Table 4 Effects of elevated CO2 concentrations on carbon and nitrogen contents of soybean
Element (mg g−1 DW) | CO2 concentrations (ppm) | p value | |||||||
|---|---|---|---|---|---|---|---|---|---|
400 | 600 | 800 | 1000 | 1200 | 1400 | 1600 | |||
Leaf | C | 403.6 ± 0.33(a) | 386.14 ± 0.23(d) | 390.54 ± 0.24 (d) | 373.66 ± 12.73 (c) | 393.30 ± 0.70 (bd) | 392.07 ± 0.50 (bd) | 395.71 ± 0.37(ab) | p < 0.001 |
N | 32.04 ± 0.12 (bc) | 30.56 ± 0.22 (d) | 33.56 ± 0.16 (a) | 31.61 ± 1.00 (c) | 34.04 ± 0.12 (a) | 32.61 ± 0.07 (b) | 30.83 ± 0.2 (d) | p < 0.001 | |
C/N | 12.60 ± 0.05 (b) | 12.64 ± 0.10 (b) | 11.64 ± 0.06 (e) | 11.82 ± 0.03 (d) | 11.55 ± 0.03 (e) | 12.02 ± 0.04 (c) | 12.84 ± 0.08 (a) | p < 0.001 | |
Stem | C | 375.71 ± 0.66 (a) | 358.33 ± 0.47 (b) | 348.84 ± 0.17(d) | 347.86 ± 0.20 (e) | 335.51 ± 0.05 (g) | 339.93 ± 1.01(f) | 359.40 ± 0.30 (c) | p < 0.001 |
N | 26.47 ± 0.14(g) | 32.58 ± 0.19 (f) | 43.24 ± 0.25 (b) | 45.85 ± 0.41 (a) | 37.51 ± 0.10 (d) | 42.24 ± 0.12 (c) | 36.94 ± 0.20 (e) | p < 0.001 | |
C/N | 14.19 ± 0.09 (a) | 10.10 ± 0.06 (b) | 8.07 ± 0.05 (e) | 7.59 ± 0.07 (f) | 8.95 ± 0.023.6 (d) | 8.05 ± 0.04 (e) | 9.73 ± 0.06 (c) | p < 0.001 | |
Root | C | 352.38 ± 0.13 (cd) | 347.81 ± 0.42 (d) | 350.68 ± 0.18 (cd) | 354.78 ± 0.52 (c) | 376.80 ± 0.62 (ab) | 378.59 ± 2.97 (a) | 371.19 ± 8.64 (b) | p < 0.001 |
N | 26.08 ± 0.29 (c) | 34.40 ± 0.19 (b) | 38.35 ± 0.09 (a) | 37.70 ± 0.10 (a) | 36.79 ± 0.25(a) | 37.57 ± 0.33 (a) | 33.59 ± 3.33 (b) | p < 0.001 | |
C/N | 13.51 ± 0.15 (a) | 10.11 ± 0.06 (c) | 9.14 ± 0.02 (d) | 9.41 ± 0.03 (d) | 10.24 ± 0.08 (c) | 10.07 ± 0.01 (c) | 11.10 ± 0.81 (b) | p < 0.001 | |