. 2021 Jun 29;12:687622. doi: 10.3389/fpls.2021.687622

Table 5.

Summary of the analysis of variance (ANOVA) for nitrogen fertilization (N) and genotypic (G) effects on the NDVI (normalized difference vegetation index) and GGA (greener area), and the mean values across nitrogen fertilization levels for these vegetation indices.

Phenological stages	2017/18
	Level of significance (ANOVA)				Mean ± standard deviation of nitrogen levels
	Traits	N	G	N × G	N50	N100	N130
Tillering	GGA1	0.826^ns	0.000^∗∗∗	0.75^ns	0.03 ± 0.02a	0.03 ± 0.02a	0.03 ± 0.02a
Tillering	GGA2	0.559^ns	0.000^∗∗∗	0.29^ns	0.14 ± 0.08a	0.15 ± 0.08a	0.13 ± 0.07a
Stem elongation	GGA3	0.014^∗	0.000^∗∗∗	0.23^ns	0.42 ± 0.12b	0.54 ± 0.12a	0.50 ± 0.11a
	NDVI1	0.174^ns	0.000^∗∗∗	0.39^ns	0.48 ± 0.09a	0.50 ± 0.08a	0.48 ± 0.07a
	NDVI2	0.049^∗	0.000^∗∗∗	0.16^ns	0.62 ± 0.10b	0.68 ± 0.08a	0.64 ± 0.09ab
Booting	GGA4	0.015^∗	0.000^∗∗∗	0.01^∗∗	0.67 ± 0.08b	0.75 ± 0.07a	0.74 ± 0.09a
Booting	NDVI3	0.033^∗	0.000^∗∗∗	0.16^ns	0.57 ± 0.08b	0.65 ± 0.07a	0.64 ± 0.07a
Anthesis	GGA5	0.000^∗∗∗	0.000^∗∗∗	0.01^∗∗	0.74 ± 0.09b	0.81 ± 0.08a	0.81 ± 0.07a
Anthesis	NDVI4	0.022^∗	0.000^∗∗∗	0.17^ns	0.68 ± 0.07b	0.72 ± 0.04a	0.71 ± 0.05a
Grain filling	GGA6	0.015^∗	0.000^∗∗∗	0.49^ns	0.47 ± 0.15b	0.57 ± 0.17a	0.57 ± 0.16a
Grain filling	NDVI5	0.014^∗	0.000^∗∗∗	0.29^ns	0.58 ± 0.07b	0.63 ± 0.07a	0.64 ± 0.06a
	2018/19
3 leaves	GGA1	0.544^ns	0.000^∗∗∗	0.548^ns	0.02 ± 0.00a	0.02 ± 0.01a	0.01 ± 0.00a
Tillering	GGA2	0.755^ns	0.007^∗∗	0.965^ns	0.19 ± 0.06a	0.20 ± 0.09a	0.17 ± 0.07a
	GGA3	0.924^ns	0.045^∗	1.000^ns	0.46 ± 0.10a	0.47 ± 0.11a	0.44 ± 0.12a
	NDVI1	0.679^ns	0.000^∗∗∗	0.985^ns	0.53 ± 0.09a	0.52 ± 0.10a	0.50 ± 0.11a
Stem elongation	GGA4	0.920^ns	0.002^∗∗	0.987^ns	0.63 ± 0.10a	0.62 ± 0.09a	0.61 ± 0.13a
	GGA5	0.566^ns	0.000^∗∗∗	0.792^ns	0.72 ± 0.08a	0.74 ± 0.07a	0.76 ± 0.09a
	NDVI2	0.808^ns	0.000^∗∗	0.915^ns	0.61 ± 0.07a	0.61 ± 0.07a	0.60 ± 0.08a
	NDVI3	0.821^ns	0.000^∗∗∗	0.668^ns	0.70 ± 0.06a	0.69 ± 0.06a	0.68 ± 0.06a
Booting	GGA6	0.852^ns	0.000^∗∗∗	0.957^ns	0.51 ± 0.12a	0.52 ± 0.12a	0.54 ± 0.10a
Booting	NDVI4	0.997^ns	0.000^∗∗∗	0.822^ns	0.52 ± 0.08a	0.52 ± 0.07a	0.52 ± 0.07a
Heading	GGA7	0.869^ns	0.000^∗∗∗	0.912^ns	0.40 ± 0.12a	0.41 ± 0.11a	0.42 ± 0.10a
Heading	NDVI5	0.986^ns	0.001^∗∗∗	0.968^ns	0.44 ± 0.08a	0.44 ± 0.07a	0.44 ± 0.06a
Anthesis	GGA8	0.685^ns	0.000^∗∗∗	0.840^ns	0.19 ± 0.09a	0.19 ± 0.10a	0.21 ± 0.09a
	GGA9	0.720^ns	0.000^∗∗∗	0.895^ns	0.28 ± 0.27a	0.31 ± 0.28a	0.33 ± 0.26a
	NDVI6	0.676^ns	0.012^∗	0.998^ns	0.33 ± 0.05a	0.32 ± 0.05a	0.32 ± 0.05a
Grain filling	GGA10	0.756^ns	0.000^∗∗∗	0.846^ns	0.23 ± 0.26a	0.25 ± 0.33a	0.22 ± 0.27a

Means of the nitrogen levels followed by different letters are significantly different (p < 0.05) according to Tukey’s honestly significant difference (HSD) test.

^ns

Levels of significance for the ANOVA: ns, not significant;

^∗

p < 0.05;

^∗∗

p < 0.01;

^∗∗∗

p < 0.001.