Table 7. Predication models (the range for original and validation data of agronomic parameters (Par.), R², slope, intercept and RMSE) using partial least square regression (PLSR) for the full wavelength range (350–2500 nm).
Models are based on the calibration data of two years for green leaf area (GLA), aboveground total dry weight (TDW), grain yield (GY) and water use efficiency (WUE) under individual irrigation rates and plant densities.
| Irrigation rates | Plant densities (D) | |||||||
|---|---|---|---|---|---|---|---|---|
| Statistics | 1.00 ET | 0.75 ET | 0.50 ET | D1 | D2 | D3 | D4 | D5 |
| GLA (cm2 plant-1) | ||||||||
| Range of orginal data | 315.3–510.4 | 252.5–377.0 | 138.9–244.6 | 178.2–407.9 | 221.7–461.8 | 197.0–486.8 | 152.7–510.4 | 138.9–432.8 |
| Range of validation | 287.2–461.8 | 243.1–367.3 | 90.0–393.2 | 209.1–368.5 | 249.8–433.2 | 274.0–461.8 | 175.3–410.9 | 90.0–393.2 |
| R2 | 0.89*** | 0.46* | 0.82*** | 0.87*** | 0.79** | 0.83*** | 0.84*** | 0.75** |
| Slope | 0.95 | 1.05 | 3.3 | 0.68 | 0.90 | 0.53 | 0.64 | 0.93 |
| Intercept | 21.6 | -51.50 | -364.6 | 96.0 | 21.7 | 171.0 | 97.6 | - 0.25 |
| RMSE | 48.1 | 33.2 | 78.1 | 34.6 | 39.6 | 61.3 | 55.5 | 60.8 |
| TDW (g m-2) | ||||||||
| Range of orginal data | 950.3–2343.3 | 939.6–1683.4 | 545.9–1019.4 | 568.2–1047.2 | 978.3–1640.9 | 886.2–2186.0 | 626.9–2343.3 | 545.9–1823.6 |
| Range of validation | 997.1–1992.7 | 852.8–1509.8 | 450.4–1453.3 | 606.2–1497.4 | 934.5–1837.6 | 1093.7–1992.7 | 798.4–1749.0 | 450.4–1640.9 |
| R2 | 0.59* | 0.27 | 0.74** | 0.66* | 0.70** | 0.74** | 0.91*** | 0.88*** |
| Slope | 0.50 | 0.44 | 1.69 | 1.46 | 1.09 | 0.54 | 0.52 | 0.87 |
| Intercept | 750.8 | 616.8 | -322.8 | -186.6 | 45.2 | 654.4 | 531.4 | 61.4 |
| RMSE | 350.6 | 295.4 | 296.4 | 290.9 | 338.6 | 331.1 | 367.3 | 228.6 |
| GY (g m-2) | ||||||||
| Range of orginal data | 506.3–959.8 | 479.1–820.4 | 329.8–501.9 | 360.7–568.5 | 501.6–854.4 | 443.9–952.8 | 404.0–959.8 | 329.8–884.3 |
| Range of validation | 604.7–913.8 | 493.2–756.5 | 319.8–573.4 | 319.8–684.5 | 505.3–913.8 | 477.6–863.1 | 523.3–872.1 | 343.4–742.2 |
| R2 | 0.60** | 0.56* | 0.68** | 0.74** | 0.83** | 0.98*** | 0.80** | 0.84** |
| Slope | 0.53 | 0.63 | 2.08 | 1.42 | 0.92 | 0.77 | 0.60 | 0.70 |
| Intercept | 358.4 | 200.7 | -357.9 | -134.8 | 106.2 | 136.6 | 253.9 | 128.0 |
| RMSE | 114.69 | 103.46 | 128.97 | 100.22 | 80.64 | 141.0 | 114.64 | 109.21 |
| WUE (g m-2 mm-1) | ||||||||
| Range of orginal data | 0.86–1.60 | 1.05–1.79 | 1.01–1.53 | 0.86–1.16 | 1.31–1.63 | 1.35–1.79 | 1.23–1.61 | 1.01–1.48 |
| Range of validation | 0.96–1.55 | 1.06–1.65 | 1.02–1.53 | 0.96–1.41 | 1.30–1.58 | 1.20–1.65 | 1.33–1.63 | 1.02–1.46 |
| R2 | 0.66** | 0.83*** | 0.55* | 0.74** | 0.16 | 0.73** | 0.88*** | 0.96*** |
| Slope | 0.74 | 0.71 | 0.68 | 2.27 | 0.45 | 0.80 | 0.61 | 0.87 |
| Intercept | 0.33 | 0.40 | 0.40 | -1.28 | 0.76 | 0.21 | 0.60 | 0.15 |
| RMSE | 0.205 | 0.105 | 0.113 | 0.234 | 0.154 | 0.144 | 0.09 | 0.049 |
*, **, *** indicate significance at 0.05, 0.01 and 0.001 P level, respectively. D1, D2, D3, D4, and D5 indicate plant density of 150, 250, 350, 450, and 550 seeds m-2, respectively.