Effects of changes in applied nitrogen concentrations on nodulation, nitrogen fixation and nitrogen accumulation during the soybean growth period

Figures & data

Figure 1. Double-root soybean material

Table 1. Nitrogen application concentrations (mg l⁻¹) in this study

Groups	Treaments	Test I (VC-V4)	Test II (V4-R1)	Test III (R1-R2)
First group	NTTT	25	25	25
	NTHH	25	100	100
	NTHT	25	100	25
Second group	NHHH	100	100	100
	NHTT	100	25	25
	NHTH	100	25	100

Table 2. Changes in the number and weight of root nodules of soybean plants inVC-V4, V4-R1, R1-R2 growth periods of soybean

				Test Ⅰ0 (VC-V4)		Test Ⅱ (V4-R1)		Test Ⅲ (R1-R2)
		Treaments	nitrogen concentration changes (mg l^−1)	N+	N-	N+	N-	N+	N-
Nodules number (per plant)	2017	NTTT	25-25-25	68.7 ± 10.59a	59.0 ± 5.2a	112.0 ± 8.03a	194.0 ± 47.59a	156.0 ± 21.21a*	318.5 ± 62.28a
		NTHH	25-100-100			114.3 ± 17.52a	158.8 ± 22.6ab	122.8 ± 11.56ab	191.8 ± 11.43b
		NTHT	25-100-25					157.5 ± 22.21a	207.8 ± 36.05b
		NHHH	100-100-100	43.3 ± 6.73a	63.2 ± 9.6a	85.5 ± 8.53ab*	225.0 ± 34.31a	98.8 ± 31.53ab*	248.5 ± 45.06b
		NHTT	100-25-25			61.0 ± 3.19b	134.2 ± 29.75b	98.0 ± 18.64ab**	277.0 ± 34.3ab
		NHTH	100-25-100					75.0 ± 30.19b**	328.8 ± 32.52a
	2018	NTTT	25-25-25	122.7 ± 14.19a	95.7 ± 8.97a	116.1 ± 7.31ab	125.6 ± 12.44a	406.0 ± 37.50ab	384.3 ± 22.98ab
		NTHH	25-100-100			140.7 ± 18.72a	118.4 ± 11.01a	327.3 ± 13.81b	325.3 ± 14.81b
		NTHT	25-100-25					449.0 ± 15.44a*	274.3 ± 35.41b
		NHHH	100-100-100	94.0 ± 17.08a	103.7 ± 13.81a	109.4 ± 11.42b*	132.1 ± 13.14a	324.0 ± 24.14b	369.3 ± 57.18b
		NHTT	100-25-25			105.9 ± 4.51b	131.0 ± 14.31a	521.3 ± 22.35a*	410.4 ± 58.71a
		NHTH	100-25-100					262.0 ± 29.50b*	340.1 ± 17.51b
Nodules weight (g plant^−1)	2017	NTTT	25-25-25	0.14 ± 0.027a	0.14 ± 0.014a	0.35 ± 0.034a	0.60 ± 0.071a	0.69 ± 0.131a*	1.21 ± 0.091a
		NTHH	25-100-100			0.31 ± 0.021a	0.40 ± 0.022b	0.45 ± 0.062b	0.68 ± 0.104b
		NTHT	25-100-25					0.43 ± 0.054b	0.89 ± 0.182b
		NHHH	100-100-100	0.04 ± 0.01b*	0.14 ± 0.091a	0.12 ± 0.011b**	0.45 ± 0.063b	0.23 ± 0.031c*	0.86 ± 0.151b
		NHTT	100-25-25			0.13 ± 0.013b*	0.34 ± 0.081b	0.42 ± 0.114b*	1.05 ± 0.052a
		NHTH	100-25-100					0.24 ± 0.102c*	1.17 ± 0.194a
	2018	NTTT	25-25-25	0.16 ± 0.01a	0.15 ± 0.01a	0.46 ± 0.02a	0.49 ± 0.04a	0.70 ± 0.09a	0.78 ± 0.10a
		NTHH	25-100-100			0.38 ± 0.02b	0.42 ± 0.06a	0.51 ± 0.11b	0.47 ± 0.06b
		NTHT	25-100-25					0.72 ± 0.06a*	0.48 ± 0.05b
		NHHH	100-100-100	0.08 ± 0.02b	0.16 ± 0.01a	0.28 ± 0.04c**	0.48 ± 0.03a	0.52 ± 0.09b*	0.75 ± 0.09a
		NHTT	100-25-25			0.40 ± 0.03b	0.48 ± 0.07a	0.79 ± 0.12a	0.82 ± 0.21a
		NHTH	100-25-100					0.49 ± 0.06b*	0.73 ± 0.04a

