Table 1 Effects of different irrigation methods and nitrogen application rates on grain yields and its components of summer maize.
Year
|
Irrigation method
|
Nitrogen application rate
(kg ha−1)
|
Harvest ear
(No. ha−1)
|
Kernels per ear
(No. ear−1)
|
1000-grain weight
(g)
|
Grain yield
(kg ha−1)
|
2017
|
DI
|
N0
|
67407.4a
|
497.2de
|
359.6e
|
9036.5d
|
|
|
N162
|
68888.9a
|
516.7c
|
371.4cd
|
11699.9b
|
|
|
N216
|
67777.8a
|
528.9ab
|
378.7ab
|
12316.7a
|
|
|
N270
|
68518.5a
|
530.6a
|
381.0a
|
12577.5a
|
|
SI
|
N0
|
66296.3a
|
496.1de
|
357.3e
|
8799.3de
|
|
|
N162
|
68888.9a
|
516.2c
|
373.8bcd
|
11414.0bc
|
|
|
N216
|
69629.6a
|
521.8abc
|
378.2abc
|
12208.1a
|
|
|
N270
|
69259.3a
|
527.2abc
|
380.1ab
|
12301.6a
|
|
FI
|
N0
|
67407.4a
|
490.2e
|
356.5e
|
8554.7e
|
|
|
N162
|
68888.9a
|
504.7d
|
367.7d
|
10985.3c
|
|
|
N216
|
68888.9a
|
518.8bc
|
373.7bcd
|
11467.5b
|
|
|
N270
|
68888.9a
|
522.1abc
|
378.8ab
|
12160.7a
|
2018
|
DI
|
N0
|
65185.2ab
|
466.7f
|
340.0b
|
8756.9d
|
|
|
N162
|
66666.7a
|
493.9def
|
359.1a
|
10167.5b
|
|
|
N216
|
64814.8ab
|
536.7ab
|
366.9a
|
11166.1a
|
|
|
N270
|
65185.2ab
|
550.1a
|
368.2a
|
11529.5a
|
|
SI
|
N0
|
64074.1ab
|
504.2cde
|
334.6b
|
9319.3c
|
|
|
N162
|
64444.4ab
|
519.4bcd
|
361.0a
|
10370.0b
|
|
|
N216
|
65185.2ab
|
543.1ab
|
366.5a
|
11091.7a
|
|
|
N270
|
64074.0ab
|
548.4a
|
368.2a
|
11495.7a
|
|
FI
|
N0
|
62962.9b
|
479.1ef
|
338.7b
|
8170.6e
|
|
|
N162
|
63333.3b
|
502.2de
|
358.3a
|
9091.8cd
|
|
|
N216
|
63703.7b
|
518.7bcd
|
362.3a
|
10575.6b
|
|
|
N270
|
64814.8ab
|
531.3abc
|
364.4a
|
11340.7a
|
ANOVA
|
|
|
|
|
I
|
0.421
|
0.002
|
0.111
|
<0.001
|
N
|
0.029
|
<0.001
|
<0.001
|
<0.001
|
I × N
|
0.546
|
0.070
|
0.434
|
0.286
|
Note: Different letters in a row are significant differences among treatments in each year (P<0.05). I: Irrigation methods, N: N application rates. DI: drip irrigation, SI: micro-sprinkler irrigation, FI: flooding irrigation. N0: 0 kg N ha-1, N162: 162 kg N ha-1, N216: 216 kg N ha-1, N270: 270 kg N ha-1.
Table 2 Effects of different irrigation methods and nitrogen application rates of accumulation amounts and distribution of dry matter in pre-anthesis and post-anthesis stages of summer maize.
