Table 1.
The water availability effect (control versus drought) in terms of leaf water content (LWC), leaf osmotic potential (Ψs), stomatal conductance (gs), transpiration (E), leaf temperature (Tleaf), leaf respiration (Rleaf), saturating maximum photosynthetic rate (Asat), maximum carboxylation velocity of Rubisco (Vcmax), and the maximum electron transport rate contributing to RuBP regeneration (Jmax), intercellular CO2 concentration (Ci), the maximal photochemical efficiency (Fv/Fm), relative quantum efficiency of PSII photochemistry (ΦPSII), efficiency of energy capture by open PSII reaction centres (), photochemical quenching (qP), non-photochemical quenching (NPQ), total chlorophyll (Chl a+b), electron transport through Photosystem II [Je(PSII)], electron transport through photosynthetic carbon reduction [Je(PCR)], electron transport through photorespiratory carbon oxidation [Je(PCO)], nodule respiration (Rnodule), and acetylene reduction assay (ARA) of Medicago sativa plants
Measurements were conducted at the end of the experiment, when plants were 3 months old. Each value represents the mean ±SE (n=8). The different letters indicate significant differences (P <0.05).
| Parameter | Control | Drought |
| Leaf | ||
| LWC | 76.31±0.97 a | 51.68±8.31 b |
| Ψs leaf (MPa) | –1.45±0.05 a | –3.85±0.61 b |
| gs (mmol H2O m−2 s−1) | 527.14±13.83 a | 98.14±15.81 b |
| E (mmol H2O m−2 s−1) | 0.65±0.12 a | 0.33±0.05 b |
| Tleaf (°C) | 24.04±0.31 b | 26.78±0.6 a |
| Rleaf (μmol m−2 s−1) | –2.30±0.29 a | –1.6±0.38 a |
| Asat (μmol m−2 s−1) | 25.83±3.03 a | 10.83±2.77 b |
| Vcmax(μmol m−2 s−1) | 139.15±11.7 a | 106.11±9.00 b |
| Jmax (μmol m−2 s−1) | 150.30±7.48 a | 126.84±5.12 b |
| Ci (μmol mol−1) | 297.83±27.47 a | 204.25±16.21 b |
| Fv/Fm | 0.76±0.01 a | 0.78±0.02 a |
| ΦPSII | 0.29±0.03 a | 0.20±0.02 b |
| 0.50±0.03 a | 0.41±0.03 b | |
| qP | 0.61±0.03 a | 0.44± 0.06 b |
| NPQ | 1.22±0.1 b | 2.03± 0.08 a |
| Chl a+b (mg g−1 DM) | 8.89±0.8 a | 9.87±90.05 a |
| Je(PSII) (μmol e−2 s−1) | 149.3±2.81 a | 117.45±4.54 b |
| Je(PCR) (μmol e−2 s−1) | 115.48±2.8 a | 74.00±3.31 b |
| Je(PCO) (μmol e−2 s−1) | 33.82±1.48 b | 43.44±1.67 a |
| Nodule | ||
| Ψsnodule (MPa) | –0.88±0.005 a | –1.20±0.01 b |
| Rnodule (μmol m−2 s−1) | –5.41±1.49 a | –2.11±0.62 b |
| Nase (μmol C2H2 g−1 DW h−1) | 41.80±7.84 a | 10.05±1.23 b |