Table 4.

Effect of mycorrhizal inoculation (AMF), date of inoculation (days after seeding), and nitrogen (N) form on the most important flavonols in bulbs of onion plants (cv. Stuttgarter Riesen) 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	QDGc (μmol g−1)	QMG d (μmol g−1)	IMGe (μmol g−1)
0			69.1 ± 17.1	30.9 ± 11.2	4.20 ± 1.3
0.3			67.4 ± 22.7	29.4 ± 11.0	3.90 ± 1.8
3.0			79.1 ± 32.0	40.9 ± 16.8	4.40 ± 2.2
	0		65.9 ± 19.1	30.2 ± 11.4	4.23 ± 1.8
	65		77.9 ± 27.7	37.0 ± 14.9	4.15 ± 1.8
		NO3 –a	69.5 ± 24.8	33.4 ± 14.0	3.67 ± 1.6
		NH4 + b	74.3 ± 24.2	33.7 ± 13.7	4.51 ± 1.9
0	0	NO3 −	62.4 ± 18.7 bc	30.7 ± 8.8 bc	3.72 ± 1.4 bcf
0.3			51.9 ± 8.27 c	21.0 ± 5.19 c	5.05 ± 2.2 a
3.0			71.4 ± 34.4 abc	38.3 ± 12.3 abc	3.43 ± 1.6 d
0	0	NH4 +	66.6 ± 15.0 bc	26.6 ± 10.8 bc	3.42 ± 1.1 d
0.3			69.0 ± 22.9 abc	31.2 ± 19.7 bc	4.38 ± 1.4 b
3.0			74.1 ± 25.3 abc	33.0 ± 12.1 bc	4.64 ± 1.9 ab
0	65	NO3 −	74.1 ± 16.2 abc	33.8 ± 17.8 bc
0.3			85.5 ± 21.6 ab	37.5 ± 12.4 abc
3.0			71.7 ± 24.6 abc	39.3 ± 13.1 ab
0	65	NH4 +	73.4 ± 7.19 abc	32.5 ± 5.42 bc
0.3			63.2 ± 26.9 bc	27.8 ± 7.44 bc
3.0			99.4 ± 37.6 a	50.9 ± 18.4 a
Source of variation			Probability level
AMF			0.031	0.009	0.725
Date			0.033	0.025	0.859
N form			0.382	0.940	0.153
AMF × date			0.934	0.804	0.856
AMF × N form			0.400	0.742	0.042
Date × N form			0.561	0.984	0.786
AMF × date × N form			0.044	0.048	0.129

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

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

^cQDG = quercetin-3,4′-di-O-β-d-glucoside

^dQMG = quercetin-4′- O-β-d-glucoside

^eIMG = isorhamnetin-4′-O-β-d-glucoside

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