In order to make clear the relationship between environmental conditions and structure of plant community, the time courses of the vertical variations of light and temperature were observed in artificial plant communities of Fagopyrum esculentum with three planting densities (400, 100 and 25 plants per 1m²) at the farm in Toridemachi, Ibaraki prefecture on 2nd-3rd and 16th-17th July 1955, in parallel with the analysis of the structure of those plant communities by “the stratifying clip method”.
Light factor: Relative light intensity was measured with two electric photocells under diffused light (e. g, immediately after sunset). The vertical distribution of light intensity was firstly dependent on the leaf density and the height of leaf layer of plant community, secondly on the inclination of leaves, which increased when leaves had wilted and closed their stomata under the stronger solar radiation and water deficiency.
Temperature factor: The daily changes of vertical distributions of air temperature within plant communities and in an open land were measured with a series of thermometers (10cm. long) shaded by thicker white papers, and that of earth temperature with a series of L-tube earth thermometers. The daily temperature courses observed in air and soil-layer were respectively shown as sine curves with the period of one day by means of harmonic analysis. The vertical thermal diffusibility was obtained from such calculation that the difference of amplitude between two heights was put into the solution of the differential equation of heat conduction. Regarding air temperature, with the increasing density of the plant organs, especially of leaves, at each height above the ground, the amplitude and the vertical thermal diffusibility became smaller and the phase later. However, the amplitnde and the phase seemed dependent not only on the leaf density at each height but also on the vertical distance from the upper surface of plant cover to that height.
In the plant community the upper surface of plant cover was heated by day and cooled by night, as well as the ground surface. The daily variation of heat quantity accumulating in plant Immunity by day and dispersing from it by night were expressed by sine curves, which were obtained by combining one sine curve showing the daily change of transporting heat through the upper surface of plant cover with the other sine curve showing that through the ground surface. Consequently, it was known that the daily change of such a heat quantity within the plant community was mainly dependent only on the leaf density in the upper surface of plant cover.
Temperature of leaf was measured with a thermocouple at its lower surface. The hot junction was made so sharp and the leading wire adjacent to the hot junction was so fine that the heat conduction from the leaf was considerably depressed. The temperature of leaf exposed to the sun light was 0.5-1.0°C higher than the surrounding air temperature under general wind velocity, but that of shaded leaf was about 1.0°C lower. In the night, however, the difference of temperature between the leaf and the surrounding air could be hardly recognized.

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The first kaiyô (leaf development) date together with the number of subsequent kaiyô (leaf development) in an important index from view points of the phenological and sericultural problemes. Followings are the summary of this paper:
The first kaiyô date of the leaves of mulberry (Morus argutidens KOIDZ and Morus alba L. var.) depends clearly on the March mean monthly air temperature. This relationship was confirmed both by data for many years at one point and by data for 1955 at about ten points. It seems that the effect of the March mean monthly air temperature upon the kaiyô was stronger at a cold point where the first kaiyô date was late. Comparing the data observed at about ten points, it can be said that, in the last ten days of April and the first ten days of May, the earlier the first kaiyô date came, the less the rate of the number of kaiyô (leaf development) was. But, regarding every single point, it was smaller in the later ten days than in the former ten days. Experimental formulae were obtained for these relationships in the periods mentioned above.

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Observations of the number of the mulberry (Morus alba L. var.) leaf developmenton May 7, 1955 were made in Okuchichibu Mountain region, at where the valley runs almost east or east-southeast. The distributions of the number of kaiyo (leaf development) on the slopes facing south in the observed area are shown in Fig. 1. Using the relation obtained in another paper, the March mean monthly air temperature was estimated from the number of the leaf development. Result of the comparison of the difference between the estimated values and the observed values at two weather stations was±0.2°C. In conclusion, the local climatic differences in this area were as follows:
(1) As an average state of March, the slopes facing south were warmer in about 1°C than those facing north.
(2) As compared with this marked evidence, there was no clear tendency along the river course.
(3) Differences from place along the river course were 1.0-1.2°C. This is considered as the cross-section shape of the valley as shown in Fig. 2.
(4) The greatest difference caused by the different shape of the cross-section was shown on the slopes facing north, secondly in the valley bottoms, and then on the slopes facing south.

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The experiments of prevention against frost damage by “heavy-oil-burning” in apple orchard were carried out at Suzaka in Nagano Prefecture at the nights of 20-21 April, 13-14 May, 1955. The area of experimental field was about 36×33sq. meters and oil-burning was continued from 3:02 a.m. to 5:00 a.m. on 14 May, 1955.
The results obtained are as follows:
1) Before burning the inversion level was formed at the height of 2m.
2) During burning the inversion level rose to the height of 2.5m, approximately, and the temperature rise was 3.9°C in the layer below the inversion level in 1 hour after firing, 1.5°C at the inversion level in 1.5 hour after firing and 2.4°C in the layer above inversion level in 13/4 hour after firing.
3) The maximum value on the horizontal distribution curve of temperature was 3.5°C at the height of 1.5m. at the center of the field, in 1 hour after firing. The warm air region was transferred from the west part to the center of the field and then returned westward conversely.

