The purpose of this study is to analyze the thermal environment inside greenhouse by means of system identification and to indicate the applicability of system identification. The experiment was carried out in a vinyl house with the floor area of 58 m² and the surface area of 190 m² in July and August of 1991.
At first, the authors investigated the mechanism which determines the thermal environment inside greenhouse under no ventilation. The assumed mechanism is shown in Fig. 1. The measurement points in this experiment are shown in Fig. 2. Figure 3 is the block diagram of the heat flow which expresses the assumed mechanism of Fig, 1.
The results of identification of a system with an input of radiation outside greenhouse and an output of air temperature at the point 2M are shown in Fig. 4. The calculated air temperature is in good accordance with the measured air temperature. The step response indicates that increase of 1 kW⋅m^-2 in radiation causes increase of about 30°C of inside air temperature. Figure 5 shows the relationship between order and error in identification of the system.
The results of identification of a system with an input of air temperature at the point 2L and an output of air temperature at the point 2M are shown in Fig. 6.
Figure 7 shows the measured and calculated air temperature at the point 2M. Calculation was executed according to the block diagram of Fig. 3 from radiation outside greenhouse.
Furthermore, the authors investigated the mechanism where the thermal environment inside greenhouse is determined by both radiation and ventilation. The block diagram of system which determines air temperature at the point 2M based on radiation outside greenhouse and on-off of ventilating fan is shown in Fig. 8. Figure 9 shows the results of identification, indicating that system identification is effective in analysis of condition with on-off of ventilating fan.
Figure 10 shows the results of identification of the same system of Fig. 4. In Fig. 10, identification was made for every 3 hr and the calculated air temperature was linked. The calculated air temperature is in much better accordance with the measured air temperature than that of Fig. 4, indicating that system of greenhouse is changing slowly and that the latest data is needed for more precise calculation of the system.

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Composting heat generator is a low level heat source compared with those using combustion of fuels such as petroleum and LNG. Because it is low level in temperature, composting heat generator will not be applied to heat recovery system unless it is designed to restrict energy loss and exergy dissipation as little as possible. Exergy is known to be useful to evaluate the availability of every kind of energy not only from its quantity but also from its quality.
For optimization of a target heat recovery system from composting heat generator, mass, energy and exergy balances must be predicted properly under any possible operating condition. Because there is a temperature difference between the heat generator and medium fluid in a heat exchanger inserted in the generator, temperature does not become uniform in the generator. In order to predict the amount of energy and exergy recovered from such heat generators of non-uniform temperature in detail, the balance equations must be treated microscopically.
In the present paper, microscopic balance equations of mass, energy and exergy in the composting heat generator are derived systematically, following a transport phenomena model with chemical reaction for porous or dispersed media. Then, the balance equations are simplified to equations of practically available form, because the mass flux by diffusion can be neglected compared with that by convection under the usual aerating condition of composting.
The amount of heat and exergy possible to be recovered will be theoretically predicted by solving the balance equations derived here with suitable boundary and initial conditions introduced for the target heat recovery system.

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The validity of the microscopic balance equations proposed in Part 1 is discussed, based on the experimental results of heat recovery from a composting heat generator using a trial heat exchanger.
The calculated result of the final apparent density of compost materials packed in the generator is about 10% larger than the experimental result, because there was a gravitational leakage of water from the bottom of the generator in this experiment. However, the calculated results of temperature in the generator, temperature of medium fluid at the outlet of the heat exchanger, and distributions of the generated heat and exergy show relatively good agreement with the experimental results of them. Therefore, the theoretical treatment based on the microscopic balance equations seems likely to be valid to simulate the heat recovery system from the composting heat generator.
In this experiment, maximum amount of exergy possible to be recovered is about 4%, which is smaller than the value previously estimated under the assumption of perfect mixing of compost materials. It is due to heat conduction occurring in the generator during heat recovery.
On the other hand, the amount of exergy actually recovered by medium fluid is merely 0.3% of the whole amount of exergy generated in composting, and almost all the amount of generated exergy is lost out of the heat generator or dissipated due to irreversibility of the process.
To make larger the enthalpy and exergy efficiencies, the following methods will be advantageous, that is, 1) Introduction of external heat recovery system from exhaust air out of heat generator, and 2) Change of the medium fluid in the heat exchanger from water to air.

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Carrot seed was selected to determine the most appropriate ozone exposure condition which promote the germination percentage and early growth. The ozone gas from an ozonizer with an oxygen bomb was mixed to clean air and was introduced into an exposing and germinating vessel.
The high level exposure conditions consist of some ozone concentrations of 0-5 ppm and some exposure times of 24-72 hr, the other side, the low level conditions consist of an exposure time of 24 hr and some ozone concentrations of 0-2 ppm.
At the high level conditions, the germination percentage was slightly progressed and the mean days of germination was more uniform when the long exposure. However, the early growth was obstructed at the high concentration.
At the low level conditions, the germination characteristics were progressed through all ozone concentrations, particularly, the germination percentage rose to about 77% from 60% of general case at the low ozone concentration. The early growth also increased at low concentration, the fresh weight of top was about 1.34 times and that of root was about 1.65 times of the control. On the other hand, the dry weight of top was about 1.32 times and that of root was about 1.2 times, respectively.

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The effects of short day and low temperature on sink activity and mineral absorption of strawberry plant ‘Nyoho’ during raising period were investigated. The propagated young plants were exposed to the short day (8 hr) and the low temperature (DT/NT=25/10°C) for 2 weeks with or without following 2 weeks night chilling (DT/NT=greenhouse ambient/10°C) treatment.
The root dry weight increased by night chilling treatment. In the leaf, the total carbon contents decreased, and phosphorus and potassium contents increased by either short day or low temperature treatment. The translocation of ¹³C-assimilates to the root decreased by either short day or low temperature treatment, but increased by following night chilling treatment. The sink strength in the root also increased with night chilling. The similar tendency was observed in sink activity in the crown.
It is concluded that night chilling treatment increased sink activity in the crown and the root to enhance translocation of photosynthetic products from the leaf to the root. The accumulation of photosynthates might stimulate the crown and root development and contribute to the flower formation.

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Effects of flooding on the growth and physiological changes of seven grape rootstocks, 3309, 3306, 101-14, 5BB, SO⋅4, 110R, and H.F. were examined. The 3-year-old pot grown rootstocks propagated by cutting were flooded to the soil surface for 9 weeks beginning from June 3 in an unheated plastic house. Flooding tolerance judged by the shoot growth and the overall injury symptoms, such as leaf chlorosis and leaf fall, varied greatly among rootstocks. The highest tolerance was observed in 3306 and SO⋅4 rootstocks, followed by 3309, 101-14 and 5BB, while 110R and H.F. were sensitive to flooding. Although the number of aerial roots per plant was larger in H.F. than in 110R and SO⋅4 rootstocks, no significant difference in the emerging time of aerial roots was observed among rootstocks. Regardless of rootstock, the chlorophyll content of leaves and root activity estimated from TTC reduction were decreased by flooding, whereas ethanol content of fine roots was increased, but the relationships between flooding tolerance of rootstocks and these changes were not clear.

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