Table I. Impact of water deficit on a set of physiological, growth, and morphological parameters.
All measurements were performed 10 d after the onset of water deficit (except for dry weight at bolting). Rosette relative growth rate was measured from three consecutive evaluations of rosette dry weight. Photosynthesis and stomatal conductance were measured at growth light intensity on the youngest fully expanded leaves. Photosynthesis at saturating light (Amax) was measured at 1,000 μmol m−2 s−1. Specific leaf area, leaf thickness, water content, and relative water content were measured on the youngest fully expanded leaves on samples harvested at the end of the photoperiod. Protein content was measured on total rosettes. Data are means and (sd) of eight to 12 plants or leaves. Letters refer to lsd grouping following ANOVA for all variables except relative growth rate, where statistics are based on ANCOVA.
| Parameter | Unit | Treatment | ||
| Well Watered | Moderate Water Deficit | Severe Water Deficit | ||
| Relative growth rate | mg dry weight mg−1 dry weight d−1 | 0.182 a | 0.144 b | 0.119 c |
| Rosette dry weight | mg | 14.9 (1.8) a | 10.0 (1.8) b | 8.5 (1.4) b |
| Rosette dry weight at bolting | mg | 204 (17) a | 117 (14) b | 53 (4) c |
| Net photosynthesis | μmol m−2 s−1 | 4.70 (0.61) a | 4.93 (1.17) a | 4.66 (0.81) a |
| Amax | μmol m−2 s−1 | 10.35 (0.85) a | 10.3 (1.15) a | 7.6 (0.53) b |
| Dark respiration | μmol m−2 s−1 | 1.11 (0.2) a | 1.19 (0.12) a | 1.30 (0.18) a |
| Stomatal conductance | mmol m−2 s−1 | 488 (53) a | 347 (27) b | 183 (47) c |
| Protein content | mg g−1 dry weight | 153 (8.0) a | 144 (8.8) ab | 139.3 (20) bc |
| Specific leaf area | mm2 mg−1 dry weight | 45 (5.2) a | 43 (4.5) ab | 36 (3.7) b |
| Leaf thickness | μm | 186 (22) a | 197 (18) b | 208 (16) c |
| Water content | g water g−1 fresh weight | 0.92 (0.01) a | 0.89 (0.01) b | 0.86 (0.02) c |
| Relative water content | g water g−1 water at saturation | 0.92 (0.03) a | 0.84 (0.04) b | 0.71 (0.04) d |