Abstract
Forestry nursery container selection is a crucial decision when growing seedlings. Container choice will affect fine root development, increasing water and nutrient access. Paper pots are paper-wrapped plugs that utilize air pruning to change the root architecture of young trees and increase desired establishment characteristics. Comparing the development, egress, and root growth potential of a paper pot in an air pruning tray to an industry-standard solid wall container will give insights into the effect of air pruning on root architecture. Four container stocktypes of ponderosa pine were grown in 12 replication blocks over 30 weeks. Measurements for height, diameter, specific root length/area, egress by root zone, new growth from the lateral root’s origin point along the taproot, and mass were taken over the first growing season. Cell volume appeared to be the primary driver of response differences for paper pots in air pruning trays and not air pruning. The diameter and the ratio of a seedling’s height to diameter significantly increased over the solid wall container for two paper pots (p < .01). Root egress showed no significant interaction between the container and the egress zone of the root plug. The smallest paper pot container significantly increased root growth potential over all other containers in its middle and lower root plug zones (p < .001). However, it was most likely not influenced by air pruning and was influenced by drought stress conditioning from excessive plug dry down. Air pruning did not affect the paper pots because the paper wrapping remained moist for the paper cells throughout the experiment. A new irrigation regime and tray type are needed to maximize airflow and root pruning for paper pots in air pruning trays.