Angelica acutiloba Kitagawa plants were cultivated in Ebb & Flow system to determine the optimal plant density. For each plant to attain uniform and maximal growth, a distance of 23 cm or more between plants was necessary. The distance, however, was 11. 5 cm between plants for the economically best yield with some uneven growth. In this case, the yield was 3.74.9 times that with the conventional soil culture.

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Under 33 °C high air temperature conditions in deep hydroponic culture, the effect of nutrient solution temperature on root activity was studied. Spinach plants (Spinacia oleracea L. cultivar 'Okame') were raised and their growth, soluble sugar content, and ion and water uptake were measured and analyzed. In the first experiment, the solution temperature of all treatments was initially set at 20 °C, then raised to 20, 26, 30, and 34 °C each for 3 days. When solution temperature was above 26 °C, root growth was inhibited and sugar content increased. Thus for high nutrient solution temperature, there is a disturbance in the carbohydrate metabolism of the roots, which is a major factor in growth inhibition. In the second experiment, plants were grown in four different solution temperature treatments (20/20, 26/20, 30/20, and 34/20 °C in light/dark periods) each for 12 days. The plants in the 30/20 °C treatment had good ion uptake and root growth. The soluble sugar content also was the lowest of all of the treatments. This indicated that even if the solution temperature was raised to 30 °C, the carbohydrate metabolism recovered due to the cooling of the solution during the dark period. The carbohydrate metabolism of the roots exposed to the 34 °C treatment could not recover.

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Factors affecting multiple shoot induction from single shoots and cotyledonary nodes of buckwheat seedlings, and from single shoots excised from multiple shoots were examined. More multiple shoots were induced from single shoots than from nodes derived from 1-week-old seedlings. Single shoots excised from multiple shoots further proliferated multiple shoots in half strength of modified Murashige & Skoog's medium containing 20μM benzylamino purine, 30 g/l sucrose, and 0.15g/l Gellan Gum at 6 week intervals. The multiplication rate was about 20. It was calculated that 20⁸ shoots could be propagated from a single shoot per year. Plantlets were regenerated by rooting from single shoots in the medium containing 1μM indolebutyric acid and the rooting rate was about 60%.
Acclimatization of in vitro plantlets was achieved by culturing in large vinyl bags for 10 days at about 65% acclimatization rate. Micropropagation procedure for buckwheat was established and the application and improvement of the technique are discussed.

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The effects of the ozone concentration on the sterilization of vegetables such as spinach, lettuce, and strawberries in preservation vessels were investigated. The vegetables were placed in a preservation vessel and continuously treated with air of ozone concentrations of 0.05ppm and 0.5ppm for 7 days at a temperature of 5±0.5°C and a relative humidity of 92.5± 2.5%. The following results were obtained.
1) The ozone concentration had no recognizable effect on the decrease of the fresh weight and the respiration rate of the vegetables in a preservation vessel.
2) The number of bacteria on the surface of vegetables decreased to about 1/2-1/3 of that with no ozonation at an ozone concentration of 0.05 ppm and there was almost no detection of bacteria at an ozone concentration of 0.5 ppm.
3) At an ozone concentration of 0. 5 ppm, the growth of fungi on strawberries was almost prevented for 7 days preservation. However, it was observed that the strawberries became decolored after 4 days by an ozonation with a concentration of 0.5 ppm.

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A present measurement and control system is very expensive, because machinery (sensor, motor, etc.) needs an exclusive line and software for operation. And it is hard to modify the software of the system flexibly when the machinery altered. Moreover it is difficult to control plural machinery at the same time.
Recently, the new system has developed. This system can measure and control plural machinery at the same time economically through the Internet. Name of this system is OpenPLANET (Open PLatform for Appliances NETworking).
In this paper, we applied this system to the Plant Factory. Especially we developed new sensor and machinery for distributed measurement systems.
In the future, this system (OpenPLANET) will realize a Low Cost Plant Factory.

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The appropriate amount of irrigation for plant cultivation varies according to the weather, temperature and plant size, and thus is difficult to estimate. However, if the stem diameter can be correlated with light intensity, temperature, humidity and water uptake, the amount of irrigation water can be regulated by measuring the stem diameter.
Takaichi et al. (1995) reported that the growth rate is correlated with light intensity, such that stem diameter decrease with increasing light intensity. However, they used a reflectiontype visible laser sensor to measure the stem diameter, which is cost prohibitive for general application. In the present study, we used low cost full bridged strain-gauges composed of film elements which measure the change in electrical resistance produced by the bending of the stem to measure stem diameter.
The experiments were conducted on tomato plants (Lycoperusicum esculentum) in a green-house.
The strain-gauge output, growth rate, water-uptake rate, light intensity, temperature and humidity were measured twice, on each of 4 consecutive days in summer and fall. Strain gauge output changed slightly in response to light intensity, suggesting a correspondence to change's in stem diameter. The output value (stem diameter) was also found to correlate with temperature and water-uptake rate, such that an increase in temperature was related to an increase in the water-uptake rate, a decrease in the diameter of the apical plant of the stem, and an increase in the diameter of the basal part of the stem.
Thus, the present results suggest that the water-uptake rate can be estimated by the stem diameter measured using a low cost full bridged strain-gauge.

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