Table 2.
CO2/H2O gas exchange and chlorophyll fluorescence parameters (Anet, Vc, SC, Ci/Ca ratio, WUE, RL, RD, ETR, ETR/Agross and Y(NPQ)) of Medicago ciliaris leaves at a saturating light intensity after 3 weeks of drought treatment. Values represent mean ± SE (n = 5) and different letters indicate significant differences between treatments. Net CO2 assimilation rate (Anet) [μmol(CO2) m–2 s–1], photosynthetic efficiency (Vc), stomatal conductance (Sc) [mol(H2O) m–2 s–1], ratio of intercellular and atmospheric CO2 concentration (Ci/Ca ratio) [μmol(CO2) m–2 s–1], ratio of net CO2 assimilation rate and transpiration (A/E) (µmol/mmol), Photorespiration (RL) (µmol(CO2)*m−2*s−1), dark respiration (RD) (µmol CO2 m−2 s−1), electron transport rate (ETR) (µmol electrons m−2 s−1), gross CO2 assimilation (Agross) [μmol(CO2) m–2 s–1], quantum yield of regulated non-photochemical energy loss in PS II (Y(NPQ)), electron (e−).
| Treatment Parameter |
WPh (at 1500 μE m−2 s−1 PPFD) |
WPl (at 750 μE m−2 s−1 PPFD) |
||
|---|---|---|---|---|
| 0% Bc | 2% Bc | 0% Bc | 2% Bc | |
| Anet (µmol CO2 m−2 s−1) | 10.667 a ± 0.566 |
8.029 b ± 0.803 |
2.513 d ± 0.294 |
4.495 c ± 0.801 |
| Vc (µmol CO2*m−2*s−1) | 0.057 a ± 0.008 |
0.048 ac ± 0.012 |
0.030 b ± 0.001 |
0.045 bc ± 0.012 |
| SC (µmol CO2 m−2 s−1) | 0.07 a ± 0.008 |
0.05 b ± 0.004 |
0,021 c ± 0,008 |
0.03 c ± 0.007 |
| Ci/Ca ratio | 0.367 a ± 0.05 |
0.323 a ± 0.06 |
0.510 b ± 0.09 |
0.422 b ± 0.01 |
| WUE (A/E) | 9.476 b ± 1 27 |
6.595 c ± 0.21 |
6.4 d ± 1.85 |
11.04 a ± 0.61 |
| RL (µmol(CO2)*m−2*s−1) | 11.88 b ± 0.73 |
13.59 a ± 0.95 |
9.05 c ± 0.56 |
8.01 c ± 0.72 |
| RD (µmol CO2 m−2 s−1) | 1.189 ab ± 0.141 |
0.640 b ± 0.157 |
1.675 a ± 0.600 |
0.900 b ± 0.452 |
| ETR (µmol e− m−2 s−1) | 182.23 b ± 7.71 |
195.73 a ±8.15 |
112.38 c ± 3.9 |
109.6 c ± 6.42 |
| ETR/Agross ratio (e−/CO2) | 7.75 a ± 0.2 |
8.65 a ± 0.26 |
8.43 a ± 0.63 |
8.4 a ± 0.68 |
| Y(NPQ) | 0.382 a ± 0.04 |
0.301 b ± 0.06 |
0.329 a ± 0.03 |
0.371 a ± 0.029 |