Year
|
Irrigation
method
|
Nitrogen application rate
(kg ha−1)
|
Biomass of R6
(t ha−1)
|
Pre-anthesis
(t ha−1)
|
Post-anthesis
(t ha−1)
|
Percentage of pre-anthesis (%)
|
Percentage of post-anthesis (%)
|
2017
|
DI
|
N0
|
17.43 f
|
6.30 b
|
11.12 e
|
36.17
|
63.83
|
|
|
N162
|
20.60 d
|
6.83 a
|
13.78 c
|
33.17
|
66.83
|
|
|
N216
|
22.13 b
|
7.03 a
|
15.10 ab
|
31.78
|
68.22
|
|
|
N270
|
22.85 a
|
7.29 a
|
15.56 a
|
31.9
|
68.10
|
|
SI
|
N0
|
16.67 g
|
6.07 b
|
10.61 e
|
36.36
|
63.64
|
|
|
N162
|
20.90 cd
|
6.88 a
|
14.03 bc
|
32.96
|
67.04
|
|
|
N216
|
22.46 ab
|
6.98 a
|
15.48 a
|
31.1
|
68.90
|
|
|
N270
|
22.74 ab
|
7.01 a
|
15.74 a
|
30.8
|
69.20
|
|
FI
|
N0
|
16.38 g
|
6.27 b
|
10.12 e
|
38.26
|
61.74
|
|
|
N162
|
19.75 e
|
7.23 a
|
12.54 d
|
36.53
|
63.47
|
|
|
N216
|
20.66 d
|
7.16 a
|
13.50 cd
|
34.69
|
65.31
|
|
|
N270
|
21.38 c
|
7.30 a
|
14.07 bc
|
34.15
|
65.85
|
2018
|
DI
|
N0
|
15.27 f
|
5.70 e
|
9.57 f
|
37.39
|
62.61
|
|
|
N162
|
20.19 bc
|
7.44 ab
|
12.75 cd
|
36.85
|
63.15
|
|
|
N216
|
21.19 ab
|
7.53 ab
|
13.66 ab
|
35.59
|
64.41
|
|
|
N270
|
21.86 a
|
7.77 a
|
14.09 a
|
35.55
|
64.45
|
|
SI
|
N0
|
14.57 f
|
5.53 e
|
9.03 f
|
37.94
|
62.06
|
|
|
N162
|
18.11 e
|
6.86 cd
|
11.25 e
|
37.86
|
62.14
|
|
|
N216
|
19.73 cd
|
7.12 bc
|
12.60 cd
|
36.1
|
63.90
|
|
|
N270
|
20.28 bc
|
7.29 abc
|
12.99 bc
|
35.93
|
64.07
|
|
FI
|
N0
|
12.86 g
|
4.92 f
|
7.94 g
|
38.3
|
61.70
|
|
|
N162
|
17.83 e
|
6.56 d
|
11.27 e
|
36.8
|
63.20
|
|
|
N216
|
18.80 de
|
6.85 cd
|
11.95 de
|
36.45
|
63.55
|
|
|
N270
|
19.76 cd
|
7.22 bc
|
12.55 cd
|
36.53
|
63.47
|
Note: Different letters in a row are significant differences among treatments in each year (P<0.05). DI: drip irrigation, SI: micro-sprinkler irrigation, FI: flooding irrigation. N0: 0 kg N ha-1, N162: 162 kg N ha-1, N216: 216 kg N ha-1, N270: 270 kg N ha-1. R6: physiological maturity.
Table 3 Effects of different irrigation methods and nitrogen application rates on nitrogen accumulation and distribution in summer maize.
