Vergara - 1976 - Physiological and morphological adaptability of ri

174 CLIIMIATE AND RICE
Rate of streaming (p. lsec)
I5
Q | I l | I |
0 5 0 I5 20 25 3O 35
6. Etfeet of temperature on the rate of protoplasmic
streaming in root hair cells of riee seedlings (Doi, 1950).
(The lilies on dots were added by the present author.)
the lines in the figure: these were drawn by the present author. These two lines
intersect around 14°C. Thus. the thermal characteristics of protoplasmic streaming
change at this temperature. Three other figures in the original paper give interseeting
temperatures ofapproximately l6.0°C (for seedlings grown at 15°C).
165°C (grown at 20°C) and 155°C (grown at 25°C).
Thus, the temperature range for protoplasmic streaming extends from 0°
to 45°C for root-hair cells of rice seedlings. However, the optimal range for the
streaming is approximately from 15° to 33°C.
GENERAL DISCUSSION
Four critical temperatures
Through the survey’ ofliterature in this I't‘,\"t6\‘V,
a regularity emerged concerning
the reactions of rice plants t0 temperature. The regularity is that several critical
temperatures are common through different kinds of physiological propeities.
The temperature range at which riee seeds can germinate is from near 0° to
45°C; the range at Wllltll‘! the germination occurs optimally is 18° to 33°C. The
temperature range for the occurrence of protoplasmic streaming extends from
0° to 45°C for root-hair cells of riee seedlings; the optimal range is approximately
from 15° to 33°C.
Respiration and photosynthesis occur from near 0°C to 45°—50°C; these
activities. hovrever, notably decrease at temperatures below 15°C or above
32°C under some conditions (eg. photosynthesis under high light intensity).