. 2013 Feb 1;64(6):1485–1496. doi: 10.1093/jxb/ert005

Table 3.

Light saturated rate of net assimilation (A _sat), stomatal conductance (g _s), intercellular CO₂ concentration (C _i) and intrinsic water-use efficiency (WUE_int) at instantaneous level in leaf 3 and leaf 4 of an old (released in 1961) and a modern (released in 1997) winter wheat cultivar exposed to elevated CO₂ and/or O₃ for 21 d in OTCs. The leaf chamber CO₂ concentration was maintained at 400 ppm during gas exchange measurements: control (CO₂, 385±4 ppm+CFA, 4±0.02 ppb O₃); elevated CO₂ (CO₂, 714±16 ppm+CFA, 4±0.02 ppb O₃); O₃ (ambient CO₂, 385±4 ppm+elevated O₃, 72±5 ppb O₃ for 7h d^–1, 9.00–16.00h); and elevated CO₂+O₃ (elevated CO₂, 714±16 ppm+elevated O₃, 72±5 ppb for 7h d^–1). Overall, elevated CO₂ significantly increased A _sat (P <0.01) and g _s (P <0.1) in both matured and young leaves, but decreased WUE_int in the young leaf. Exposure to O₃ significantly decreased A _sat (P <0.001), but increased C _i (P <0.1) in the matured leaf. Elevated O₃ did not alter A _sat but decreased g _s (P <0.05) and increased WUE_int (P <0.001) in the young leaf. Results are shown as means±1 standard error (n=8). Means with the same letter were not significantly different.

Treatment	A _sat (µmol m^–2 s^–1)		g _s (mol m^–2 s^–1)		C _i (ppm)		WUE_int (µmol mol^–1)
Treatment	Leaf 3	Leaf 4	Leaf 3	Leaf 4	Leaf 3	Leaf 4	Leaf 3	Leaf 4
(a) Beijing 6 (1961)
Control	8.68±0.63^a	14.73±0.85^ab	0.20±0.02^ab	0.28±0.01^bc	333±8^bc	393±6^a	43.30±4.41^ab	52.89±3.43^bc
CO₂	8.31±0.60^a	14.38±0.76^ab	0.19±0.02^ab	0.28±0.01^bc	331±8^bc	348±5^cd	44.05±4.31^ab	52.89±3.07^bc
O₃	3.75±0.48^b	13.50±0.98^b	0.13±0.02^b	0.16±0.01^d	360±5^a	359±7^bcd	31.11±3.54^b	82.71±3.97^a
CO₂+O₃	8.55±0.52^a	16.50±0.76^a	0.17±0.02^ab	0.29±0.01^bc	321±5^c	360±5^bc	51.24±4.84^a	56.66±3.07^b
(b) Zhongmai 9 (1997)
Control	8.93±0.75^a	15.55±0.76^ab	0.21±0.02^ab	0.32±0.01^ab	332±9^bc	388±5^a	43.30±4.35^ab	49.23±3.31^bc
CO₂	10.08±0.73^a	16.70±0.74^a	0.25±0.02^a	0.32±0.01^ab	334±8^bc	342±5^d	40.68±4.40^ab	51.90±3.34^bc
O₃	4.87±0.53^b	13.70±0.71^b	0.16±0.02^ab	0.24±0.01^c	352±8^ab	391±5^a	36.20±4.40^ab	59.47±3.36^b
CO₂+O₃	10.08±0.60^a	15.87±0.77^ab	0.25±0.02^a	0.37±0.01^a	334±9^bc	368±5^b	40.72±4.39^ab	42.64±3.30^c