Effect of root pruning when landscape planting (May 2010) on trunk diameter increase, visual root imprint from container, and CSA of the largest circling roots at 170 L container position in subsequent four years.
| Root pruningz | Trunk diameter increase 2012 growing seasony (mm) | Visual root imprint rating from 170 Lx container (1–5) at 170 L positionw (mm2) | CSA largest diameter root >5 mm diameter circling at 170 L positionw (mm2) | Total CSA three largest roots >5 mm diameter circling | |
|---|---|---|---|---|---|
| Acer | |||||
| Yes | 26 av | 1.3 b | 20 b | 26 b | |
| No | 26 a | 3.9 a | 830 a | 1605 a | |
| Magnolia | |||||
| Yes | 25 bv | 1.2 b | 26 b | 34 b | |
| No | 30 a | 4.0 a | 299 a | 579 a | |
↵z Roots and substrate on periphery 5 cm of 170 L root ball removed at landscape planting by shaving; Ulmus were not subjected to root pruning at planting.
↵y Magnolia and Acer trunk diameter increase during the first (2010), second (2011), and fourth (2013) growing seasons after planting not significant (P > 0.12).
↵x Imprint imposed on top 10 cm of root system by roots deflecting in a pattern conforming to the 170 L nursery container wall, evaluated June 2014; 1 = little imprint, 5 = highly visible imprint; P < 0.0001; imprint imposed by 11 L and 57 L containers not significantly affected by root pruning (P > 0.16).
w Cross-sectional area (CSA) of largest roots top 10 cm of soil evaluated June 2014; P < 0.0001.
↵v Means in a column with a different letter are statistically different at P < 0.03; n = 20, mean across retention time due to insignificant interaction (P > 0.14).