Table 3.

Effect of mycorrhizal inoculation (AMF), date of inoculation (days after seeding) and nitrogen (N) form on nitrogen, phosphor (P), and potassium (K) content (% in the dry mass of onion bulbs (cv. Stuttgarter Riesen) analyzed after a growing period of 149 days in a three factorial ANOVA based on an orthogonal design with six replications. Means ± standard deviation followed by the same letter do not differ significantly according to Duncan’s multiple range test. Probability levels written in italics indicate significant differences at a significance level of α = 0.05

AMF (v/v %)	Date (days)	N form	N (mg g−1)	N (g plant−1)	P (mg g−1)	P (g plant−1)	K (mg g−1)	K (g plant−1)
0			20.65 ± 1.2 b	1.24 ± 0.28 b	2.33 ± 0.30 b	0.15 ± 0.02	16.90 ± 1.6	0.99 ± 0.29 b
0.3			21.62 ± 1.3 a	1.33 ± 0.32 ab	2.66 ± 0.42 a	0.15 ± 0.03	17.00 ± 1.58	1.07 ± 0.34 ab
3.0			21.47 ± 1.9 a	1.39 ± 0.25 a	2.62 ± 0.41 a	0.15 ± 0.04	16.91 ± 0.99	1.15 ± 0.26 a
	0		21.90 ± 1.4 a	1.32 ± 0.31	2.65 ± 0.42 a	0.16 ± 0.04	17.44 ± 2.01 a	1.06 ± 0.3
	65		20.60 ± 1.7 b	1.32 ± 0.26	2.43 ± 0.33 b	0.15 ± 0.03	16.43 ± 0.98 b	1.08 ± 0.3
		NO3 –a	19.72 ± 1.5 b	1.11 ± 0.19 b	2.37 ± 0.33 b	0.13 ± 0.02	16.99 ± 1.10	1.33 ± 0.18 a
		NH4 +b	22.77 ± 1.7 a	1.54 ± 0.19 a	2.70 ± 0.40 a	0.18 ± 0.02	16.88 ± 1.78	0.82 ± 0.14 b
0	0	NO3 −	20.30 ± 1.3 cde	1.50 ± 0.17c	2.33 ± 0.22 bc	0.17 ± 0.015 bc)	17.66 ± 1.36	1.30 ± 0.13c
0.3			20.20 ± 1.9 def	1.47 ± 0.19	2.45 ± 0.36 bc	0.18 ± 0.02 ab	17.0 ± 0.89	1.24 ± 0.19
3.0			20.50 ± 1.7 cde	1.61 ± 0.19	2.66 ± 0.29 ab	0.19 ± 0.029 a	16.66 ± 1.21	1.38 ± 0.19
0	0	NH4 +	22.16 ± 1.1 bc	1.23 ± 0.23	2.48 ± 0.23 bc	0.12 ± 0.014 c	17.16 ± 1.72	0.93 ± 0.17
0.3			24.66 ± 1.9 a	1.11 ± 0.13	3.02 ± 0.39 a	0.13 ± 0.024 c	18.16 ± 1.47	0.75 ± 0.08
3.0			23.33 ± 1.3 ab	1.17 ± 0.13	2.95 ± 0.26 a	0.13 ± 0.019 c	17.66 ± 0.81	0.77 ± 0.11
0	65	NO3 −	18.60 ± 1.2 f		2.12 ± 0.36 c		16.66 ± 1.21
0.3			19.50 ± 1.5 ef		2.51 ± 0.31 bc		16.33 ± 1.03
3.0			19.0 ± 0.89 ef		2.16 ± 0.12 c		17.16 ± 0.75
0	65	NH4 +	21.50 ± 1.5b bcd		2.41 ± 0.27 bc		16.0 ± 1.67
0.3			22.16 ± 0.9 bc		2.66 ± 0.47 ab		16.5 ± 2.25
3.0			22.83 ± 1.7 b		2.70 ± 0.48 ab		15.83 ± 1.83
Source of variation			Probability level
AMF			0.050	0.025	0.004	0.22	0.972	0.003
Date			< 0.001	0.963	0.01	0.305	0.006	0.682
N form			< 0.001	< 0.001	< 0.001	< 0.001	0.765	< 0.001
AMF × date			0.854	0.437	0.410	0.113	0.928	0.258
AMF × N form			0.368	0.105	0.652	0.050	0.275	0.154
Date × N form			0.824	0.215	0.981	0.180	0.123	0.862
AMF × date × N form			0.034	0.577	0.049	0.624	0.622	0.094

^aNO₃ ⁻ predominant = 95% NO₃ ⁻/5% NH₄ ⁺

^bNH₄ ⁺ predominant = 25% NO₃ ⁻/75% NH₄ ⁺

^cOnly the results of the AMF × N form interaction are presented averaged over the dates