Long-Term Container Effects on Root System Architecture of Longleaf Pine
Longleaf pine (Pinus palustris Mill.) seedlings cultured in three container cavity volumes and two cavity types (regular or copper oxychloride coating for root pruning) were excavated three years after planting in 2007 in Louisiana, U.S.A. Copper root pruning did not affect seedling growth. Seedlings from small cavities (60 ml) were smaller than those from medium (93 ml) or large (170 ml) cavities. About 59%, 35%, and 6% of the first-order lateral roots (FOLR) originated from the top, middle, and bottom thirds of the root plug in all treatments. Copper seedlings had more FOLR egress from the top root zone than regular seedlings which had almost even distribution of FOLR egress in all root zones. Copper treatment, however, did not completely ameliorate lateral root or taproot deformity. A few saplings toppled after Hurricane Gustav in 2008 and more saplings toppled in August 2009. Possible causes of sapling toppling are discussed.