Longleaf pine bud development: influence of seedling nutritionThis article is part of a larger document. View the larger document here.
A subset of seedlings from a larger study (Jackson and others 2006, 2007) were selected and evaluated for two growing seasons to relate bud development, and root-collar diameter (RCD), and height growth with three nursery fertilization rates. We chose seedlings in the 0.5 (lowest), 2.0 (mid-range), and 4.0 (highest) mg of nitrogen per seedling treatments. Buds moved through three developmental phases and we confirmed that when RCD reached 25 mm (1 inch), seedlings were usually = 10 cm (4 inches), had elongated buds, and were exiting the grass stage. After two growing seasons, heights greater than 10 cm (4 inches) were reached on 20, 60, and 65 percent of the 0.5, 2.0, and 4.0-N seedlings, respectively. On average, higher N rates yielded seedlings with larger RCDs, taller heights, and more seedlings exiting the grass stage. On an individual seedling basis, however, we detected a reduction in RCD increment growth with increasing RCD at outplanting across all fertilizer treatments. This phenomenon may be related to root binding, but we have insufficient data to confirm the nature of this response. Further studies are needed to resolve this issue.