Table 2. Means (±SE) of thermal acclimation-related traits of two hybrid poplar clones (M×B and M×N) grown at day/night temperature of 23/18°C and 33/27°C under high (HN) and low (LN) nitrogen levels (n = 3).
| Clone M×B | Clone M×N | |||||||
|---|---|---|---|---|---|---|---|---|
| 23°C | 33°C | 23°C | 33°C | |||||
| HN | LN | HN | LN | HN | LN | HN | LN | |
| Topt(An) | 23.1 (1.2)bc | 24.1 (1.2)b | 30.3 (1.3)a | 29.3 (1.3)a | 20.5 (1.2)c | 19.7 (1.3)c | 30.1 (1.3)a | 26.1 (1.3)b |
| An_opt | 10.1 (0.8)b | 7.1(0.8)d | 14.9 (0.8)a | 9.3 (0.8)cb | 15.1 (0.8)a | 9.1 (0.8)c | 14.2 (0.8)a | 10.9 (0.8)b |
| An_growth | 10.6(1.0)b |
6.9(0.9)c | 13.9(1.1)a | 8.9(1.1)c | 14.9(1.1)a | 9.6(0.9)c | 13.4(1.1)a | 9.5(1.1)c |
| Rd25 | 2.02(0.2)c | 1.51(0.2)d | 2.41(0.2)bc | 2.61(0.2)b | 3.56(0.2)a | 2.39(0.2)bc | 2.66(0.2)b | 2.01(0.2)c |
| Q10 (Rd) | 1.9(0.1)b | 1.8(0.1)b | 2.0(0.1)a | 1.9(0.1)b | 2.0(0.1)a | 2.2(0.1)a | 1.8(0.1)b | 1.8(0.1)b |
| gs_growth | 0.16(0.01)c | 0.17(0.01)bc | 0.26(0.01)a | 0.20(0.01)b | 0.20(0.01)b | 0.16(0.01)c | 0.18(0.01)bc | 0.13(0.01)d |
| Topt(apparent Vcmax) | 33(1.5) | - | NA | NA | 34(1.2) | - | NA | NA |
| Ea(apparent Vcmax) | 75 (3)a | - | 49(3)b | 57(3)b | 58(3)b | - | 54(3)b | 55(3)b |
| Topt(apparent J) | 34 (1.9) | - | NA | NA | 30(1.1) | - | NA | NA |
| Ea(apparent J) | 46(2)a | - | 32(2)b | 28(2)b | 34(2)ab | - | 28(2)b | 33(2)b |
| apparent Jmax25: apparent Vcmax25 | 2.43(0.1)ab | 1.68(0.15)c | 1.53(0.15)c | 1.81(0.19)bc | 2.68(0.15)a | 2.01 (0.15)bc | 2.42(0.19)ab | 1.95(0.16)b |
| SLA | 172(7)a | 132(7)cd | 154(8)b | 123(7)d | 143(7)b | 141(7)bc | 136(8)c | 112(8)e |
| Narea | 1.3(0.1)b | 0.8(0.1)d | 1.3(0.1)b | 0.8(0.1)d | 1.9(0.1)a | 1.1(0.1)c | 1.4(0.1)b | 1.1(0.1)c |
Within rows, means followed by the same letter do not differ significantly at α = 0.05 based on Tukey’s test. ANOVA results are given in S1 Table.