Yoshida - 1981 - Fundamentals of Rice Crop Science

160 FUNDAMENTALS OF RICE CROP SCIENCE
Table 3.29. Absorption and translocation of iron, and ironexcluding
power of the rice plants grown in culture solution
deficient in various nutritional elements. a
Status of
plant
Complete
– N
– P
– K
– Ca
– Mg
– Mn
Iron content (ppm)
Upper Lower Culm
leaves leaves stem
423 732 390
398 830 495
458 864 407
617 983 808
544 910 413
602 998 480
601 826 570
Translocation Ironpercentage
of excluding
iron b power c (%)
3.5 60
2.5 60
3.7 30
4.5 20
4.6 22
5.5 27
5.4 38
a Tadano (1976). b Amount of iron translocated to the shoot relative
to the total amount of iron absorbed by the plant. c Defined as
formula: ( a – b )/ a × 100 (%), where a is the amount of iron, in
milligrams, contained in the same volume of culture solution as
that of water absorbed by the plant and b is the amount of iron, in
milligrams, actually absorbed by the plant.
3.11.5. Varietal performance on iron-deficient and iron-toxic soils
Some degree of varietal difference in the ability to absorb iron appears to exist
(Fig. 3.26). When 12 rice varieties were grown on synthetic soil with different
moisture regimes and at different pH values, plant color differed greatly, as
illustrated by the chlorophyll content of leaves. Variety Tetep showed a consistently
high ability to absorb iron from the synthetic soil. Varieties also differ in
their tolerance for iron toxicity (Ponnamperuma 1976a).
3.1 2. MANGANESE
3.12.1. Occurrence of deficiency and toxicity
Manganese deficiency and toxicity seldom occur in field-grown rice. There are,
however, reports on manganese deficiency of lowland rice grown on highly
degraded paddy soils in Japan (Hashimoto and Kawamori 1951) and manganese
toxicity from areas affected by manganese mining (Iwata 1975).
3.12.2. Manganese in soil solution
Concentrations of manganese in the soil solution increase after submergence (Fig.
3.27). Manganese is more readily reduced and rendered soluble than iron. The
release of manganese into the soil solution, therefore, precedes that of iron. This
increase in availability of manganese is beneficial for rice at a near-neutral pH. In
solution culture, 0.1–0.5 ppm Mn is sufficient for maximum rice growth and
concentrations higher than 10 ppm are toxic (Ishizuka et al 1961, Tanaka and
Navasero 1966a).