Table 2.
Mean values for water-use efficiency (WUE): (i) measured from the biomass accumulated and total water transpired (WUEbiomass); and (ii) calculated from the gas exchange measurements (WUEintrinsic and WUEinstantaneous), carbon isotope discrimination (Δ13C) of the spike (Δ13Csp), flag (Δ13Cf), root (Δ13Cr), and shoot (Δ13Cs), and the oxygen isotope enrichment above source water in shoots (Δ18Os) of four wheat genotypes (G) subjected to different water regimes (WR) and grown under low and high N
| WUEbiomass | WUEintrinsic | WUEinstantaneous | Δ13Csp | Δ13Cf | Δ13Cr | Δ13Cs | Δ18Os | Δ13Cs/Δ18Os | |
| Low N | |||||||||
| WR | |||||||||
| 40% | 2.2 b | 53.9 a | 5.3 a | 18.0 a | 20.4 a | 18.9 a | 19.6 a,b | 35.8 a | 0.55 a |
| 70% | 2.4 b | 52.5 a | 5.3 a | 18.2 a | 20.7 a | 19.1 a | 19.7 a | 35.1 a,b | 0.56 a |
| 100% | 2.9 a | 60.3 a | 5.9 a | 17.5 b | 19.9 b | 18.9 a | 19.2 c | 34.5 b | 0.56 a |
| G | |||||||||
| Mexa | 2.3 b | 54.5 a | 5.4 a,b | 18.5 a | 21.2 a | 19.5 a | 20.0 a | 35.2 a | 0.57 a |
| Bic-1 | 2.3 b | 52.7 a | 5.1 b | 17.9 b | 20.2 b | 19.0 b | 19.5 b | 35.2 a | 0.56 a |
| L/H | 2.5 a | 57.0 a | 5.1 b | 17.6 b | 20.0 b | 18.5 c | 19.1 b | 35.0 a | 0.55 a |
| Omr-3 | 2.6 a | 58.0 a | 6.4 a | 17.6 b | 19.9 b | 18.8 a,b | 19.3 b | 35.3 a | 0.55 a |
| High N | |||||||||
| WR | |||||||||
| 40% | 3.5 a | 78.7 a | 6.9 a | 16.1 b | 18.3 b | 18.0 a,b | 17.8 b | 35.6 a | 0.50 b |
| 70% | 3.6 a | 74.2 a,b | 6.9 a | 16.1 b | 18.4 b | 17.9 b | 17.8 b | 34.9 a | 0.52 b |
| 100% | 3.6 a | 66.0 b | 6.5 a | 16.7 a | 18.9 a | 18.3 a | 18.6 a | 33.8 b | 0.55 a |
| G | |||||||||
| Mexa | 3.0 c | 60.6 b | 6.0 a | 17.6 a | 20.3 a | 19.0 a | 19.3 a | 34.6 a | 0.56 a |
| Bic-1 | 3.6 b | 71.2 b,c | 6.8 a | 16.2 b | 18.1 c | 18.1 b | 18.1 b | 34.6 a | 0.52 b |
| L/H | 3.5 b | 75.3 a,b | 6.9 a | 16.6 b | 18.8 b | 18.1 b | 18.1 b | 35.1 a | 0.52 b |
| Omr-3 | 4.3 a | 86.6 a | 7.5 a | 14.8 c | 16.9 d | 17.3 c | 16.8 c | 34.7 a | 0.48 c |
Data are the mean of 16 (WR) or 12 (G) replicates. Within each nitrogen treatment and within each water regime (40, 70, and 100% CC) or genotype (Mexa, Bicrecham-1, Lahn/Haucan, and Omrabi-3), values with different letters are significantly different according to the Tukey-b test (P <0.05).