Table 4.

Chlorophyll content, stomatal conductance (g_s), N and C content, and N and C isotope composition (δ¹⁵N and δ¹³C, respectively) in four durum wheat genotypes grown under ambient or elevated [CO₂] and well-watered or severe water stress conditions (100 vs. 30% pot capacity).

	Genotype	Ambient [CO2]		Elevated [CO2]		PC	PW	PC × W
		Well-watered	Water stressed	Well-watered	Water stressed
Chlorophyll (SPAD units)	Mexa	55.8	55.0	52.7	52.7	0.100	0.790	0.807
	Regallo	50.6	43.1	46.6	45.8	0.877	0.351	0.439
	Burgos	56.6	53.2	53.3	58.4	0.661	0.683	0.076
	Ramirez	52.7	51.6	52.8	49.0	0.532	0.230	0.500
gs(mmol m−2 s−1)	Mexa	81.9	55.0	223.5	91.5	0.112	0.150	0.323
	Regallo	101.8	82.3	64.4	32.2	0.265	0.499	0.866
	Burgos	245.0	96.7	247.0	30.7	0.390	<0.001	0.362
	Ramirez	44.0	52.5	151.3	57.2	0.160	0.270	0.194
N (%)	Mexa	4.39	4.67	4.10	4.54	0.491	0.257	0.785
	Regallo	4.68	4.33	4.37	3.78	0.017	0.011	0.424
	Burgos	4.89	4.66	4.15	3.97	0.013	0.398	0.918
	Ramirez	3.81	4.22	4.16	4.43	0.521	0.437	0.872
δ15N(‰)	Mexa	2.71	2.74	3.52	3.59	0.060	0.895	0.950
	Regallo	3.78	3.27	3.55	3.58	0.947	0.685	0.646
	Burgos	2.45	2.67	3.69	3.47	0.018	0.997	0.547
	Ramirez	2.69	2.99	3.23	2.73	0.508	0.641	0.084
C (%)	Mexa	41.8	41.8	41.3	41.9	0.490	0.368	0.439
	Regallo	39.9	38.0	40.4	41.1	0.064	0.476	0.165
	Burgos	41.9	41.4	41.8	41.3	0.877	0.590	0.968
	Ramirez	41.4	40.7	40.9	42.1	0.416	0.658	0.115
δ13C(‰)	Mexa	−32.3	−31.4	−56.9	−56.4	<0.001	0.546	0.851
	Regallo	−33.5	−32.2	−54.4	−54.0	0.001	0.850	0.927
	Burgos	−32.8	−32.4	−46.1	−46.3	0.004	0.979	0.940
	Ramirez	−31.9	−32.6	−59.1	−56.4	<0.001	0.752	0.594

Significant effects for elevated [CO₂] (C), water stress (W) and their interaction (C × W) were determined by two-factor ANOVA (P). Significant P values are marked in bold (P < 0.05).