Table 1. Model performance statistics for calibration (C) and cross-validation (CV) data generated via using 500 random permutations of the data, with 80% used for calibration and 20% used for cross validation for models predicting leaf traits from maize spectra.
Averaged R2, RMSE, and NRMSE. Data are shown as mean ± sd. Values in parentheses are fifth and 95th percentil confidence intervals.
| Trait | R2 | RMSE | Bias | NRMSE | ||||
|---|---|---|---|---|---|---|---|---|
| C | CV | C | CV | C | CV | C | CV | |
| A (µmol CO2 m−2 s−1) | 0.92 ± 0.01 (0.91–0.94) | 0.84 ± 0.05 (0.74–0.91) | 4.61 ± 0.23 (4.24–4.95) | 6.61 ± 0.93 (5.09–8.15) | 0.0 ± 0.0 (0.0 ± 0.0) | 0.28 ± 1.60 (−2.43–2.95) | 9 | 13 |
| E (mmol water m−2 s−1) | 0.92 ± 0.01 (0.91–0.93) | 0.83 ± 0.05 (0.74–0.90) | 0.77 ± 0.04 (0.71–0.82) | 1.15 ± 0.15 (0.91–1.40) | 0.0 ± 0.0 (0.0–0.0) | 0.02 ± 0.27 (−0.41–0.48) | 9 | 13 |
| gs (mol water m−2 s−1) | 0.86 ± 0.01 (0.84–0.89) | 0.73 ± 0.08 (0.59–0.83) | 0.05 ± 0.00 (0.05–0.06) | 0.08 ± 0.01 (0.06–0.10) | 0.0 ± 0.0 (0.0 ± 0.0) | 0.00 ± 0.02 (−0.03–0.03) | 9 | 15 |
| Ci (µmol mol−1) | 0.69 ± 0.03 (0.63–0.74) | 0.51 ± 0.17 (0.22–0.74) | 40.43 ± 1.88 (37.41–43.37) | 50.06 ± 7.52 (37.50–63.03) | 0.0 ± 0.0 (0.0 ± 0.0) | −0.36 ± 11.76 (−19.25–18.11) | 13 | 16 |
| WUEi (µmol CO2 mmol−1 water) | 0.85 ± 0.03 (0.80–0.88) | 0.69 ± 0.17 (0.36–0.88) | 0.53 ± 0.02 (0.50–0.56) | 0.69 ± 0.10 (0.55–0.86) | 0.0 ± 0.0 (0.0–0.0) | 0.02 ± 0.16 (−0.26–0.29) | 7 | 9 |
| WUEin (µmol CO2 mmol−1 water) | 0.64 ± 0.04 (0.57–0.70) | 0.44 ± 0.17 (0.17–0.71) | 21.35 ± 0.92 (19.66–22.62) | 26.57 ± 4.01 (20.41–33.38) | 0.0 ± 0.0 (0.0 ± 0.0) | 0.10 ± 6.11 (−10.59–9.06) | 12 | 14 |
| Tl (°C) | 0.95 ± 0.00 (0.94–0.96) | 0.89 ± 0.03 (0.82–0.93) | 0.52 ± 0.02 (0.48–0.55) | 0.79 ± 0.11 (0.61–0.96) | 0.0 ± 0.0 (0.0 ± 0.0) | 0.01 ± 0.18 (−0.31–0.27) | 5 | 10 |
| ChlSPAD | 0.75 ± 0.02 (0.73–0.78) | 0.61 ± 0.09 (0.45–0.75) | 1.72 ± 0.06 (1.61–1.81) | 2.22 ± 0.27 (1.74–2.63) | 0.0 ± 0.0 (0.0 ± 0.0) | 0.02 ± 0.53 (−0.91–0.80) | 10 | 13 |
| Ψw (−MPa) | 0.85 ± 0.01 (0.83–0.87) | 0.63 ± 0.10 (0.44–0.77) | 0.10 ± 0.00 (0.10–0.11) | 0.17 ± 0.02 (0.13–0.20) | 0.0 ± 0.0 (0.0 ± 0.0) | 0.01 ± 0.04 (−0.06–0.07) | 9 | 15 |
| Ψπ (−MPa) | 0.79 ± 0.02 (0.77–0.82) | 0.60 ± 0.11 (0.40–0.76) | 0.06 ± 0.00 (0.05–0.06) | 0.08 ± 0.01 (0.07–0.10) | 0.0 ± 0.0 (0.0 ± 0.0) | 0.00 ± 0.02 (−0.04–0.03) | 13 | 17 |
| Ψπ100 (−MPa) | 0.77 ± 0.02 (0.74–0.81) | 0.53 ± 0.14 (0.24–0.73) | 0.05 ± 0.00 (0.05–0.05) | 0.07 ± 0.01 (0.06–0.09) | 0.0 ± 0.0 (0.0 ± 0.0) | 0.00 ± 0.02 (−0.03–0.03) | 10 | 14 |
| RWC (%) | 0.93 ± 0.01 (0.92–0.94) | 0.90 ± 0.04 (0.80–0.94) | 3.22 ± 0.12 (3.04–3.43) | 3.83 ± 0.48 (2.92–4.62) | 0.0 ± 0.0 (0.0 ± 0.0) | 0.01 ± 0.93 (−1.51–1.56) | 7 | 9 |
| Suc (g g−1) | 0.97 ± 0.01 (0.96–0.97) | 0.86 ± 0.05 (0.77–0.92) | 0.15 ± 0.01 (0.13–0.17) | 0.32 ± 0.05 (0.25–0.40) | 0.0 ± 0.0 (0.0 ± 0.0) | −0.01 ± 0.09 (−0.16–0.11) | 5 | 10 |
| SLA (cm2 g−1) | 0.91 ± 0.01 (0.90–0.93) | 0.83 ± 0.06 (0.71–0.91) | 12.10 ± 0.49 (11.28–12.84) | 17.21 ± 2.50 (13.17–21.11) | 0.0 ± 0.0 (0.0 ± 0.0) | −0.24 ± 3.92 (−6.45–6.39) | 7 | 10 |
| TSD (mm−2) | 0.99 ± 0.00 (0.99–1.00) | 0.45 ± 0.16 (0.16–0.68) | 1.42 ± 0.19 (1.10–1.71) | 14.28 ± 2.16 (10.72–17.91) | 0.0 ± 0.0 (0.0 ± 0.0) | 0.27 ± 3.30 (−4.79–5.92) | 1 | 12 |