Table 1. Measured variables (means ± SE) of the four Anisodus species under each of the three soil water treatments: Low stress (80% of maximum field capacity, FC), Moderate stress (50% FC) and High stress (20% FC).
| Variable and species | Water treatments (% of maximum FC) |
||
|---|---|---|---|
| High stress | Moderate stress | Low stress | |
| (20% FC) | (50% FC) | (80% FC) | |
| Aboveground biomass (g) | |||
| A. tanguticus | 0.238 ± 0.017 A, X | 0.339 ± 0.039 A, X | 0.459 ± 0.053 A, Y |
| A. luridus | 0.839 ± 0.092 B, X | 1.306 ± 0.146 B, Y | 1.380 ± 0.113 B, Y |
| A. carniolicoides | 0.857 ± 0.111 B, X | 1.185 ± 0.109 B, X | 2.472 ± 0.293 C, Y |
| A. acutangulus | 0.912 ± 0.075 B, X | 1.436 ± 0.109 B, Y | 2.187 ± 0.129 C, Z |
| Belowground biomass (g) | |||
| A. tanguticus | 0.088 ± 0.010 A, X | 0.101 ± 0.016 A, X | 0.097 ± 0.017 A, X |
| A. luridus | 0.115 ± 0.018 A, X | 0.325 ± 0.088 B, Y | 0.229 ± 0.037 AC, XY |
| A. carniolicoides | 0.087 ± 0.018 A, X | 0.116 ± 0.013 A, X | 0.422 ± 0.116 B, Y |
| A. acutangulus | 0.098 ± 0.011 A, X | 0.180 ± 0.018 A, Y | 0.314 ± 0.029 BC, Z |
| Total biomass (g) | |||
| A. tanguticus | 0.326 ± 0.025 A, X | 0.441 ± 0.053 A, XY | 0.557 ± 0.067 A, Y |
| A. luridus | 0.954 ± 0.108 B, X | 1.632 ± 0.198 B, Y | 1.609 ± 0.135 B, Y |
| A. carniolicoides | 0.944 ± 0.127 B, X | 1.301 ± 0.119 B, X | 2.893 ± 0.387 C, Y |
| A. acutangulus | 1.010 ± 0.086 B, X | 1.616 ± 0.120 B, Y | 2.500 ± 0.147 C, Z |
| Root:shoot ratio | |||
| A. tanguticus | 0.371 ± 0.027 A, X | 0.293 ± 0.030 A, Y | 0.208 ± 0.018 A, Z |
| A. luridus | 0.132 ± 0.008 B, X | 0.242 ± 0.057 A, Y | 0.163 ± 0.024 AB, XY |
| A. carniolicoides | 0.094 ± 0.009 B, X | 0.098 ± 0.006 B, X | 0.156 ± 0.024 AB, Y |
| A. acutangulus | 0.104 ± 0.005 B, X | 0.127 ± 0.010 B, XY | 0.144 ± 0.012 B, Y |
| Long-term water use efficiency (g∙kg−1) | |||
| A. tanguticus | 5.710 ± 1.079 A, X | 2.202 ± 0.522 A, Y | 1.113 ± 0.147 A, Y |
| A. luridus | 1.055 ± 0.128 B, X | 1.192 ± 0.041 B, X | 1.214 ± 0.074 AC, X |
| A. carniolicoides | 2.117 ± 0.598 B, X | 1.560 ± 0.124 B, X | 2.838 ± 0.307 B X |
| A. acutangulus | 1.217 ± 0.227 B, X | 1.527 ± 0.069 B, X | 1.629 ± 0.090 C, X |
| photosynthetic rate (μmol∙m−2 s−1) | |||
| A. tanguticus | 11.874 ± 0.336 A, X | 12.724 ± 0.519 A, X | 14.742 ± 0.485 A, Y |
| A. luridus | 9.763 ± 0.465 B, X | 17.703 ± 0.431 B, Y | 16.676 ± 0.202 B, Y |
| A. carniolicoides | 10.792 ± 0.423 AB, X | 12.793 ± 0.302 B, Y | 14.710 ± 0.510 A, Z |
| A. acutangulus | 10.555 ± 0.389 B, X | 12.248 ± 0.283 B, Y | 12.074 ± 0.293 C, Y |
| Stomatal conductance (mmol m−2 s−1) | |||
| A. tanguticus | 0.152 ± 0.015 A, X | 0.243 ± 0.023 A, Y | 0.297 ± 0.020 A, Y |
