Yoshida - 1981 - Fundamentals of Rice Crop Science

MINERAL NUTRITION OF RICE 139
Table 3.17. Nitrate content in tissues of rice and cucumber 0–7
days after treatment with nitrate nitrogen in culture solution. a
NO 3 –N
Plant concn in
Plants parts culture
solution
(ppm)
Nitrate content
(mg N/g fresh wt)
0 day 3 days 5 days 7 days
Rice
Roots 20
200
Leaves 20
200
0.03 0.83 0.52 0.83
0.03 0.88 0.69 1.09
0.02 0.27 0.26 0.42
0.02 0.33 0.45 0.67
Cucumber
Roots 20 0.01 0.46 0.35 0.33
200 0.01 0.61 0.61 0.78
Leaves 20 0.01 0.15 0.01 0.00
200 0.01 0.42 0.22 0.15
a Oji and lzawa (1974).
1975b). Under such condition, the rate of nitrate assimilation into organic nitrogen
appears to slow down in rice (Dikshoorn and Ismunadji 1972).
Ammonia appears to suppress manganese absorption at near-neutral pH (Table
3.18), but manganese absorption increases with increasing pH. At pH 6 and 7, the
manganese content of leaves and roots is much lower with ammonia than with
nitrate.
Table 3.18. Effect of solution pH and source of nitrogen on
manganese content of the rice plant. a
Mn content (ppm)
Nitrogen Dry wt (a)/(b)
source pH (g/plant) Leaves Roots
(a) (b)
3.5 13 70 20 3.5
4 36 80 20 4.0
NH 4 5 41 460 200 2.3
6 44 610 560 1.1
7 19 680 2200 0.3
3.5 24 90 30 3.0
4 39 290 30 3.6
NO 3 5 39 830 280 3.0
6 24 1000 3310 0.4
7
9 1380 6260 0.2
a Tanaka and Navasero (1966a).