Root development of container-reared, nursery-grown, and naturally regenerated pine seedlings

Root systems of 6- to 10-year-old red pine (Pinusresinosa Ait.) and jack pine (Pinusbanksiana Lamb.) trees reared in various containers were excavated from four different sites and studied. Nursery-grown and naturally regenerated trees of similar age and stem size growing on the same sites were used for comparison. Root cross-sectional area (RCSA) taken 5 cm from the stem, a measurement found to be highly correlated (r = 0.94) with root weight (In-In transformation), was used to describe root system size. The average RCSA's of jack pine reared in paper pots, book planters, and nonribbed styroblock-2 containers were smaller than those of naturally regenerated seedlings, but the differences were not statistically significant. Jack pine and red pine reared in Ontario tubes had significantly larger RCSA's than nursery-grown trees. There were some differences in radial distribution of horizontal roots, and the apportionment between horizontal and vertical root components differed between some of the seedling types.