TABLE 3.

Differences of C accumulation and CHI under different treatments.

Cultivars	Nitrogen rate	Jointing stage (kg ha–1)		Silking stage (kg ha–1)		Maturity stage (kg ha–1)		C harvest index
		2019	2020	2019	2020	2019	2020	2019	2020
	N 0	309.94 de	390.75 e	1711.89 d	2072.86 e	4649.57 e	4279.12 d	0.46 abc	0.43 c
	N 120	335.00 c	433.32 c	2372.74 b	2499.92 c	6241.84 b	5186.75 b	0.47 abc	0.45 b
ZH 311	N 240	412.31 a	504.76 a	2764.71 a	2791.31 a	6980.10 a	5837.16 a	0.45 c	0.44 c
	N 360	385.39 b	414.70 d	2382.82 b	2652.24 b	6435.33 b	5568.12 a	0.46 bc	0.47 ab
	Mean	360.66 A	435.88 A	2308.04 A	2504.08 A	6076.71 A	5217.79 A	0.46 B	0.45 B
	N 0	267.22 f	319.72 f	1557.25 e	1788.95 f	3661.19 f	3314.15 e	0.48 a	0.48 a
	N 120	295.17 e	411.19 d	2113.86 c	2063.92 e	4359.01 e	4017.35 d	0.48 ab	0.47 ab
XY 508	N 240	327.09 cd	452.04 b	2148.36 c	2348.40 d	5147.12 d	4821.77 c	0.48 abc	0.48 a
	N 360	325.66 cd	452.10 b	2290.59 b	2423.10 cd	5601.46 c	4907.12 bc	0.48 ab	0.48 a
	Mean	303.79 B	408.76 B	2027.52 B	2156.09 B	4692.20 B	4265.10 B	0.48 A	0.48 A
F value	Years (Y)	822.43**		70.33**		161.68**		6.35*
	Cultivar (C)	178.69**		263.66**		534.00**		41.15**
	Nitrogen (N)	189.88**		287.27**		249.56**		1.70ns
	Y × C	22.42**		3.04ns		18.23**		0.84ns
	Y × N	11.28**		8.26**		3.62*		1.56ns
	C × N	17.06**		17.82**		13.27**		2.55ns
	Y × C × N	17.03**		4.38*		3.76*		1.43ns

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.