First year field growth of chemically root pruned containerized seedlings

Containers deform seedling root systems and have a potential to inhibit tree growth after outplanting. Ponderosa pine (Pinus ponderosa Dougl. ex Laws. var. ponderosa), western white pine (Pinus monticola Dougl. ex D. Don), and Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) were grown in containers coated with latex paint containing different concentrations of cupric carbonate and outplanted in a forest. Treatment effects on seedling growth and root morphology were determined after one growing season in the field. Seedling height was unrelated to treatment and stem diameter was not significantly affected (p0.05). New root growth in the upper portion of the root plug was significantly increased (p0.05). The optimal concentration of cupric carbonate for seedling root growth in the upper portion of the root plug was estimated by multiple regression.