Vergara - 1976 - Physiological and morphological adaptability of ri

TEhPERATtJRE AND \-"EGET.-\Tl\-'E GROVUTH 173
plants: it was 33°C for paddy and upland rice. Yamada (1958) reported similar
results for protoplasmic streaming in pollen tubes Of two rice varieties. The
streaming rates increased with temperature from 15° to 30°C. and then decreased.
The ceasing of protoplasmic streaming in root-hair cells at low temperatures
occurred between 0° and 10°C, with a large dispersion among experiments (Doi,
I950). This large dispersion is due to the difficulty ofestiination. The situation is
similar to the estimation of the lower limit of germination temperature of seeds.
Ilo\\-'e\~'er_ it can he said. at least. that the streaming occurred at temPhratures as
low as near 0°C in some instances. The ceasing of streaming at high temperatures
occurred between 40° and 45°C for a number tifiice varieties (Doi. 1950). The
heat death of cells occurred at temperatures very close to those for the ceasing of
protoplasmic streaming (Fig. 5).
Figure 6 shows the cffcct of temperature on the ratc of protoplasmic streaming
in root hair cells of rice seedlings (Doi. 1950). The original author did not include
Tarrnermure t°c 1
52
I
48 Q
I
O
O O
440 O
O O
O O
O O
40- O
out i i i 1 i i
52
I
.
4B O O
I I
I O
44 Q
O
O
O
I
O
O
O
49- O O
ROOT
Q:l=i i | l | | I
I 5 IO 2O 3O 4O 5O 60
Treorrnenitrnin}
5. Etiect of hot water on death of grovi-"ing points in rice
seedlings (Doi, 1950). Q = dead; Q =living.