Daily changes in the highest leaf surface temperature were measured in the summer of 1978 at Heiwa Avenue, Hiroshima, where plants were suffered severe drought conditions.
The leaf surface temperature exceeded the ambient temperature at any time during the measurement. The leaf surface temperature of non-sclerophytes grown in Hiroshima showed as high as that of desert plants. Daily changes of the leaf surface temperature were classified as three types; Radiation type in which the maximum leaf surface temperature was attained at the highest intensity of solar radiation. Air temperature type in which the leaf surface temperature indicated almost constant values during the day time where the air temperature showed scarce change, and Compromised type. Average differences in temperature between the air and the leaf surface in Radiation, Air temperature and Compromised type were 13, 6 and 10°C, respectively.

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The feedback information about plant growth is needed in the computer control system to optimalize the environment for maximalizing production. The present paper reports a method for evaluating physiological and pathological states of cucumber plants, by means of image processing of reflectance of plants or leaves in different wave length regions of light. From the analysis of spectral reflectance of cucumber leaves, it became clear that states of plants can be characterized by respective reflectances in wave length regions of 650-690 nm (R) and 800-1000 nm (I), and evaluated by the ratio of two reflectances. So, R- and I-images of reflectance were taken by the vidicon camera through filter systems having transmitting peaks at 670 nm and at 900 nm, respectively, and digitized in a mesh of 240×256 words (6 bits/W) . The physiological and pathological states were observed clearly in the digital display of those images. In order to obtain an index for evaluation of those various states of leaves, the ratio (Br) of reflectances in I- and R-images was calculated from Eqs. (2) and (3) . In general, the reflected light intensity varied with the angle of incidence of light, owing to the specular and spread reflections. However, this disturbance caused by the angle of incidence was eliminated enough to characterize the spectral reflectance of leaf by using Br. So, the Br was examined in various states of cucumber leaves. On the basis of the fact that the frequency distribution of Br of normal leaves was approximately normal, the interval containing 99% of total of Br's of normal leaves was given as 7.6≤Br≤12.7, and Br= 7.6 and Br= 12.7 were used as the classifiers for discrimination between normal and abnormal (damaged and diseased) leaves. Thus, the present method for image processing of reflectance of plants made it possible to obtain a feedback information about vigor of plants, which can be used in an on-line computer system for environmental control of plant growth.

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Effects of circulation frequencies of cultural solution after planting on growth, and fruit yield and quality were studied, in solution culture of tomato plants bearing only two trusses and planted in high density.
Tomato plants, which had grown at low dissolvedoxygen concentration in cultural solution from the stage of young seedlings, did not show wilt-symptom and root-rot at the low dissolved-oxygen concentration of 1.3 ppm after planting and could survive even at the concentration of 0.9 ppm which was maintained about 2 hours.
The relation between dissolved-oxygen concentration after planting and occurrence of puffy fruits was investigated. The degree of puffiness was indicated with specific gravity of fruit. The specific gravity of fruit which had marketable quality was above 0.90. In the culture of the plants sown from August to April, circulation frequencies of cultural solution in the nighttime (6 p.m.-6 a.m.) were decreased to 15 minutes in every 360 minutes almost until fruit setting in the second truss was ensured. After fruitsetting in the second truss, circulation frequencies of cultural solution in the nighttime were increased up to that in the daytime (6 a.m.-6 p.m.), which were 15 minutes in every 60 minutes. Such circulation frequencies for controlling dissolved-oxygen concentration prevented overgrowth of foliage and ensured high yield of fruits without puffiness. In the culture of the plants sown in July, the circulation frequencies above mentioned for controlling dissolved-oxygen concentration producted cracking fruits.

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The relation between the distributions of the CO₂ concentration in soils and soil structures, as defined by CO₂ diffusion coefficient, was investigated. Changes in the distribution when the CO₂ concentration in a greenhouse had a diurnal variation also were investigated.
In the soil column in which the CO₂ diffusion coefficient was constant, the pattern of distribution expressing the relation between the CO₂ concentration and depth was an upward convex curve.
In the soil column in which the diffusion coefficient decreased with depth, the CO₂ concentration formed a distribution pattern that increased linearly with depth.
In the soil column in which the lower layers with a small diffusion coefficient became thicker and upper layers with a larger coefficient topped on them, the pattern was a concave in the upper and convex in the lower layer.
In the soil column which had a smaller coefficient in the upper layers and a larger coefficient in the lower ones, the pattern was an upward convex curve.
Three distinct patterns were formed in soil structures difined by the diffusion coefficient : 1) convex upward, 2) straight, 3) concave in the upper layer and convex in the lower layer.
These patterns did not vary unless the soil structures changed, even when the CO₂ concentration in a greenhouse changed diurnally.
The required ventilation hours to maintain the CO₂ concentration in a greenhouse differed depending upon whether the amounts of CO₂ generated from soil surface were constant during the whole day or were proportional to the difference between the CO₂ concentrations in the greenhouse and in the soil surface.

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