Values represent mean±SE (n = 4). Different small letters mean significant differences among treatment at the 0.05 levels, respectively, vertical comparison. * and ** represent the comparison between the nitrogen application side (N+) and the non-nitrogen application side (N-); *Indicates a significant level of 5%; **indicates a significant level of 1%.

Table 3. Changes in specific nitrogenase activity per gram dry weigh and acetylene reduction activity per hour in the soybean root nodules in VC-V4, V4-R1, R1-R2 growth periods of soybean

				Test Ⅰ (VC-V4)		Test Ⅱ (V4-R1)		Test Ⅲ (R1-R2)
		Treaments	nitrogen concentration changes (mg l^−1)	N+	N-	N+	N-	N+	N-
SNA (C2H4 μmol g^−1 nodule dry mass h^−1).	2017	NTTT	25-25-25	76.7 ± 3.25a	78.1 ± 3.66a	47.7 ± 3.43b	53.5 ± 2.36b	80.2 ± 9.99b	82.5 ± 9.45b
		NTHH	25-100-100			24.5 ± 2.58c	29.4 ± 4.15c	76.7 ± 5.88b	82.5 ± 7.31b
		NTHT	25-100-25					107.9 ± 5.21a	110.6 ± 6.46a
		NHHH	100-100-100	38.4 ± 3.97b**	70.9 ± 8.42a	51.7 ± 4.14b	58.4 ± 1.78b	93.6 ± 12.39ab	109.7 ± 14.76a
		NHTT	100-25-25			61.1 ± 2.49a	71.8 ± 1.20a	110.1 ± 17.08a	99.9 ± 11.77a
		NHTH	100-25-100					93.2 ± 9.41ab	103.9 ± 7.67a
	2018	NTTT	25-25-25	44.6 ± 3.35a	47.5 ± 2.14a	59.6 ± 3.61b	58 ± 3.84b	66.3 ± 4.68ab	63.4 ± 1.87a
		NTHH	25-100-100			47.4 ± 1.87c	46 ± 2.72c	59.4 ± 4.19b	58.3 ± 2.05b
		NTHT	25-100-25					71.3 ± 3.57a	75.9 ± 2.14a
		NHHH	100-100-100	38.7 ± 1.25b	43.7 ± 2.45a	62.4 ± 4.77b	63.9 ± 3.92b	56.0 ± 5.58b	57.1 ± 3.79a
		NHTT	100-25-25			70.3 ± 3.88a	65.6 ± 2.14a	70.1 ± 1.69a	72.4 ± 0.27a
		NHTH	100-25-100					52.0 ± 6.20b	67.9 ± 1.16a
ARA（C2H4 μmol h^−1 plant^−1)	2017	NTTT	25-25-25	10.2 ± 0.98a	10.7 ± 0.17a	16.5 ± 0.53a*	31.6 ± 2.49a	60.2 ± 13.78a*	102.1 ± 15.20a
		NTHH	25-100-100			7.1 ± 0.627b	11.6 ± 1.33b	35.2 ± 4.37b	57.5 ± 10.08b
		NTHT	25-100-25					46.3 ± 3.79ab*	101.6 ± 15.87a
		NHHH	100-100-100	1.3 ± 0.05b**	10.2 ± 1.96a	6.2 ± 0.89b**	26.7 ± 3.07a	20.9 ± 2.89b**	99.9 ± 20.33a
		NHTT	100-25-25			7.5 ± 0.26b**	24.0 ± 3.56a	61.5 ± 17.34a*	105.7 ± 13.73a
		NHTH	100-25-100					18.7 ± 4.19b**	127.5 ± 22.21a
	2018	NTTT	25-25-25	3.6 ± 0.27a	3.0 ± 0.09a	15.2 ± 0.89a	16.9 ± 0.98a	30.7 ± 4.64a*	77.6 ± 0.67a
		NTHH	25-100-100			10.0 ± 0.58b	10.5 ± 1.47b	14.2 ± 1.83b*	44.8 ± 2.32b
		NTHT	25-100-25					31.6 ± 1.83a*	79.4 ± 1.16a
		NHHH	100-100-100	1.5 ± 0.36b	3.6 ± 0.22a	10.5 ± 1.65b	14.5 ± 1.12b	16.7 ± 1.74b*	47.5 ± 2.41b
		NHTT	100-25-25			14.5 ± 1.56a	15.2 ± 1.69b	30.2 ± 1.69a*	66.1 ± 1.83a
		NHTH	100-25-100					14.9 ± 1.34b**	69.7 ± 1.74a

