From: Early root development of field-grown poplar: effects of planting material and genotype
 | Root mass (g) | Root length (m) | ||||||||
---|---|---|---|---|---|---|---|---|---|---|
 | Root diameter (mm) | Root diameter (mm) | ||||||||
Factor | <2 | 2 < 5 | 5 < 10 | 10 < 20 | ≥20 | 1 < 2 | 2 < 5 | 5 < 10 | 10 < 20 | ≥20 |
Soil depth (m) | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â |
 0 < 0.5 | 11.1a (2.0) | 29.8a (6.4) | 96.1a (19.3) | 114.1 (32.6) | 120.4 (67.3) | 7.3a (1.6) | 10.3a (1.8) | 6.7a (1.4) | 2.6 (0.6) | 2.2a (0.4) |
 ≥0.5 | 2.0b (0.4) | 10.1b (2.4) | 28.4b (6.4) | 66.2 (25.4) | 11.8 (9.1) | 1.2b (0.3) | 2.6b (0.5) | 1.7b (0.4) | 1.0 (0.3) | 1.1b (0.2) |
  P value | <0.001 | 0.004 | <0.001 | 0.556 | 0.087 | <0.001 | <0.001 | <0.001 | 0.102 | 0.040 |
Width (m) | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â |
 0 < 0.5 | 10.7a (2.4) | 27.0 (7.1) | 77.3 (19.1) | 199.5 (74.7) | 93.2 (54.7) | 5.8a (1.6) | 8.8 (1.9) | 4.2 (1.1) | 3.3 (0.9) | 2.6 (0.6) |
 0.5 < 1.0 | 3.5b (0.8) | 13.9 (3.9) | 37.2 (9.7) | 45.9 (18.1) | 27.4 (21.5) | 2.4b (0.7) | 4.2 (1.0) | 3.4 (0.9) | 1.2 (0.4) | 1.4 (0.4) |
 ≥1.0 | 3.7b (0.9) | 17.9 (5.3) | 70.0 (19.3) | 88.7 (40.0) | 103.9 (180.1) | 2.6b (0.8) | 5.2 (1.3) | 4.0 (1.1) | 2.1 (0.7) | 1.1 (0.3) |
  P value | 0.002 | 0.190 | 0.184 | 0.084 | 0.689 | 0.047 | 0.054 | 0.794 | 0.141 | 0.067 |
Depth × width |  |  |  |  |  |  |  |  |  |  |
  P value | 0.029 | 0.049 | 0.010 | 0.250 | 0.261 | 0.072 | 0.145 | 0.044 | 0.187 | 0.067 |