Determining optimal mulching, planting density, and nitrogen application to increase maize grain yield and nitrogen translocation efficiency in Northwest China

Table 2 Maize cob length, cob number, kernel number per cob, and thousand kernel weight as affected by mulch, nitrogen fertilizer application rate, and planting density (D_L: 55,000 seeds ha^− 1; D_H: 90,000 seeds ha^− 1) in 2015, 2016, and 2017

Year	Mulch	Nitrogen	Cob length (cm)		Cob number (ha^− 1)		Kernel number per cob		Thousand kernel weight (g)
Year	Mulch	Nitrogen	D_L	D_H	D_L	D_H	D_L	D_H	D_L	D_H
2015	No	N₀	14.6	15.3	42,997	77,757	470	385	223	149
		N₁₂₀	16.6	16.3	48,703	79,281	555	437	276	211
		N₂₄₀	17.3	16.5	48,894	79,500	571	469	315	222
		N₃₆₀	17.2	16.5	49,023	79,953	581	465	299	240
	Yes	N₀	15.3	14.3	45,143	76,345	473	418	214	155
		N₁₂₀	17.2	16.8	48,642	79,087	583	461	253	248
		N₂₄₀	17.6	16.9	49,284	81,562	617	485	271	255
		N₃₆₀	17.5	16.8	49,112	81,349	613	497	276	265
2016	No	N₀	15.4	15.6	45,114	77,496	484	395	234	157
		N₁₂₀	17.0	16.5	48,892	80,244	563	447	290	221
		N₂₄₀	17.6	16.8	49,151	79,772	579	482	330	233
		N₃₆₀	17.4	16.6	48,679	80,270	583	469	301	252
	Yes	N₀	15.9	15.4	45,304	77,291	478	444	225	163
		N₁₂₀	18.0	17.1	49,151	80,691	582	459	266	261
		N₂₄₀	18.1	17.2	49,705	82,303	613	509	285	268
		N₃₆₀	17.8	17.2	50,029	82,422	594	495	289	278
2017	No	N₀	16.0	15.7	44,857	78,187	492	398	246	165
		N₁₂₀	16.9	16.7	49,651	81,211	553	448	305	232
		N₂₄₀	17.6	16.6	49,105	79,865	576	484	347	245
		N₃₆₀	17.4	16.5	49,166	79,301	591	494	335	264
	Yes	N₀	15.4	15.2	45,633	76,469	484	447	236	171
		N₁₂₀	18.0	16.9	49,764	80,041	590	468	279	274
		N₂₄₀	17.7	17.0	49,960	81,762	615	501	299	281
		N₃₆₀	18.1	16.9	49,391	81,838	622	525	302	292
Treatment effect (P values) ^a
Year (Y)			< 0.001		ns		0.008		< 0.001
Mulch (M)			< 0.001		ns		< 0.001		< 0.001
Nitrogen (N)			< 0.001		< 0.001		< 0.001		< 0.001
Density (D)			< 0.001		< 0.001		< 0.001		< 0.001
Y * M			ns		ns		ns		ns
Y * N			ns		ns		ns		ns
Y * D			ns		ns		ns		ns
M * N			0.01		ns		ns		< 0.001
M * D			ns		ns		ns		ns
N * D			ns		ns		< 0.001		< 0.001
Y * M * N			ns		ns		ns		ns
Y * M * D			ns		ns		ns		ns
Y * N * D			ns		ns		ns		ns
M * N * D			ns		ns		0.006		ns
Y * M * N * D			ns		ns		ns		ns

ISSN: 1471-2229