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Recently, studies on the wind over cultivated fields have been put forward by Inoue and others, however, those on the air flow amongst the stalks have scarcely been carried out.
The author describes the result obtained primarily of the velocity of the horizontal airflow, intensity of turbulence and the scale of turbulon amongst the stalks in the paddy rice field of Mishima (Shizuoka Pref.) at August 29th, 1955.
Making use of the hot-wire anemometer (Platinum, diameter 0.04mm, length 50mm), the horizontal components of the air flow amongst the stalks at the height of 40, 55, 70, 85, 100cm are recorded for the averaging time of 90 seconds, and the results are analysed by reading in every 0.5 seconds.
The result are as follows:
1) The velocity of the air flow amongst the stalks at each height are shown to be from 12 to 22cm/sec, in spite of 220cm/sec at 200cm height as shown in Fig. 1 and Tab. 1.
2) The intensity of turbulence (<u'²>^1/2/u) are nearly constant with height.
3) T_u (the passage time of the horizontal largest turbulon) were obtained at each height from Fig. 2, and the scale is calculated by ∧_u=uT_u……(1) The scale of the horizontal largest turbulon ∧_u obtained from (1) is nearly constant with height as shown in Tab. 1, and the magnitude is of the order of about 1×10²cm.
4) Roughness parameter z₀ is estimated from the distribution of wind velocity measured by small-type Robinson anemometer at the most prosperous stage of tillering in paddy field, the ratio α(=h/z₀) is found to be 0.39-0.42, which is to be in comparison with 0.35-0.39, reported previously at same stage, where is the height of rice plants.

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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.

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Some agro-meteorological investigations on drought were made from the viewpoint of precipitation, but the most important factor, which has influence on drought damage, is the soil moisture storage of the field.
The author estimated the potential evapo-transpiration from the monthly mean temperature, and calculated the water balance at Fukuoka. Some results of the calculation were shown in Table 1.
Water deficient occures in June, July, August and September, and it does not occure in the other monthes (see Table 2-5). The amount of precipitation has the greatest influence on the water deficient, and the effect of the potential evapo-transpiration is not so great. The effect of the soil moisture storage of the previous month is not negligible. August is the most dangerous month of drought, among 66 years, water deficient is recognised in 16 years and in the other 19 years, the soil moisture storage decreases for want of precipitation. July comes after August.
When the water deficient is recognised, it suffers from drought. Table 6. shows the remarkable drought damage in Fukuoka Prefecture, and the soil moisture storage and water deficient at Fukuoka.
Generally speaking, water deficient is useful as the index of drought, but they correspond not exactly. Because (1) Water requirement of plant differs with its growth stage, (2) Calculation of water balance was made in monthly data.

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It is desirable that the width of wood belts is narrow in a small farm land. But it is not clear what is the relation between the width of the wood belt and its reductive effect of wind velocity, and when we expect to prevent wind erosion in the inland, what is the relation between the number of belts in the shelter-hedges and the reductive effect of wind erosion. In order to find out these, the following researches have been made.
In the wind tunnel experiment we used hedges of 1 to 8 belts made of Japanese cypress twigs 7cm. high and 25 to 30 covering degree and investigated U′/U×100 the wind velocity ratio between in front of and behind the hedges. (U′: for the wind velocity when there are hedges. U: for that when there is none.)
In the experiment in a cultivated field, we used hedges with 1 to 6 belts made of pine twigs, a meter high and 65 to 70 covering degree and investigated V′/V×100 the wind velocity ratio. (V′: for the wind velocity at each station. V: for the standard wind velocity at a meter above the ground.)
The results of these experiments are as follows.
1. In both experiments, the wind velocity ratio just behind the hedges decreases with increasing of the number of belts, but at the distance of 15 times the hight of the hedge (X/H) the recovery of wind velocity ratio begins to grow quicker.
2. In both experiments, the more the belts of hedges, the higher gets the point of the maximum wind velocity, and the bigger the wind velocity ratio.
In proportion as the number of belts increases, the point of the maximum wind velocity gets father to the leeward of hedges in the wind tunnel experiment, but in the outdoor experiment, it was almost fixed (constant).
3. As to the relation between the number of belts and the covering degree, when a three-belted hedge with 25 to 30 covering degree and a single one with 80 to 90 covering degree are comparedd with each other, the maximum wind velocity ratio is bigger, but the recovery of wind velocity ratio on the lee is quicker in the latter.
4. As to the relation between the width (the number of belts) of the wood belts and the reductive effect of wind velociy, the wind velocity ratio remarkably decreases with increasing of the number of belts, but even if the number increases further, it does not decrease so much. And so, it seems that no bigger reductive effect of wind velocity can be expected.
5. The results of the wind tunnel experiment and that in the cultivated field are fairly in accord with each other.
6. As to the relation between the width of the wood belts and the covering degree, a single hedge with big covering degree rather than with small covering degree and with belts increased in number, gets quicker recovery of wind velocity ratio at the distance of 10 times the hight of the hedge and farther on the lee, though the decrease of wind velocity ratio is big about the hedge on the lee. But in order to prevent wind erosion, a single hedge with big covering will satisfactorily serve the purpose, the preventive function of the hedge being around to 12 times the height of the hedge on the lee.

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