Values represent mean±SE (n = 4). Different small letters mean significant differences among treatment at the 0.05 levels, respectively, vertical comparison. * and ** represent the comparison between the nitrogen application side (N+) and the non-nitrogen application side (N-); *Indicates a significant level of 5%; **indicates a significant level of 1%.

Table 4. Changes in the nitrogen content and C/N ratio of soybean shoots in VC-V4, V4-R1, R1-R2 growth periods of soybean

			Test Ⅰ (VC-V4)		Test Ⅱ (V4-R1)		Test Ⅲ (R1-R2)
	Treatments	nitrogen concentration changes (mg l^−1)	N (g kg^−1)	C/N	N (g kg^−1)	C/N	N (g kg^−1)	C/N
2017	NTTT	25-25-25	54.8 ± 1.46b	8.26 ± 0.32a	51.7 ± 1.44b	9.4 ± 0.07a	48.9 ± 1.13b	9.2 ± 0.02a
	NTHH	25-100-100			68.0 ± 0.87a	6.6 ± 0.00b	56.1 ± 1.34a	7.6 ± 0.45b
	NTHT	25-100-25					51.9 ± 1.95ab	8.5 ± 0.08ab
	NHHH	100-100-100	73.1 ± 1.32a	6.51 ± 0.08a	69.3 ± 1.13a	6.4 ± 0.01b	58.8 ± 0.93a	7.4 ± 0.02b
	NHTT	100-25-25			52.5 ± 1.67b	8.8 ± 0.01a	49.0 ± 0.07b	9.0 ± 0.05a
	NHTH	100-25-100					53.0 ± 0.98ab	7.6 ± 0.03b
2018	NTTT	25-25-25	39.0 ± 1.47b	8.5 ± 0.36a	51.5 ± 0.31b	9.4 ± 0.31a	45.1 ± 2.10b	9.3 ± 0.33a
	NTHH	25-100-100			66.9 ± 1.24a	6.7 ± 0.03b	55.5 ± 1.93ab	7.1 ± 0.32b
	NTHT	25-100-25					49.6 ± 0.91b	7.9 ± 0.37b
	NHHH	100-100-100	47.5 ± 0.63a	6.3 ± 0.18a	73.3 ± 1.19a	6.2 ± 0.37b	64.7 ± 2.21a	6.0 ± 0.37b
	NHTT	100-25-25			54.1 ± 1.59b	8.9 ± 0.01a	46.9 ± 1.11b	9.2 ± 0.12a
	NHTH	100-25-100					54.5 ± 1.78ab	7.3 ± 0.17b

Values represent mean±SE (n = 4). Different small letters mean significant differences among treatment at the 0.05 levels, respectively, vertical comparison.