Year
|
Irrigation method
|
Nitrogen application rate (kg ha−1)
|
Nitrogen accumulation amount of VT (kg ha−1)
|
|
Nitrogen accumulation amount of R6 (kg ha−1)
|
Stem
|
Leaf
|
Plant
|
|
Stem
|
Leaf
|
Grain
|
Plant
|
2017
|
DI
|
N0
|
39.94 f
|
59.89 fgh
|
99.83 e
|
|
21.80 g
|
28.85 e
|
101.44 g
|
152.09 g
|
|
|
N162
|
51.20 cde
|
64.33 def
|
115.53 cd
|
|
29.84 e
|
40.42 cd
|
142.70 e
|
212.96 e
|
|
|
N216
|
54.72 abcd
|
66.65 cde
|
121.37 abc
|
|
33.98 bcd
|
43.17 bc
|
170.39 ab
|
247.54 b
|
|
|
N270
|
56.28 ab
|
72.32 ab
|
128.60 a
|
|
37.97 a
|
44.82 ab
|
175.53 a
|
258.31 a
|
|
SI
|
N0
|
41.51 f
|
58.01 gh
|
99.52 e
|
|
22.45 fg
|
29.04 e
|
98.73 g
|
150.22 g
|
|
|
N162
|
51.53 bcde
|
64.92 def
|
116.44 bcd
|
|
31.82 de
|
38.68 d
|
144.45 de
|
214.95 de
|
|
|
N216
|
55.35 abc
|
66.94 bcde
|
122.29 abc
|
|
32.82 cd
|
45.18 ab
|
161.96 c
|
239.96 c
|
|
|
N270
|
57.58 a
|
68.82 abcd
|
126.40 a
|
|
36.57 ab
|
47.40 a
|
164.30 bc
|
248.27 b
|
|
FI
|
N0
|
38.54 f
|
56.26 h
|
94.80 e
|
|
24.54 f
|
27.21 e
|
96.38 g
|
148.13 g
|
|
|
N162
|
47.70 e
|
62.82 efg
|
110.52 d
|
|
33.56 cd
|
39.20 d
|
128.01 f
|
200.77 f
|
|
|
N216
|
50.39 de
|
71.03 abc
|
121.42 abc
|
|
35.15 bc
|
40.58 cd
|
145.90 de
|
221.62 d
|
|
|
N270
|
51.51 bcde
|
73.68 a
|
125.18 ab
|
|
38.97 a
|
45.04 ab
|
150.12 d
|
234.14 c
|
2018
|
DI
|
N0
|
27.89 e
|
46.11 e
|
74.00 e
|
|
16.86 g
|
20.91 c
|
76.96 e
|
114.73 f
|
|
|
N162
|
46.20 cd
|
58.29 cd
|
104.48 cd
|
|
24.68 ef
|
30.63 b
|
129.60 bc
|
184.91 d
|
|
|
N216
|
46.38 cd
|
64.78 abc
|
111.15 abc
|
|
26.43 de
|
35.92 a
|
158.87 a
|
221.22 ab
|
|
|
N270
|
49.12 bc
|
67.42 ab
|
116.54 a
|
|
29.79 ab
|
38.20 a
|
160.00 a
|
227.99 a
|
|
SI
|
N0
|
25.26 ef
|
40.91 ef
|
66.17 ef
|
|
16.54 g
|
17.32 d
|
78.15 e
|
112.01 f
|
|
|
N162
|
43.98 d
|
54.92 d
|
98.90 d
|
|
22.38 f
|
32.37 b
|
131.55 bc
|
186.30 d
|
|
|
N216
|
51.21 ab
|
61.13 bcd
|
112.34 abc
|
|
24.92 de
|
36.00 a
|
151.58 a
|
212.51 bc
|
|
|
N270
|
54.09 a
|
61.12 bcd
|
115.21 ab
|
|
27.25 cd
|
37.92 a
|
157.15 a
|
222.31 ab
|
|
FI
|
N0
|
24.27 f
|
37.61 f
|
61.88 f
|
|
15.97 g
|
18.83 cd
|
68.67 e
|
103.48 f
|
|
|
N162
|
44.56 d
|
57.38 d
|
101.95 d
|
|
29.57 abc
|
30.77 b
|
111.13 d
|
171.47 e
|
|
|
N216
|
45.17 d
|
61.87 bcd
|
107.05 bcd
|
|
28.99 bc
|
32.22 b
|
125.61 c
|
186.83 d
|
|
|
N270
|
43.66 d
|
69.93 a
|
113.59 ab
|
|
31.62 a
|
38.01 a
|
137.96 b
|
207.58 c
|
Note: Different letters in a row are significant differences among treatments in each year (P<0.05). DI: drip irrigation, SI: micro-sprinkler irrigation, FI: flooding irrigation. N0: 0 kg N ha-1, N162: 162 kg N ha-1, N216: 216 kg N ha-1, N270: 270 kg N ha-1. VT: tasseling, R6: physiological maturity.
