水稻の蒸散に関する研究 (1)

抄録

This experiment was carried out in order to obtain the relationship between transpiration rate of a rice plant and meteorlogical factors under the natural conditions and to make clear the effect of various wind velocities on transpiration rate of a rice plant, in Summer, 1954 and 1955.
We supposed that the transpiration is similar to the evaporation, that is to say the rice plant is an inanimate object, and according to this supposition the coefficient of transpiration (T/S) was calculated, and the result of this experiment was analyzed.
(T: Transpiration rate, S: Saturation deficit of air)
The apparatus of measuring transpiration was very similar to Craddock's apparatus for measuring dew fall, and it was set up as Fig. 1.
The daily amounts of transpiration from one rice plant are shown in Table 1, and it is apparent that transpiration rate per L n was highly correlated with solar radiation. (L: Top length n: Steam number)
Fig. 2 illustrates the typical daily marches of transpiration rate, and they are shown to be due to variation in the radiation and the saturation deficit of air. And in the daily marches of T/S, the large value appeared about at 8h and 14h, (see in Fig. 2) and its large value in the morning may be due to the difference between air temperature and leaf temperatur. But we roughly recognized the following relation between T/S and the solar radiation.
T/S∝R^1/2∼1/3
The effect of various wind velocities on T/S was not so clear in this experiment, (see in Table 2) however there seems to be the tendency that T/S increases in proportion to the wind velocity with in the limit of 6m/s, and if the wind velocity is beyond this limit, T/S shows either the constant value or the small reduction.
On the reason of above could not be understand for certain whether it is caused by bending of stem or not.