Evaluation of sowing methods to determine the role of hypocotyl lift in longleaf pine seedling development
Sonderegger pine (Pinus x sondereggeri H.H. Chapm.) is a hybrid pine species of loblolly pine (Pinus taeda L.) and longleaf pine (Pinus palustris Mill.) that is culled when noticed during seedling processing and packing in the nursery. Early indication of the hybrid has been theorized as the absence of a seed wing stub or hypocotyl lift off of the growing medium surface, although neither of these theories has been proven. Two trials were conducted to determine the role of container cell color, growing medium depth in the cells, and the presence of a seed wing stub on longleaf pine hypocotyl lift. Seedlings grown in black container cells had increased hypocotyl lift and tendency for reductions in root-collar diameter growth regardless of seed wing stub presence. Genetic testing indicated that both wingless and winged seeds were true longleaf pine. This paper was presented at the Joint Annual Meeting of the Southern Forest Nursery Association and the Northeast Forest and Conservation Nursery Association (Pensacola, FL, July 17–19, 2018).