Table 1.

Dry weight of grain and straw, Zn and N concentrations of grain and straw, and grain Zn (ZnHI) and N (NHI) harvest index of summer maize as affected by N application rates in 2009 and 2010, respectively, in the field.

Year	N treatment	Dry weight (g plant–1)		Zn concentration (mg kg-1)		N concentration (%)
		Grain	Straw	Grain	Straw	Grain	Straw	ZnHI	NHI
2009	N0	88.3b	82.3b	14.9c	15.2b	1.2b	0.6b	51.9a	69.5a
	N1	131.3a	118.3a	17.1b	21.6a	1.4a	0.7a	46.8a	67.9a
	N2	127.9a	112.6a	18.5a	24.8a	1.3ab	0.8a	46.3a	64.5a
2010	N0	84.3b	74.3b	15.2b	20.3a	1.2b	0.6b	45.8a	67.1a
	N1	120.3a	118.4a	18.8a	25.0a	1.4a	0.8a	43.7a	63.5a
	N2	122.1a	122.0a	19.3a	25.3a	1.5a	0.9a	43.9a	62.6a
Source of variation
N treatment (N)		***	***	***	*	***	***	ns	ns
Year (Y)		ns	ns	*	ns	ns	*	ns	ns
N*Y		ns	ns	ns	ns	ns	ns	ns	ns

Values followed by different lowercase letters in columns represent significant differences among the different N application rates.

ns indicates no significant difference. *, and *** indicate significant difference at P < 0.05, and < 0.001, respectively.