Table I. A mixed-model ANOVA on the effects of N source (NO₃⁻ or NH₄⁺) and atmospheric CO₂ concentration regime (ambient day and night, 390/390 µmol mol⁻¹; ambient during the day and elevated at night, 390/720 µmol mol⁻¹; elevated during the day and ambient at night, 720/390 µmol mol⁻¹; or elevated day and night, 720/720 µmol mol⁻¹) on various parameters of Arabidopsis and wheat (n = 10–16).

Dash, No data; ns, nonsignificant differences; *, P < 0.05; **, P < 0.01; ***, P < 0.001.

	Arabidopsis					Wheat
Main Effects	Plant Biomass	Shoot NO3−	Shoot Organic N	Root NO3−	Root Organic N	Plant Biomass	Shoot NO3−	Shoot Organic N	Root NO3−	Root Organic N
N	***	—	***	—	***	***	—	***	—	***
CO2	***	**	***	***	***	***	***	***	***	ns
N*CO2	***	—	***	—	ns	*	—	**	—	***