TABLE 5.

Differences of C/N ratios of whole maize plant at different stages.

Cultivars	Nitrogen rate	Jointing stage		Silking stage		Maturity stage		Mean
		2019	2020	2019	2020	2019	2020	2019	2020
	N 0	19.95 b	18.06 b	32.54 b	37.08 b	79.27 b	85.99 b	43.92 b	47.04 b
	N 120	12.35 cd	12.91 c	29.12 d	30.40 c	66.42 d	74.86 d	35.96 d	39.39 d
ZH 311	N 240	11.47 e	11.85 e	20.99 f	24.14 e	59.36 f	61.36 f	30.61 g	32.45 f
	N 360	11.45 e	11.88 e	21.19 f	23.55 e	56.66 g	55.61 g	29.77 g	30.34 g
	Mean	13.80 B	13.67 B	25.96 B	28.79 B	65.43 B	69.46 B	35.06 B	37.31 B
	N 0	21.24 a	18.82 a	38.23 a	42.63 a	86.40 a	90.88 a	48.62 a	50.78 a
	N 120	12.93 c	12.78 c	30.86 c	30.19 c	68.84 c	81.95 c	37.48 c	41.64 c
XY 508	N 240	12.46 cd	11.63 e	23.19 e	25.63 d	62.40 e	64.79 e	32.69 e	34.02 e
	N 360	11.68 de	12.29 d	22.52 e	23.95 e	60.93 e	56.89 g	31.71 f	31.04 g
	Mean	14.58 A	13.88 A	28.70 A	30.60 A	69.59 A	73.63 A	37.62 A	39.37 A
F value	Years (Y)	14.03**		170.23**		174.44**		171.09**
	Cultivar (C)	19.56**		157.63**		186.62**		229.37**
	Nitrogen (N)	1122.20**		1455.49**		1690.94**		2499.91**
	Y × C	6.50*		6.64*		0.00ns		2.66ns
	Y × N	29.27**		22.98**		85.92**		28.55**
	C × N	2.68ns		39.68**		5.75**		18.00**
	Y × C × N	1.71ns		1.08ns		8.43**		2.04ns

Values followed by different lowercase letters are significantly different with p < 0.05; within cultivars, values with different uppercase letters are significantly different with p < 0.05 according to the least significant difference test. **p < 0.01; *p < 0.05; ^nsNot significant. The bold values are the mean value of one cultivar in different N treatments.