Table 1. Effect of elevated CO₂ on grain mineral concentration in broomcorn millet seeds.

Year	Treatment	N	P	K	Fe	Mn	Ca	Mg	Cu	Zn	B
		(g kg−1)			(mg kg−1)
2013	CK	21.1 ± 1.2	2.56 ± 0.16	2.10 ± 0.05	129.25 ± 18.52	7.18 ± 0.12	36.33 ± 0.88	649.17 ± 18.18	10.23 ± 1.03	58.85 ± 0.95	5.28 ± 0.72
	EC	17.6 ± 0.9	2.69 ± 0.15	2.85 ± 0.24	137.33 ± 23.84	10.17 ± 1.06	35.13 ± 1.46	1181.50 ± 212.28	13.70 ± 2.05	58.22 ± 1.83	5.55 ± 0.16
2015	CK	23.6 ± 0.5	2.39 ± 0.027	2.59 ± 0.06	91.52 ± 10.18	8.63 ± 0.10	32.7 ± 0.37	1215.25 ± 29.87	6.28 ± 0.25	47.78 ± 0.51	4.98 ± 0.45
	EC	22.3 ± 0.1	2.40 ± 0.068	2.42 ± 0.17	118.42 ± 21.22	9.25 ± 0.23	35.02 ± 1.69	1243.83 ± 66.40	8.38 ± 1.19	49.62 ± 1.08	6.45 ± 0.28
2016	CK	24.9 ± 0.3	2.38 ± 0.065	2.54 ± 0.08	125.18 ± 0.75	9.85 ± 0.28	32.95 ± 2.55	1176.33 ± 6.51	14.08 ± 4.47	59.07 ± 1.02	4.15 ± 0.56
	EC	24.3 ± 0.1	2.43 ± 0.083	2.39 ± 0.05	94.90 ± 4.24	10.00 ± 0.30	32.98 ± 0.97	1149.17 ± 42.97	9.37 ± 0.46	60.98 ± 1.13	5.47 ± 0.14
ANOVA	Year	***	ns	ns	ns	*	ns	**	ns	ns	ns
	CO2	***	ns	ns	ns	**	ns	*	ns	ns	**
	CO2× year	*	ns	**	ns	*	ns	**	ns	ns	ns

Notes.

Values are means ± standard error of variables across the three replicates, and the statistical significance level P values for the effects of CO₂ treatment, year and their interaction.

CK

ambient atmospheric CO₂ concentration

EC

elevated atmospheric CO₂ concentration

ns

means not significant (P > 0.05)

^*significant at P < 0.05.

^**significant at P < 0.01.

^***significant at P < 0.001.