A set of experimental system for the study on the root system-soil interaction for laboratory work was presented. This system consisted of the following apparatuses and associating techniques for operation; (1) a handy-type root box covered with a mirror sheet, (2) a pinboard which enabled sampling of the root system in the root box soil as it stood in the soil, (3) a piece of holed polyethylene sheet for handling during the sampling of the root system and preserving the root system without impairment and disarrangement after sampling, (4) a transmitted light box for taking photograph of the root system. Techniques associating with those apparatuses consisted of the soil filling up into the root box, supplying water to the root box, washing out the root system from soil, and staining the sampled root system.
Distribution patterns of soil porosity and moisture, and daily changes of soil temperature in the root box soil, were determined. Our soil filling-up technique gave high reproducibility as well as uniform porosity distribution in the root box soil with small difference among the root boxes. No significant differences were found in the soil moisture content at a given depth of horizontal soil layer. When the root box was put into the trench, the soil temperature in the root box was closer to that of a natural soil profile than when it was placed on the ground. Upland rice and maize were grown in the root box placed in the trench. Root systems sampled showed considerably uniform profiles among triplicated plants for both species. These results demonstrate the significance of preparation and control techniques of soil environments for the study on root system-soil interaction.

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Seedlings of tomato cv.‘Fukuzyu No. 2’, eggplant cv.‘Hayabusa’fand sweet pepper cv.‘Shinsakigakemidori’were raised with 12 cm pots containing 1 bark compost: 1 soil (v/v) with NPK each 2 kg/a for 47 days, and then transplanted in a vinylhouse under three levels of basal fertilizer application (NPK 2, 4 and 6 kg/a, respectively) in order to clarify the effects of fertilizer application on their growth, early yield and root development.
1) The growth of top was promoted in the following descending order, tomato, eggplant and sweet pepper by an increase in level of basal fertilizer application, but the early yield was lowered under high fertilizer level except for sweet pepper. Tomato with high ratio of fruit weight to leaf weight showed low root weight compared with eggplant and sweet pepper with the low ratio.
2) The yield clearly correlated with the number of thick roots over 1 mm in diameter in each crop tested. The distribution of root system in eggplant showed wider and deeper than that of the other crops in correspondence with the number of thick roots.
3) Nitrogen content in the root was enhanced by increasing the level of fertilizer application in each crop. It was observed that starch content in the root was positively correlative with the number of thick roots, showing higher starch level in eggplant with a lot of thick roots than the other crops.

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This experiment was carried out to examine the effects of time of water supply on the growth of seedlings and their yield in eggplant, cv.‘Hayabusa’.
1) The growth of seedlings was affected by time of water supply. Especially noon watering induced vigorous growth with a higherS/Rvalue at transplanting time, while morning watering arrested the growth accompanying by a lowerS/Rvalue.
2) Seedlings received morning watering during the period of raising seedling grew faster and established a deeper and wider root system consisting in a lot of thick roots over 1 mm in diameter after transplanting, resulted in the highest yield compared with those grew under noon or evening watering.
3) The more number of thick roots over 1 mm in diameter had the plant, the higher its yield. Then there was found a close correlation between the number of thick roots and yield.
4) Seedlings which showed lowerS/Rvalue with larger leaf area at transplanting time produced higher yield in vinylhouse. There was a correlation between this value and yield.

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This paper reports the heat insulation characteristics of a greenhouse with movable fourfold curtains: uppermost film of ethylene-vinylacetate copolymer, second film of reflective aluminized polyethylene, third film and fourth film of ethylene-vinylacetate copolymer (Figs. 1-3) .
Orchid culture room was heated by two air-heaters. This house has reasonable high heat insulation characteristics of K (=1.75 kcal/m²hr°C) .
Radiative and convective heat transfers were calculated using network analogue model (Figs. 4 and 5) under two conditions: radiative infinite reflection between wet films and radiative transmission through partially dry films.
Calculated heat resistances (Tables 1-3) show considerable decrease at dry films but in general there was little difference in the resistances between these two conditions. Fourfold curtains can not be recommended for commercial use.

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Great progress has been made in the development of plant factory. New artificial light source as called pulsed light illumination has been developed, which is operated on high frequency and could be controlled in different duty ratio. So, electrical power is being expected to be saved by applying the pulsed light illumination in the plant factory.
In this study, system identification method was used to estimate the effect of the pulsed light illumination on the photosynthesis of Okayama Saradana. Impulse responses of net CO₂uptake to 100%, 50%, 30% duty ratio of the pulsed light illumination were estimated in 1000 ppm, 650 ppm, 350 ppm CO₂concentration respectively. Simulation with the estimated impulse responses showed that the net CO₂uptake under low duty ratio of the pulsed light illumination such as 50% could be kept in the level of that under 100% duty ratio, 350 ppm CO₂concentration if CO₂concentration of the environment is increased to two or three times of 350 ppm. So, by means of controlling the duty ratio and the CO₂concentration, much electrical power could be saved in the cultivation of the plant factory.
Furthermore, the estimated changes of net CO₂uptake to various duty ratio of the pulsed light illumination had a good agreement with the changes observed in the short-term. So, it could be concluded that system identification is a very effective method for estimating the effect of the pulsed light illumination for the plant factory.

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