TABLE 2.
Fitted (Eq. 1) and measured (Obs.) values of parameters defining the light response curve of photosynthesis for C3 (soybean) and C4 species (grain amaranth).
| Species | α | Anmax (μmol m–2 s–1) | Isat (μmol m–2 s–1) | β (m2 s μmol–1) | γ (m2 s μmol–1) | Rd (μmol m–2 s–1) | ||||||
| Eq. 1 | Obs. | Eq. 1 | Obs. | Eq. 1 | Obs. | Eq. 1 | Obs. | Eq. 1 | Obs. | Eq. 1 | Obs. | |
| Soybean | 0.059 ± 0.005a | – | 21.25 ± 0.53b | 21.79 ± 0.58 | 1925.38 ± 60.30a | 1800.00 ± 81.65 | (1.20 ± 0.10) × 10–4 | – | (1.25 ± 0.16) × 10–3 | – | 4.36 ± 0.46a | 4.90 ± 0.29a |
| Grain amaranth | 0.069 ± 0.001a | – | 63.36 ± 2.46a | – | 2186.67 ± 101.21a | – | (2.07 ± 0.15) × 10–4 | – | (1.08 ± 0.29) × 10–4 | – | 4.18 ± 0.35a | 4.99 ± 0.30a |
The parameters are initial slope of the An–I curve (α), the maximum net photosynthetic rate (Anmax) and the corresponding saturation irradiance (Isat), photoinhibition coefficient (β), saturation coefficient (γ), and dark respiration rate (Rd). 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. 1) or measured (Obs.) values. There is no statistically significant difference between fitted (Eq. 1) and measured (Obs.) values for each parameter. See Table 1 for definitions of abbreviations.