Table 5. Changes in the nitrogen content and C/N ratio of soybean roots in VC-V4, V4-R1, R1-R2 growth periods of soybean

				Test Ⅰ (VC-V4)		Test Ⅱ (V4-R1)		Test Ⅲ (R1-R2)
		Treatments	Nitrogen concentration changes (mg l^−1)	N+	N-	N+	N-	N+	N-
Nitrogen content （g kg^−1)	2017	NTTT	25-25-25	14.2 ± 1.39b	14.3 ± 1.16a	15.2 ± 0.35b	13.3 ± 0.86a	16.7 ± 1.69b	15.0 ± 0.67a
		NTHH	25-100-100			21.3 ± 1.19a**	14.0 ± 0.79a	22.2 ± 0.58a	19.6 ± 1.54a
		NTHT	25-100-25					16.1 ± 1.61b	16.8 ± 0.65a
		NHHH	100-100-100	21.0 ± 0.70a*	17.3 ± 0.53a	22.9 ± 1.22a**	16.0 ± 0.86a	22.9 ± 0.44a*	18.8 ± 0.14a
		NHTT	100-25-25			19.07 ± 1.06b	17.4 ± 2.06a	15.5 ± 1.25b	11.2 ± 1.03b
		NHTH	100-25-100					18.1 ± 0.55b	16.0 ± 1.15a
	2018	NTTT	25-25-25	16.1 ± 0.45b	16.0 ± 1.12a	13.9 ± 0.89b	12.0 ± 0.85a	16.6 ± 0.41b	14.2 ± 0.35b
		NTHH	25-100-100			16.3 ± 0.33ab	14.9 ± 0.50a	20.8 ± 0.21a	19.9 ± 0.50a
		NTHT	25-100-25					16.3 ± 1.55b	18.0 ± 0.44a
		NHHH	100-100-100	20.9 ± 0.36a*	15.±0.92a	18.2 ± 0.63a*	13.0 ± 0.29a	22.5 ± 2.45a*	16.3 ± 0.20ab
		NHTT	100-25-25			14.6 ± 0.33ab	12.6 ± 0.80a	16.2 ± 0.39b	12.0 ± 0.48b
		NHTH	100-25-100					19.0 ± 0.17ab	16.8 ± 0.75ab
C/N	2017	NTTT	25-25-25	27.5 ± 3.12a	29.5 ± 3.01a	26.6 ± 1.65a	29.9 ± 2.19a	27.4 ± 1.87a	30.9 ± 3.02a
		NTHH	25-100-100			19.9 ± 0.90b*	28.9 ± 1.76a	19.9 ± 0.86b	23.2 ± 1.00b
		NTHT	25-100-25					27.8 ± 1.78a	27.4 ± 1.42a
		NHHH	100-100-100	18.8 ± 1.08b	22.2 ± 1.40b	18.0 ± 0.97b**	27.6 ± 1.98a	19.1 ± 0.76b**	27.4 ± 0.62a
		NHTT	100-25-25			24.8 ± 1.12a	26.5 ± 0.92a	28.2 ± 2.72a*	33.0 ± 3.28a
		NHTH	100-25-100					25.9 ± 1.00a*	30.2 ± 2.19a
	2018	NTTT	25-25-25	26.3 ± 0.47a	28.0 ± 0.60 a	27.4 ± 0.45a	29.8 ± 0.42a	28.3 ± 0.17a	30.1 ± 1.03a
		NTHH	25-100-100			18.2 ± 0.38b**	28.3 ± 0.21a	19.9 ± 0.04b	22.3 ± 0.77b
		NTHT	25-100-25					27.9 ± 0.50a	28.2 ± 0.55a
		NHHH	100-100-100	15.6 ± 0.61b*	22.8 ± 0.54b	17.4 ± 0.85b**	26.2 ± 0.97a	18.3 ± 0.52b*	23.1 ± 0.46b
		NHTT	100-25-25			23.0 ± 0.54a	26.5 ± 0.51a	26.7 ± 0.35a*	31.4 ± 1.74a
		NHTH	100-25-100					25.3 ± 0.86a*	29.3 ± 0.48a