Table 4 Nitrogen translocation efficiency and contribution of post-tasseling to grain as affected by the different irrigation methods and nitrogen application rates.
Year
|
Irrigation
method
|
Nitrogen application rate (kg ha−1)
|
N translocation (kg ha−1)
|
N translocation
efficiency (%)
|
Contribution of N translocation to grain (%)
|
N assimilation (kg ha−1)
|
Contribution of N assimilation to grain (%)
|
2017
|
DI
|
N0
|
49.18 a
|
48.96 a
|
48.51 a
|
52.26 e
|
51.49 b
|
|
|
N162
|
45.27 ab
|
39.16 bcd
|
31.76 b
|
97.43 cd
|
68.24 a
|
|
|
N216
|
44.22 ab
|
36.34 cd
|
25.93 b
|
126.17 a
|
74.07 a
|
|
|
N270
|
45.82 ab
|
35.63 cd
|
26.11 b
|
129.71 a
|
73.89 a
|
|
SI
|
N0
|
43.05 ab
|
45.32 ab
|
44.65 a
|
53.33 e
|
55.35 b
|
|
|
N162
|
37.76 b
|
34.06 cd
|
29.63 b
|
90.25 d
|
70.37 a
|
|
|
N216
|
45.70 ab
|
37.48 cd
|
31.30 b
|
100.20 cd
|
68.70 a
|
|
|
N270
|
41.17 ab
|
32.85 d
|
27.41 b
|
108.96 bc
|
72.59 a
|
|
FI
|
N0
|
48.03 ab
|
48.11 a
|
48.60 a
|
50.70 e
|
51.40 b
|
|
|
N162
|
45.94 ab
|
39.36 bc
|
31.87 b
|
98.51 cd
|
68.13 a
|
|
|
N216
|
44.30 ab
|
36.19 cd
|
27.40 b
|
117.66 ab
|
72.60 a
|
|
|
N270
|
42.43 ab
|
33.53 cd
|
25.85 b
|
121.87 a
|
74.15 a
|
2018
|
DI
|
N0
|
36.23 cd
|
48.98 a
|
47.08 a
|
40.73 f
|
52.92 f
|
|
|
N162
|
49.17 ab
|
47.06 ab
|
37.96 bcd
|
80.43 de
|
62.04 cde
|
|
|
N216
|
48.80 ab
|
43.75 abcd
|
30.91 ef
|
110.07 a
|
69.09 ab
|
|
|
N270
|
48.55 ab
|
41.42 cd
|
30.52 f
|
111.45 a
|
69.48 a
|
|
SI
|
N0
|
27.08 e
|
43.69 abcd
|
39.50 bc
|
41.60 f
|
60.50 de
|
|
|
N162
|
41.60 bc
|
40.80 cd
|
37.56 bcde
|
69.52 e
|
62.44 bcde
|
|
|
N216
|
45.83 ab
|
42.81 bcd
|
36.49 bcdef
|
79.79 de
|
63.51 abcde
|
|
|
N270
|
43.97 abc
|
38.67 d
|
31.86 def
|
93.99 bc
|
68.14 abc
|
|
FI
|
N0
|
32.31 de
|
48.79 a
|
41.32 ab
|
45.84 f
|
58.68 ef
|
|
|
N162
|
44.15 abc
|
44.53 abc
|
33.51 cdef
|
87.40 cd
|
66.49 abcd
|
|
|
N216
|
51.42 a
|
45.74 abc
|
33.87 cdef
|
100.16 abc
|
66.13 abcd
|
|
|
N270
|
50.05 a
|
43.46 abcd
|
31.88 def
|
107.10 ab
|
68.12 abc
|
Note: Different letters in a row are significant differences among treatments in each year (P<0.05). DI: drip irrigation, SI: micro-sprinkler irrigation, FI: flooding irrigation. N0: 0 kg N ha-1, N162: 162 kg N ha-1, N216: 216 kg N ha-1, N270: 270 kg N ha-1.
