Yoshida - 1981 - Fundamentals of Rice Crop Science

MINERAL NUTRITION OF RICE 143
Table 3.21. Concentration of nitrogen in culture solution used for different periods.
Nitrogen concentration (ppm)
Treatment
23 Jun- 10-13 13 Jul- 4-13 13-26 26 Aug- 3 Sep-
10 Jul Jul 4 Aug Aug Aug 3 Sep 14 Oct
1 1.0 1.5 3.0 3.8 3.0 2.0 2.0
2 1.5 2.1 4.2 5.1 3.9 2.5 2.4
3 2.0 3.0 6.0 6.8 5.0 3.2 2.9
4 2.5 4.2 8.5 9.2 6.5 4.0 3.5
5 3.5 6.0 12.0 12.4 8.4 5.0 4.2
6 5.0 8.5 17.0 16.7 10.8 6.4 5.0
7 7.5 12.0 24.0 22.5 14.0 8.0 6.0
by the plant. It appears when total nitrogen uptake reaches 170 mg N/plant.
Thus, the first peak appears at stage II when the nitrogen concentration in the
culture solution is high, and it appears at later growth stages when the
concentration is low.
• The second peak appears at stage VI (from 19 to 9 days before heading),
when the nitrogen concentration is moderate. This corresponds to the time
when young panicles are growing actively.
• When the nitrogen concentration is high, there is no second peak. Thus, the
most efficient time to supply nitrogen for grain production varies with the
level of nitrogen supply.
Table 3.22. Partial productive efficiencies of nitrogen for grain
and straw. a
Treatment
Stage
I II III IV V VI VII Vlll IX
1 39 46 58
2 35 41 57
3 37 43 73
4 36 59 67
5 39 64 58
6 33 62 47
7 35 64 41
1 102 117 121
2 102 126 130
3 108 141 112
4 111 123 113
5 113 122 98
6 116 113 83
7 114 115 74
Grain
67 73 75 53
70 69 56 50
65 55 58 38
60 35 47 30
35 23 41 21
26 22 21 20
26 24 16 16
Straw
125 107 66 45
111 86 50 10
97 88 46 5
91 63 10 21
75 62 16 8
58 34 22 28
52 34 19 18
23 10
41 13
22 4
21 9
12 –45
21 2
–6 –
14 50
26 30
14 4
10
–
34
–
2 12
21 –
a Kimura and Chiba (1943).