Values represent mean±SE (n = 4). Different small letters mean significant differences among treatment at the 0.05 levels, respectively, vertical comparison. * and ** represent the comparison between the nitrogen application side (N+) and the non-nitrogen application side (N-); *Indicates a significant level of 5%; **indicates a significant level of 1%.

Table 6. Changes in the dry weight and nitrogen accumulation of soybean shoots in VC-V4, V4-R1, R1-R2 growth periods of soybean

			Test Ⅰ (VC-V4)		Test Ⅱ (V4-R1)		Test Ⅲ (R1-R2)
	Treatments	nitrogen concentration changes (mg l^−1)	DW (g plant^−1)	NA (mg plant^−1)	DW (g plant^−1)	NA (mg plant^−1)	DW(g plant^−1)	NA (mg plant^−1)
2017	NTTT	25-25-25	2.07 ± 0.829a	67.7 ± 2.35b	9.15 ± 0.339b	281.5 ± 6.75c	22.03 ± 1.442b	664.3 ± 48.86b
	NTHH	25-100-100			8.97 ± 0.474b	332.7 ± 9.28b	23.06 ± 2.029ab	730.0 ± 46.19b
	NTHT	25-100-25					23.27 ± 2.359ab	693.5 ± 94.14b
	NHHH	100-100-100	3.75 ± 0.137a	142.4 ± 4.62a	13.54 ± 0.512a	523.7 ± 22.01a	28.98 ± 3.037a	1068.3 ± 87.70a
	NHTT	100-25-25			9.95 ± 0.490b	303.1 ± 18.66b	23.39 ± 1.122ab	699.4 ± 36.01b
	NHTH	100-25-100					26.68 ± 1.716ab	814.7 ± 42.90b
2018	NTTT	25-25-25	1.51 ± 0.214b	58.9 ± 2.39b	5.30 ± 0.50b	272.9 ± 9.21c	10.07 ± 0.33b	454.2 ± 43.23b
	NTHH	25-100-100			6.06 ± 0.20b	405.4 ± 14.39b	11.73 ± 0.55b	651.0 ± 38.92b
	NTHT	25-100-25					12.92 ± 0.46ab	640.8 ± 54.61b
	NHHH	100-100-100	2.13 ± 0.123a	101.2 ± 14.32a	7.88 ± 0.58a	577.6 ± 21.21a	15.04 ± 0.27a	973.1 ± 71.82a
	NHTT	100-25-25			6.61 ± 0.68ab	357.6 ± 11.31b	10.98 ± 0.89b	515.0 ± 39.91b
	NHTH	100-25-100					11.15 ± 1.22b	607.7 ± 51.21b

Values represent mean±SE (n = 4). Different small letters mean significant differences among treatment at the 0.05 levels, respectively, vertical comparison.

