Relationships between Environmental Conditions and Production-and Consumption Activities of Individual Leaves in the Population of Rice Plant in a Party Field : II. Effects of temperature on photosynthesis and dark respiration of individual leaf of different position

摘要

This experiment was carried out to know the effects of air temperature on photosynthesis and dark respiration of individual leaf of different position. 1. In each of continuous temperature treatments (30°C, 25°C and 20°C day temperature; night temperature was 5°C lower, respectively), the photosynthetic rate of the 10th leaf (the uppermost expanded leaf) was not changed remarkably for the first 6 days; then gradually declined, but those of the lower leaves decreased during that period and became smaller as their positions lowered and they declined earlier than the upper leaf. 2. The photosynthetic rate at 17°C decreased markedly and that at 30°C increased a little comparing with that at 25°C. The 8th leaf was especially sensitive to low temperature and the difference of photosynthetic rate between the 8th and the upper leaves became greater with time of the temperature treatments. 3. Photosynthetic recovery of the leaves which received stress at 17°C for 1 day or 3 days and transferred to 30°C or 25°C was more rapid, as shorter the cool temperature duration and higher the transferred temperature. Older leaves recovered more slowly from temperature stress. 4. The respiration rates increased with increase of temperature, but changed to a small extent. The decreasc of respiration rate at low temperature was greater than that of photosynthetic rate. The ratio of respiration rate to photosynthetic rate of the 8th leaf was somewhat higher than the upper leaves.