Table 4.

Abundance of nitrifier (amoA) and denitrifier (nosZ) genes under elevated CO₂ and O₃ treatments in the rhizosphere and bulk soil during the 2008 growing season at three sampling times (V4 = Fourth trifoliate leaf; R4 = Full pod; R8 = Full maturity). Values are means with standard errors in parentheses (n = 4).

Soil environment	Treatment	amoA (copies g−1 soil)			nosZ (copies g−1 soil)
		V4	R4	R8	V4	R4	R8
Rhizosphere	Ambient	1.2 × l07 (2.3 × 106)	9.2 × 106 (3.8 × 105)	7.6 × 106 (1.3 × 106)	2.6 × 106 (6.2 × 105)	3.7 × 106 (8.3 × 105)	7.2 × 105 (1.4 × 105)
	CO2	1.3 × 107 (1.1 × 106)	6.5 × 106 (4.3 × 10s)	9.5 × 106 (2.4 × 106)	1.9 × 106 (6.3 × 105)	1.6 × 106 (5.5 × 105)	8.9 × 105 (1.1 × 105)
	O3	1.5 × 107 (2.0 × 106)	1.1 × 107 (9.5 × 105)	8.8 × 106 (9.4 × 105)	4.2 × 106 (7.9 × 105)	1.2 × 106 (8.3 × 104)	1.3 × 106 (2.0 × 105)
	CO2 + O3	1.3 × 107 (1.5 × 106)	7.6 × 106 (1.0 × 106)	1.2 × 107 (2.5 × 106)	2.2 × 106 (5.3 × 105)	1.4 × 106 (1.9 × 105)	1.2 × 106 (1.8 × 105)
Bulk soil	Ambient	1.2 × 107 (6.5 × 105)	8.4 × 106 (1.2 × 106)	5.1 × 106 (9.7 × 105)	1.0 × 106 (2.3 × 105)	1.2 × 106 (2.1 × 105)	7.0 × 105 (2.2 × 105)
	CO2	8.0 × 106 (6.5 × 105)	1.4 × 107 (1.0 × 106)	1.1 × 107 (1.3 × 106)	2.9 × 105 (8.8 × 104)	1.9 × 106 (5.8 × 105)	9.1 × 105 (1.3 × 105)
	O3	1.0 × 107 (2.1 × 105)	1.0 × 107 (1.3 × 106)	6.7 × 106 (6.8 × 105)	1.8 × 106 (5.3 × 105)	2.5 × 106 (9.2 × 105)	7.5 × 105 (1.1 × 105)
	CO2 + O3	1.1 × 107 (1.6 × 106)	7.3 × 106 (7.6 × 105)	8.0 × 106 (2.4 × 105)	2.8 × 106 (7.3 × 105)	2.3 × 106 (4.5 × 105)	7.7 × 105 (1.0 × 105)