrid pine may exhibit odd angled and shaped limbs, unpredictable growth rates, and poor wood quality.
Presently, there is no way to detect which seeds will be pure longleaf pine and which ones will have the hybridized characteristics of Sonderegger pine before they are sown in the nursery. A theory being proposed is that seeds missing the typical wing structure normally found on longleaf pine seeds may exhibit Sonderegger characteristics after germination compared to longleaf pine seeds with the intact wing structure. The wingless seeds that are typically found mixed in longleaf pine seedlots look similar to loblolly pine seed, thus, the theory of possible hybridization. The objective of this research is to compare longleaf pine seeds with and without a wing structure from seedlots collected across the southeastern United States and evaluate seedling development and genetic components for Sonderegger pine characteristics.
Information gathered from this research will hopefully identify: 1) if wingless longleaf pine seeds grow into being true Sonderegger pines or at least harbor loblolly pine characteristics and 2) a method to cull longleaf/loblolly pine hybrids at the seed level before being sown in the forest tree seedling nursery.
Principal Investigator: Jackson, Paul -- Agricultural Sciences
USDA Forest Service
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