Table 1.

Shoot and rhizosphere gas exchange rates for 14-day-old wheat seedlings (T. aestivum L. cv. Veery 10)

N source	Photosynthesis			N2O-N emissions
	CO2, μmol⋅m−2⋅s−1	O2, μmol⋅m−2⋅s−1	AQ, CO2/O2	Shoot, pmol⋅m−2⋅s−1	Rhizosphere, pmol⋅g−1⋅s−1
50 μM (15NH4)2SO4	14.31  ± 1.32	12.06  ± 0.77	1.21  ± 0.06	ND	40.4  ± 2.1
100 μM K15NO3	15.32  ± 1.48	13.63  ± 0.84	1.13  ± 0.05	25.59  ± 1.68	304.1  ± 93.8

Shown for shoots are net photosynthetic CO₂ assimilation rates, net photosynthetic O₂ evolved, AQ (the ratio of CO₂ assimilated to O₂ evolved), and shoot N₂O emissions (mean ± SE, n = 11). Shown for the rhizosphere are N₂O production rates (n = 7).