Table 7. Changes in the dry weight and nitrogen accumulation of soybean roots in VC-V4, V4-R1, R1-R2 growth periods of soybean

				Test Ⅰ (VC-V4)		Test Ⅱ (V4-R1)		Test Ⅲ (R1-R2)
		Treatments	Nitrogen concentration changes (mg l^−1)	N+	N-	N+	N-	N+	N-
Dry weight（g plant^−1)	2017	NTTT	25-25-25	0.68 ± 0.034b	0.58 ± 0.036a	1.17 ± 0.096d	1.33 ± 0.422a	2.49 ± 0.028b	2.44 ± 0.221a
		NTHH	25-100-100			1.50 ± 0.026c	1.15 ± 0.118a	2.75 ± 0.352ab	2.09 ± 0.346a
		NTHT	25-100-25					2.32 ± 0.021b	2.41 ± 0.463a
		NHHH	100-100-100	1.24 ± 0.364a	0.74 ± 0.172a	2.39 ± 0.186a	1.53 ± 0.229a	3.89 ± 0.324a*	2.59 ± 0.383a
		NHTT	100-25-25			1.94 ± 0.234b	1.25 ± 0.073a	3.17 ± 0.237ab	2.27 ± 0.127a
		NHTH	100-25-100					3.18 ± 0.345ab	2.17 ± 0.084a
	2018	NTTT	25-25-25	0.72 ± 0.051a	0.60 ± 0.011a	0.70 ± 0.071b	0.66 ± 0.03b	3.18 ± 0.38c	1.96 ± 0.12c
		NTHH	25-100-100			0.91 ± 0.06b	0.58 ± 0.10b	4.41 ± 0.02b	3.00 ± 0.53b
		NTHT	25-100-25					4.16 ± 0.10b*	2.16 ± 0.24c
		NHHH	100-100-100	0.84 ± 0.112a	0.81 ± 0.062a	1.24 ± 0.16a	0.90 ± 0.04a	5.20 ± 0.66a	4.37 ± 0.65a
		NHTT	100-25-25			1.22 ± 0.09a	0.97 ± 0.10a	3.81 ± 0.34c	3.38 ± 0.17b
		NHTH	100-25-100					3.78 ± 0.22c	3.68 ± 0.35b
Nitrogen accumulation （mg plant^−1)	2017	NTTT	25-25-25	5.2 ± 0.48b	3.8 ± 0.45b	17.7 ± 1.43c	13.8 ± 0.23b	41.6 ± 0.02c	36.8 ± 0.65b
		NTHH	25-100-100			32.0 ± 3.00b**	16.6 ± 0.84b	63.0 ± 6.00b	47.0 ± 7.26a
		NTHT	25-100-25					36.0 ± 4.10c	42.5 ± 8.78a
		NHHH	100-100-100	24.1 ± 2.80a	14.6 ± 2.35a	55.8 ± 6.75a**	21.6 ± 2.19a	97.5 ± 8.75a**	44.6 ± 6.73a
		NHTT	100-25-25			39.9 ± 2.17b**	20.8 ± 2.17a	48.6 ± 6.00c**	24.9 ± 2.05c
		NHTH	100-25-100					57.6 ± 4.60bc**	34.6 ± 3.22b
	2018	NTTT	25-25-25	7.5 ± 0.22b	5.6 ± 0.61b	9.7 ± 1.06b	7.9 ± 4.03b	52.8 ± 3.16c	27.8 ± 0.04c
		NTHH	25-100-100			14.8 ± 1.02ab	8.6 ± 1.05b	91.7 ± 5.39b	59.7 ± 0.27b
		NTHT	25-100-25					67.8 ± 4.16c	38.9 ± 0.11c
		NHHH	100-100-100	17.6 ± 0.04a	12.2 ± 0.06a	22.6 ± 4.10a	11.7 ± 3.01a	117.0 ± 7.62a	71.2 ± 0.13a
		NHTT	100-25-25			17.8 ± 3.03ab	12.2 ± 2.08a	61.7 ± 6.13c	40.6 ± 0.08c
		NHTH	100-25-100					71.8 ± 3.04c	61.8 ± 0.26b

Values represent mean±SE (n = 4). Different small letters mean significant differences among treatment at the 0.05 levels, respectively, vertical comparison. * and ** represent the comparison between the nitrogen application side (N+) and the non-nitrogen application side (N-); *Indicates a significant level of 5%; **indicates a significant level of 1%.