TABLE 4.
Fitted (Eq. 7) and measured (Obs.) values of parameters defining the light response curve of intrinsic water-use efficiency for C3 (soybean) and C4 species (grain amaranth).
| Species | α1 | WUEi–max (μmol mol–1) | Ii–sat (μmol m–2 s–1) | β1 (m2 s μmol–1) | γ1 (m2 s μmol–1) | Ki (μmol mol–1) | ||||||
| Eq. 7 | Obs. | Eq. 7 | Obs. | Eq. 7 | Obs. | Eq. 7 | Obs. | Eq. 7 | Obs. | Eq. 7 | Obs. | |
| Soybean | 1.53 ± 0.25a | – | 87.66 ± 3.38b | 89.24 ± 3.26b | 1153.95 ± 101.89a | 1250.00 ± 262.99a | (8.49 ± 0.62) × 10–5 | – | (7.52 ± 0.89) × 10–3 | – | 74.92 ± 6.16a | 75.35 ± 5.98a |
| Grain amaranth | 0.87 ± 0.19a | – | 131.32 ± 7.83a | 133.99 ± 7.63a | 1417.60 ± 90.68a | 1150.00 ± 125.83a | (1.21 ± 0.30) × 10–4 | – | (3.72 ± 1.26) × 10–3 | – | 40.35 ± 4.24b | 49.03 ± 5.69b |
The parameters are initial slope of the WUEi–I curve (α1), the maximum intrinsic water-use efficiency (WUEi–max) and the corresponding saturation irradiance (Ii–sat), and coefficients β1 and γ1 and Ki. All values are the means ± SE (n = 4). Different letters denote statistically significant differences (P ≤ 0.05) between soybean and grain amaranth within each column of fitted (Eq. 7) or measured (Obs.) values. There is no statistically significant difference between fitted (Eq. 7) and measured (Obs.) values for each parameter. See Table 1 for definitions of abbreviations.