Water and nutrient consumption (supply) of hydroponic tomato in a greenhouse is identified and is estimated by using neural nets. Learning procedure of the nets is backpropagation. Inputs are time series data of 4 environmental conditions (solar radiation, inside temperature, inside humidity and CO₂ concentration) and outputs are water and nutrient consumption of hydroponic tomato. Data used in the present study were measured in a commercial greenhouse of Yokogawa Green Farm in Itsukaichi, Tokyo from 9 Dec, 1990 to 17 Jan, 1991. By using a neural network which has single hidden layer with 4 units, the amounts of water and nutrient consumption are estimated well.

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A method of estimating the growth rate of rice cells in suspension culture has been proposed by Nursery Technology Inc. The estimation is based on the differential uptake of NH₄⁺ and NO₃^- ions by rice cells from a medium, which is reliably monitored by the change in medium pH values during culture.
0.5g of rice cells were inoculated into 100 ml of a liquid medium including 7 mM of NH₄⁺, 28 mM of NO₃^- and 5 mM of MES (pH5. 8). The cell weight increased by 16-25 times after 2 weeks of suspension culture. During the culture, medium pH values decreased from the initial 5. 8 to 4. 0 and later increased to 5. 3.
The pH values of the medium are largely affected by NH₄⁺/NO₃^- uptake by the rice cells. It was demonstrated that the NH₄⁺ addition to the culture medium caused an increase in pH values, and a decrease in NO₃^- uptake by cell caused an increase in pH. In our rice culture experiments, NH₄⁺ was depleted within the first week of culture, however NO₃^- concentrations gradually decreased throughout the culture period. The decrease in pH of the medium observed at an early stage of the culture is due to decreased NH₄⁺ uptake. The increase in pH at a late stage can be explained by reduesed NO₃^- uptake in the absence of NH₄⁺ assimilation.
Because some nitrogen uptake is closely related to that of cell growth, the following formulas were used to estimate the fresh weight of the rice cell culture in the early and late stages of culture.
Formula for an early stage :
α∫ (5.8-pH) dt=W for d (pH) /dt<ξ
Formula for a late stage :
β (pH (t) -pH (t-1)) =W for d (pH) /dt≥ξ
Where α, β and ξ are constants, t is the number of days of culture, and W is the rice cell weight at time t.
Observed rice cell weights in suspension culture experiments were compared to those estimated by the above formulas, and the formulas were found to yield good estimations. The formulas are applicable to an alysis of the influence of NH4+ on the cell growh in cultures of other plantspecies.

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We developed a pilot scale plant of a plant factory equipped with fluorescent lamps to closely illuminate plants, and painted the inside white to effectively use the reflected light (close illumination method). In this paper, the light-energy saving effect of the close illumination method on lettuce cultivation was investigated experimentally and theoretically by employing this pilot scale system.
(1) The mean light intensity on the cultivation panel (area of 12 m²) was as high as 650 μE/m²/s (45 klx), when 42 fluorescent lamps (110 w) were placed 30 cm above the cultivation panel and illuminated. The coefficient of utilization (U), which indicates the light utilization efficiency in the growth room, was about 1. 7. The measured value of U agreed well with the value calculated by Moon's equation, and was nearly 3 times higher than high pressure sodium lamps placed about 100 cm above the cultivation panel.
(2) One hundred and twenty stocks of lettuce/day (75 g fresh weight/plant) were produced in a cultivation area of 24 m² (12 m²/bed × 2 layers), 29 days from the germination. Also, the fresh weight of seedlings weighing about 0.2 g increased by about 40 times in 9 days.
(3) The lighting power consumption and total power consumption for the production of lettuce (75 g/plant) was about 1.1 kwh/plant and 2. 5 kwh/plant, respectively. Thus, the lighting power consumption was about half that of conventional high pressure sodium lamps. On the other hand, the lighting power consumption for the production of seedlings weighing about 10 g/plant and 0.2 g/plant was about 0.3 kwh/plant and 0.06 kwh/plant, respectively.
(4) Utilizing close illumination with fluorescent lamps, 3 layers of planting beds were vertically stacked for seedling cultivation, and 2 layers for growth. Thus, a compact cultivation system was achieved using the close illumination method.

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Mass propagation of bulblets from tissue cultured bulbscales of Lilium auratum Lindl. through simple tissue culture process using shake- and jar-fermentor culture techniques was investigated. The tissue culture operation was improved by simplifying the separation and/or division of bulblets propagated in vitro for subculture as; (1) separation of bulbscales from bulblets using forceps, (2) cutting the bulblets without roots into pieces using surgical knife, (3) cutting the bulblets with roots into pieces using surgical knife. Differentiation and growth of bulblets (number, weight etc.) were satisfactory level in all cases. The operation time for subculture was reduced to 1/4 by cutting the bulblets using surgical knife. The bulblets were mass propagated easily using jarfermentor.

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In plant growth factories, it is necessary that we use computer environmental control systems for integrate control and continuous plant production. Development of computer software for advanced the environmental controllers is important to produce high quality plants and to save production costs. An environmental control software development support system with using object-oriented programming techniques was developed and tested. Smalltalk/V and PC-9801 desktop micro-computer (CPU : i80386) were used for the development support system implementation. Four classes were defined for constructing environmental controller model of the development support system.
The results of several tests suggested that the development support system with excellent graphic user interface had sufficient performance for testing advanced environmental control algorithms and debugging environment control software. It is considered that high reusability of the object-oriented programming techniques helps accumulation of many pieces of developed environmental control software to make large software property for development advanced the environmental controllers.

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