Yoshida - 1981 - Fundamentals of Rice Crop Science

MINERAL NUTRITION OF RICE 125
Table 3.8. Effect of H 2 S concentration and contact period on the
wilting of rice seedlings. a
A) Long contact with H 2 S solution.
Av
Wilted leaves (%) after contact of
concn
of S (ppm) 0 h 24 h 43 h 48 h 66 h 90 h 139 h 288 h b
2.7 0 0 17 39 67 72 83 85
1.7 0 0 22 22 61 62 62 64
1.3 0 0 6 6 22 27 21 41
0.7 0 0 0 0 0 5 0 29
0.4 0 0 0 0 11 9 7 42
0.07 0 0 0 0 0 0 0 42
0.00 0 0 0 0 0 0 0 0
B) Short contact with H 2 S solution (2.9 ppm S).
Contact period
Wilted leaves (%) after
contact was discontinued for
24 h 48 h 96 h 240 h
0.5 h 0 0 0 0
1.0 h 0 0 0 0
2.0 h 0 0 0 10
Contact continued
240 h 0 0 60 67
Check 0 0 0 0
a Mitsui (1960). b Contact discontinued after 90 h.
sufficiently long, leaves will wilt even at a concentration of 0.07 ppm. As the
concentration increases, wilting occurs after a much shorter period of contact
(Table 3.8).
Hydrogen sulfide inhibits nutrient uptake with a short period of contact and
before the wilting becomes visible (Fig. 3.6). The inhibition is not the same for
different nutrients. The percentage decrease in uptake ranges from 3% for CaO to
143% for P 2 O 5 . Actually, concentrations of K 2 O and P 2 O 5 in culture solution
increase with hydrogen sulfide treatment, which implies that these nutrients have
slower uptake rates than water. The inhibition of nutrient absorption by hydrogen
sulfide appears to follow the order: P 2 O 5 > K 2 O > SiO 2 > NH 4 - N > MnO > H 2 O
> MgO > CaO. Other respiratory inhibitors (sodium cyanide, sodium azide, and
butyric acid) also retard nutrient uptake in a manner similar to that of hydrogen
sulfide.
Besides inhibiting nutrient uptake, hydrogen sulfide enters the roots, moves into
the shoot, and disturbs growth and translocation. Hydrogen sulfide retards translocation
of carbohydrates, nitrogen, and phosphorus from the basal part of the
culm to the growing organs. The accumulation of those nutrients in the culm may