Table 4.

Effect of landscape planting depth on magnolia growth and anchorage.

Landscape planting depthzTree height increase 2012y (m)Root system radius eight months after plantingx (cm)Root:shoot eight months after plantingwDepth to root collarv (mm)
5 cm high2.5 br76 a0.71 a22 b
10 cm deep2.7 a59 b0.56 b156 a
Landscape planting depthPercent trunk with tangent/circling roots (>10 mm diameter) within 170 LuTotal CSA roots growing up >20 degree angle outside 170 L container root ball (mm2)Hinge point at five degrees trunk pullt (cm)Rest angle after winchings (degrees)
5 cm high66 a380 b18 a1.1 a
10 cm deep43 b972 a12 b0.8 b
  • z Root collar installed 5 cm above or 10 cm below landscape soil surface.

  • y Not significant (P > 0.10) for the years 2009–2011; trees installed September 2008.

  • x Distance between the edge of the planted 170 L root ball and the tip of the farthest root measured on the east and west side of tree.

  • w Ratio of distance between trunk and root tips to trunk and branch tips to the east and west.

  • v Distance between top of mulch and root collar.

  • u Percent of trunk circumference with roots growing tangent to or circling trunk that touched or were embedded into the bark.

  • t Distance between trunk and the point where root plate dipped to its lowest point at five degrees tilt.

  • s Trunk angle relative to vertical start position after winch is released following five degree trunk tilt 68 months after planting.

  • r Numbers followed by a different letter within columns are statistically different at P < 0.05; n = 24, averaged across planting depth in nursery container and root pruning due to insignificant interactions (P > 0.19 and 0.16, respectively) with depth in the landscape.