. 2019 Oct 23;42(1):44–51. doi: 10.1016/j.pld.2019.09.004

Table 1.

Effects of ambient CO₂ concentration (400 μmol mol⁻¹) and elevated CO₂ concentration (800 μmol mol⁻¹) on the photosynthetic parameters of soybean plants at different growth stages. The values in the same column with different letters are significantly different (P < 0.05). Data are mean ± S.D. (n = 5 or 6); experiments were repeated three times. P_n, net photosynthesis; G_s, stomatal conductance; T_r, transpiration rate; WUE, water-use efficiency; C_i, intercellular CO₂ concentration; C_a, atmospheric CO₂ concentration; V1, first fully developed trifoliate leaves; R2, leaves from full flowering soybeans; R4, leaves from full pod stage of soybean.

Growth stage	CO₂ treatment	P_n (μmol CO₂/m²/s)	G_s (mol H₂O/m²/s)	T_r (mmol H₂O/m²/s)	WUE (mmol/mol)	C_i/C_a
V1	Ambient	14.03 ± 1.08^d	0.26 ± 0.02^abc	4.34 ± 0.24^a	3.23 ± 0.21^c	0.73 ± 0.02^c
V1	Elevated	18.04 ± 1.46^c	0.23 ± 0.11^bc	3.44 ± 1.10^b	5.58 ± 1.32^ab	0.77 ± 0.07^abc
R2	Ambient	14.95 ± 0.61^d	0.22 ± 0.02^c	3.95 ± 0.31^ab	3.80 ± 0.32^c	0.67 ± 0.03^d
R2	Elevated	26.43 ± 0.81^a	0.31 ± 0.07^ab	4.35 ± 0.75^a	6.24 ± 1.10^a	0.78 ± 0.04^ab
R4	Ambient	14.59 ± 0.74^d	0.28 ± 0.03^abc	4.17 ± 0.35^ab	3.52 ± 0.35^c	0.74 ± 0.03^bc
R4	Elevated	21.37 ± 0.70^b	0.30 ± 0.06^ab	4.32 ± 0.57^a	5.01 ± 0.68^b	0.81 ± 0.03^a