Table 1.
Description of 38 root traits obtained in a phenotyping experiment.
| Traits | Description | Unit | Mean | Median | CV | Correlated trait No. | PC |
|---|---|---|---|---|---|---|---|
| BD | Branch density (branch number/ taproot length) | m−1 taproot | 120 | 120.9 | 0.39 | 31 | 3 |
| BD_sub | Subsoil branch density | m−1 | 79.4 | 71.7 | 0.50 | 31 | 3 |
| BD_top | Topsoil branch density | m−1 | 218.9 | 208.3 | 0.35 | 32 | 9 |
| BI | Branch intensity (branch number/root length) | m−1 root | 22.1 | 20.8 | 0.34 | 34 | 7 |
| BL | Branch length | cm | 343 | 298.7 | 0.62 | 26 | 1 |
| BL/TRL | Branch length/taproot length | 4.83 | 4.31 | 0.53 | 32 | 1 | |
| BL_ind | Average individual branch length | cm | 4.16 | 3.77 | 0.44 | 28 | 2 |
| BL_sub | Subsoil branch length | cm | 129 | 100.7 | 0.81 | 20 | 1 |
| BL_top | Topsoil branch length | cm | 214 | 181.8 | 0.62 | 32 | 1 |
| BLR | Branch length topsoil/subsoil ratio | 2.25 | 1.72 | 0.78 | 14 | 7 | |
| BN | Branch number | root−1 | 84.8 | 78 | 0.47 | 23 | 1 |
| BN_2nd | Second-order branch number | root−1 | 14.7 | 106 | 1.20 | 23 | 5 |
| BN_sub | Subsoil branch number | 40.8 | 34.8 | 0.70 | 24 | 1 | |
| BN_top | Topsoil branch number | 43.8 | 41.7 | 0.35 | 23 | 9 | |
| BNR | Branch number topsoil/subsoil ratio | 1.41 | 1.17 | 0.65 | 32 | 9 | |
| DCL_med | Root length in diameter class 0.75−1.25 mm | cm | 156 | 134.3 | 0.51 | 33 | 1 |
| DCL_thick | Root length in diameter class ≥1.25 mm | cm | 102 | 89.5 | 0.72 | 32 | 1 |
| DCL_thin | Root length in diameter class <0.75mm | cm | 218 | 186.2 | 0.64 | 32 | 6 |
| LBL | Length of the longest branch | cm | 21.7 | 8 | 0.90 | 29 | 5 |
| RA | Root surface area | cm2 | 128 | 112.3 | 0.59 | 31 | 1 |
| RD | Average root diameter | mm | 0.97 | 0.98 | 0.16 | 29 | 6 |
| RGR_2−4wk | Root growth rate (2–4 weeks) | cm d−1 | 1.89 | 1.88 | 0.26 | 24 | 8 |
| RGR_2wk | Root growth rate (0- 2 weeks) | cm d−1 | 1.92 | 1.86 | 0.50 | 23 | 4 |
| RGR_4−6wk | Root growth rate (4–6 weeks) | cm d−1 | 1.61 | 1.51 | 0.24 | 21 | 6 |
| RGR_4wk | Root growth rate (0–4 weeks) | cm d−1 | 1.72 | 1.77 | 0.23 | 30 | 2 |
| RGR_6wk | Root growth rate (0–6 weeks) | cm d−1 | 1.32 | 1.29 | 0.44 | 28 | 3 |
| RL | Root length | cm | 416 | 376 | 0.53 | 17 | 1 |
| RL_sub | Subsoil root length | cm | 180 | 155 | 0.63 | 33 | 1 |
| RL_top | Topsoil root length | cm | 234 | 202 | 0.57 | 19 | 1 |
| RLR | Root length ratio topsoil/subsoil | cm cm−1 | 1.55 | 1.27 | 0.70 | 25 | 7 |
| RM | Root dry mass | mg | 249 | 219 | 0.61 | 32 | 1 |
| RMR | Root-to-shoot mass ratio | 0.65 | 0.63 | 0.24 | 18 | 8 | |
| RTD | Root tissue density (mass/volume) | mg cm−3 | 76.9 | 70.6 | 0.45 | 27 | 9 |
| RV | Root volume | cm3 | 3.27 | 2.83 | 0.69 | 33 | 1 |
| SRL | Specific root length (length/mass) | cm mg−1 | 23.2 | 20.8 | 0.35 | 34 | 7 |
| TRL_2wk | Taproot length after 2 weeks | cm | 45.1 | 42.3 | 0.24 | 24 | 8 |
| TRL_4wk | Taproot length after 4 weeks | cm | 70.9 | 69.7 | 0.23 | 12 | 2 |
| TRL_6wk | Taproot length | cm | 26.6 | 26.3 | 0.27 | 22 | 3 |
Mean, median, and CV values for each trait are given. CV values >0.5 are in bold. Number of significantly correlated traits at P < 0.05 is given for each trait according to Pearson correlation coefficient analysis. Branch length and number refer to first-order branches unless specified. Topsoil = 0−20cm depth; subsoil = 20−120cm depth.