Table 2. Effect of FACE Treatment on Productive Parameters of Common Wheat.

experiment	factor	source of variation	above ground biomass (t ha–1 d.m.)	plant height (cm)	grain yield (t ha–1 d.m.)	harvest index	ear density (n° m–2)	TKWg (g)	GNYg (kg N ha–1)
1a	CO2b	a[CO2]	14.0 b	82.0 b	6.7 b	0.49 a	693 b	37.5 a	167 a
		e[CO2]	16.7 a	84.1 a	7.8 a	0.47 a	874 a	36.4 b	181 a
		P (F)c	<0.001	<0.001	<0.001	0.073	<0.001	0.006	0.073
		semd	0.2	2.6	0.1	0.024	218	1.7	32
	yeare	Y1	19.3 a	86.9 a	8.7 a	0.45 b	784 a	33.9 c	193 a
		Y2	12.1 c	75.4 b	7.0 b	0.58 a	913 a	36.7 b	167 a
		Y3	14.6 b	86.9 a	6.0 c	0.41 c	558 b	40.4 a	166 a
		P (F)	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	0.079
		sem	0.2	3.2	0.1	0.03	267	2.1	39
	CO2 X year	P (F)	0.026	0.012	0.099	0.227	0.653	0.403	0.351
		sem	0.314	4.51	0.2	0.042	378	3.0	55
2f	CO2	a[CO2]	15.0 b	91.2 b	6.3 b	0.42 b	546 b	47.3 a	162 b
		e[CO2]	17.7 a	94.3 a	7.9 a	0.44 a	606 a	45.5 b	191 a
		P (F)	<0.001	<0.001	<0.001	0.013	0.017	0.008	<0.001
		sem	1.7	2.6	0.7	0.027	87	2.4	17
	cultivar (cv)	Bologna	14.6 b	86.9 c	6.0 b	0.41 b	579 a	40.4 d	166 b
		Apache	17.8 a	98.3 b	8.0 a	0.45 a	588 a	50.8 b	187 a
		QH529	14.3 b	82.0 d	5.8 b	0.41 b	579 a	44.7 c	138 c
		Hystar	18.7 a	103.9 a	8.4 a	0.45 a	559 a	55.6 a	189 a
		P (F)	<0.001	<0.001	<0.001	<0.001	0.842	<0.001	<0.001
		sem	2.4	3.6	0.9	0.038	107	3.4	24
	CO2X cv	P (F)	0.107	0.072	0.014	0.220	0.882	0.420	0.031
		sem	3.4	5.1	1.3	0.054	151	4.8	34

^aExperiment carried out in three growing seasons on cv Bologna

^ba[CO₂] = ambient atmospheric carbon dioxide concentration, e[CO₂] = elevated carbon dioxide concentration

^cMeans followed by different letters are significantly different (the level of significance is shown in the table). Reported values are based on four replications.

^dsem: standard error of mean

^eY1, 2011–12; Y2, 2012–13; Y3, 2015–16

^fExperiment carried out in the 2015–16 growing season

^gTKW, thousand kernel weight; GNY, grain nitrogen yield