Vergara - 1976 - Physiological and morphological adaptability of ri

CLINIATIC mrurswca on Pnorosiwn. IESIS AND RESPIRATION 229
the leaf temperature occurred when the treatment was switched from 25°C of
leaf temperature to 31°C and simultaneously from dark to light. The tiseillation
period was about l7 minutes and the peak of oscillation in photosynthesis yvas
in accordance with the trough of oscillation in leaf temperature. From these
facts. it seems that the oscillations observed here are dependent upon stomatal
movement.
Temperature and dark respiration
The temperature-photoasnthesis curve of plants may be partially influenced by
dark respiration, especially at high temperature. The temperature coefficient
(Q10) for respiration of rice leaves is usually near 2.0 at temperatures between l5
and 40°C (Yamada et al.. 1955). The temperature response of respiration. as
shown in Fig. 2. may differ with plant organs. Tajima (1965) indicated that
the respiration of rice roots increased rapidly with increasing temperature up to
32°C. then more slotvly’, until an optimum was reached at 38°C. followed by a
decrease. while the respiration of rice leaves increased linearly with increasing
temperature in the range between 20° and 44°C. It was also found that the
decline in respiration of rice roots at a high temperature “was not restored by the
addition of glucose as respiratory substrate. but the inhibition in cytochrome c
oxjrdase activity‘ of rice roots was restored by the addition of soybean lecithin.
which stabilized the thermal deviation of cell membranes.
Munakata et al. (1970) round that the relationships between temperature
and respiration rates of leaf blade. leaf sheath. ear. and root were well fitted by
Oxygen upldte (n1 0 dry wfli h")
6
| | |
O_H|
0 2O 26 32 38 44
Tevflflerultre (°C)
2. Effect of temperature on respiratory‘ rates of leaves
and roots of rice plants (Tajima, I965).