| A. luridus | 0.083 ± 0.006 B, X | 0.382 ± 0.026 B, Y | 0.400 ± 0.029 B, Y |
| A. carniolicoides | 0.168 ± 0.008 A, X | 0.215 ± 0.010 A, Y | 0.270 ± 0.020 AC, Z |
| A. acutangulus | 0.168 ± 0.018 A, X | 0.208 ± 0.012 A, XY | 0.234 ± 0.009 C, Y |
| Transpiration (mmol m−2 s−1) | |||
| A. tanguticus | 4.866 ± 0.366 A, X | 6.703 ± 0.447 AB, Y | 7.553 ± 0.276 AB, Y |
| A. luridus | 3.328 ± 0.232 B, X | 9.913 ± 0.356 C, Y | 10.026 ± 0.380 C, Y |
| A. carniolicoides | 5.165 ± 0.225 A, X | 7.184 ± 0.250 B, Y | 8.180 ± 0.328 A, Z |
| A. acutangulus | 5.055 ± 0.407 A, X | 6.048 ± 0.240 A, Y | 6.898 ± 0.149 B, Y |
| Instantaneous water use efficiency | |||
| A. tanguticus | 2.498 ± 0.164 A, X | 1.917 ± 0.059 AB, Y | 1.954 ± 0.032 A, Y |
| A. luridus | 2.972 ± 0.136 B, X | 1.791 ± 0.037 A, Y | 1.675 ± 0.063 B, Y |
| A. carniolicoides | 2.097 ± 0.065 C, X | 1.793 ± 0.079 A, Y | 1.817 ± 0.018 C, Z |
| A. acutangulus | 2.137 ± 0.140 AC, X | 2.039 ± 0.082 B, XY | 1.752 ± 0.042 BC, Y |
| Maximum quantum yield of PS II | |||
| A. tanguticus | 0.817 ± 0.005 A, X | 0.829 ± 0.002 AB, Y | 0.823 ± 0.002 A, XY |
| A. luridus | 0.830 ± 0.002 B, X | 0.834 ± 0.001 A, X | 0.831 ± 0.002 B, X |
| A. carniolicoides | 0.824 ± 0.002 AB, X | 0.823 ± 0.004 B, X | 0.829 ± 0.003 B, X |
| A. acutangulus | 0.827 ± 0.001 B, X | 0.831 ± 0.001 A, Y | 0.832 ± 0.001 B, Y |
| Carbon content | |||
| A. tanguticus | 0.441 ± 0.006 A, XY | 0.431 ± 0.008 A, X | 0.455 ± 0.009 A, Y |
| A. luridus | 0.424 ± 0.012 A, X | 0.413 ± 0.006 AB, X | 0.432 ± 0.007 BC, X |
| A. carniolicoides | 0.399 ± 0.010 A, X | 0.401 ± 0.011 B, X | 0.424 ± 0.004 C, X |
| A. acutangulus | 0.408 ± 0.029 A, X | 0.423 ± 0.008 AB, X | 0.437 ± 0.006 AC, X |
| Nitrogen use efficiency | |||
| A. tanguticus | 15.038 ± 0.347 A, X | 17.924 ± 0.255 A, X | 16.794 ± 0.310 A, X |
| A. luridus | 16.164 ± 0.494 A, X | 17.839 ± 0.482 A, Y | 18.115 ± 0.374 AC, Y |
| A. carniolicoides | 16.094 ± 0.613 A, X | 18.713 ± 0.565 A, Y | 18.836 ± 1.019 BC, Y |
| A. acutangulus | 17.570 ± 1.980 A, X | 17.714 ± 0.466 A, X | 16.983 ± 0.373 A, X |
| Carbon isotope composition | |||
| A. tanguticus | −29.583 ± 0.193 A, X | −30.572 ± 0.285 A, Y | −30.823 ± 0.504 A, Y |
| A. luridus | −28.675 ± 0.294 A, X | −30.173 ± 0.235 AB, Y | −30.191 ± 0.527 B, Y |
| A. carniolicoides | −28.630 ± 0.218 A, X | −29.555 ± 0.377 B, Y | −29.401 ± 0.581 C, XY |
| A. acutangulus | −26.793 ± 0.443 B, X | −28.600 ± 0.249 C, Y | −28.848 ± 0.406 C, Y |
Values with different letters (X, Y, Z) indicate a significant difference (P < 0.05) between water treatments, and those with different letters (A, B, C) indicate a significant difference (P < 0.05) between species, based on one-way ANOVA.