Effects of Root Morphology on Nursery and First-Year Field Growth of Rooted Cuttings of Loblolly Pine

Abstract

Abstract Stem cuttings of loblolly pine (Pinus taeda L.) were rooted in a greenhouse and then scored for the number of roots per rooted cutting, the number of vertically oriented roots per rooted cutting, and symmetry of the arrangement of adventitious roots on the lower stem. Rooted cuttings were transplanted to a nursery bed, grown for 7 months, lifted and rescored, transplanted to a field location, and then measured after 1 yr in the field. Shoot height after the rooting period was correlated weakly with the number of roots per rooted cutting, but not with the number of vertical roots or root system symmetry. Nursery culture slightly reduced the number of roots per cutting and root system symmetry. Root orientation changed dramatically as roots elongated, with 94% of all roots scored as vertical after nursery growth. Shoot height after the period of nursery growth was still correlated weakly with root number, but not with the number of vertical roots. Rooted cuttings with symmetrical root systems were slightly taller than cuttings with asymmetrical root systems after growth in the nursery. After 1 yr in the field, shoot height was no longer correlated with root number. On average, cuttings with symmetrical root systems were only 2 mm taller than cuttings with asymmetrical root systems. These early growth data suggest it is not beneficial to impose culling criteria for cuttings rooted in a greenhouse and transplanted to a nursery based on the root system architecture at the time of rooting. However, growth and stability of rooted cuttings over a longer time period must be assessed. South. J. Appl. For. 22(4): 231-234.