Propagation container type, time in container, and root pruning affect root development of young Acer rubrum

Journal of Environmental Horticulture 30 (3): 150-160

Numerous propagation containers have been developed in an effort to reduce root deformities on tree and shrub nursery stock. Root attributes in containers are also impacted by retention time in the container. A popular shade tree, Acer rubrum L., was grown in 6 different propagation containers for two time periods and root pruned or not before shifting to 10 liter (3 gal) black plastic containers to evaluate root system quality. Root pruning when shifting into larger 10 liter (3 gal) containers resulted in more structural roots, adventitious roots from cuts, and woody second-order roots, growing closer to the substrate surface due to a reduced angle of departure from the trunk. Root pruning improved root system quality by increasing the number of straight, radially-oriented roots growing from all propagation containers except for Ellepots placed in contact with other Ellepots which had an equivalent high number of straight roots without pruning. By many measures, all propagation container types produced nearly equivalent root systems provided root balls were mechanically pruned by shaving off roots on the periphery when shifting to 10 liter (3 gal) containers. However, root pruning when shifting had no effect on mortality or trunk diameter growth in 10 liter (3 gal) containers. Without root pruning, the propagation container type and retention time had a large influence on root morphology in 10 liter (3 gal) containers.