Growth and Root Characteristics of Trees in Three Northern Nursery Production Systems

Three tree species (Betula nigra, Quercus bicolor, and Malus  ‘Prairie Fire’) were grown for two seasons from bare root stock in field, below-ground fabric container (FC), and pot-in-pot (PiP) production systems in USDA hardiness zone 5b. Increase in height and trunk caliper were nsd between production systems except for Betula nigra, where FC and PiP trees were smaller than field-grown trees. Root defects (circling, descending, bent roots) were minimal in field trees and most severe in PiP trees. Clean roots were separated into fine, small, medium and large size classes by diameter and dried at 38-48 C. Total root biomass was nsd between production methods for Malus and Quercus. Root mass was significantly greater and the root:shoot ratio was greater in PiP than field or FC for Betula. Multivariate logisitic regressions were used to compare root class proportions. PiP trees of all three species of had significantly greater proportions of small roots and less medium and large roots than the other treatments. Differences between FC and field grown trees were nsd for Quercus. Betula had a greater proportion of root mass in small to medium roots in FC compared to field, but FC Malus had a greater proportion of root mass in large roots compared to field.