Table 4.

Nitrate percentage of inorganic N pool and potential net nitrification rates in root-zone soils of field-grown plants of BNI isogenic lines, MUNAL control versus BNI-MUNAL after 21-d incubation period ( SI Appendix, Study 6a)

Wheat genetic stocks	Soil ammonium (μg ⋅ g−1 soil)		Soil nitrate (μg ⋅ g−1 soil)		Total inorganic N (NH4 + + NO3 −) μg ⋅ g−1 soil		Nitrate percentage of inorganic N pool (%)		Potential net nitrification rate (μg ⋅ NO3 − ⋅ g−1 soil ⋅ d−1)
	Mean	SE	Mean	SE	Mean	SE	Mean	SE	Mean	SE
MUNAL control	86.4	3.2	505.0	31.1	591.4	28.2	85.4	1.2	24.05	0.74
BNI-MUNAL	245.0	23.0	422.5	22.2	667.5	15.0	63.3	3.2	20.10	0.52
SE of LS mean (based on two-way analysis GLM using SYSTAT 14.0)	8.9**		18.1*				1.44**		0.87*

The nitrate percentage of inorganic N pool is calculated as [soil − NO₃ ⁻/(soil NO₃ ⁻+ soil NH₄ ⁺)] × 100], that is, proportion of nitrate to total inorganic N. Initial soil inorganic nitrogen levels (NO₃ ⁻ and NH₄ ⁺) are deducted before calculating net change in soil inorganic N forms during the incubation period. Potential net nitrification rate = [soil nitrate levels at the end of incubation period (i.e., at 21 d) – soil nitrate levels at the beginning of incubation period (i.e., time “0”)]/21. Based on Holm–Sidak test; **significant at P < 0.001; *significant at P < 0.05. Values are means ± SE of four replications.