Table 5 Effects of different irrigation methods and nitrogen application rates on the nitrogen use efficiency indicators in summer maize.
Year
|
Irrigation method
|
Nitrogen application rate (kg ha−1)
|
NHI (%)
|
NUE (%)
|
AEN (kg kg-1)
|
PFPN (kg kg-1)
|
2017
|
DI
|
N0
|
66.73 abc
|
-
|
-
|
-
|
|
|
N162
|
67.01 abc
|
38.28 bcd
|
25.95 bcd
|
73.58 a
|
|
|
N216
|
68.83 a
|
45.02 a
|
32.52 a
|
58.10 c
|
|
|
N270
|
67.96 ab
|
40.08 bc
|
27.96 bc
|
47.46 e
|
|
SI
|
N0
|
65.71 bcde
|
-
|
-
|
-
|
|
|
N162
|
67.20 abc
|
40.71 bc
|
28.76 ab
|
71.79 a
|
|
|
N216
|
67.49 ab
|
42.33 ab
|
29.83 ab
|
57.59 c
|
|
|
N270
|
66.18 bcd
|
37.00 cde
|
24.74 cd
|
46.42 e
|
|
FI
|
N0
|
65.08 cde
|
-
|
-
|
-
|
|
|
N162
|
63.76 e
|
33.11 ef
|
19.89 e
|
69.09 b
|
|
|
N216
|
65.79 bcde
|
34.67 def
|
23.36 de
|
54.09 d
|
|
|
N270
|
64.12 de
|
32.46 f
|
20.28 e
|
45.89 e
|
2018
|
DI
|
N0
|
67.16 b
|
-
|
-
|
-
|
|
|
N162
|
70.09 a
|
44.14 ab
|
33.11 ab
|
63.95 a
|
|
|
N216
|
71.80 a
|
50.23 a
|
38.63 a
|
52.67 c
|
|
|
N270
|
70.16 a
|
42.74 ab
|
31.34 bc
|
43.51 e
|
|
SI
|
N0
|
69.79 a
|
-
|
-
|
-
|
|
|
N162
|
70.63 a
|
46.73 ab
|
33.59 ab
|
65.22 a
|
|
|
N216
|
71.34 a
|
47.40 ab
|
34.64 ab
|
52.32 c
|
|
|
N270
|
70.68 a
|
41.62 ab
|
29.81 bc
|
43.38 e
|
|
FI
|
N0
|
66.37 bc
|
-
|
-
|
-
|
|
|
N162
|
64.81 c
|
42.76 ab
|
26.70 c
|
57.18 b
|
|
|
N216
|
67.23 b
|
39.32 b
|
26.86 c
|
49.88 d
|
|
|
N270
|
66.42 bc
|
39.29 b
|
26.14 c
|
42.80 e
|
Note: Different letters in a row are significant differences among treatments in each year (P<0.05). DI: drip irrigation, SI: micro-sprinkler irrigation, FI: flooding irrigation. N0: 0 kg N ha-1, N162: 162 kg N ha-1, N216: 216 kg N ha-1, N270: 270 kg N ha-1. AEN: agronomic efficiency of applied N, NHI: N harvest index, NUE: N use efficiency, PFPN: N partial factor productivity.