Microscopic balance equations of mass, energy and exergy were derived for a deodorization system using soil cover. Applying the balance equations to the practical case of the system, concentration of an odorous gas component and temperature were simulated, and the contents of exergy dissipation and their variation with time and location were discussed. There are six kinds of irreversible processes in this system, that is, heat conduction, mass transfer, frictional loss due to viscosity, dissolution or volatilization of odorous gas components, evaporation or condensation of water, and chemical decomposition of odorous gas components. These processes are accompanied by the exergy dissipation E_d1, E_d2, E_d3, E_d4, E_d5, and E_d6, respectively. Of all the six kinds of exergy dissipation, E_d3 is exclusively greater than the others. According to the results of the vertical distribution of the dissipation terms, it is found that heat conduction (E_d1) and evaporation or condensation (E_d5) occur mainly near the top and bottom parts of the soil bed, frictional loss due to viscosity of gas (E_d3) occurs near the top part, and dissolution or volatilization of odorous gas components (E_d4) occurs uniformly in the soil bed. The microscopic exergy analysis presented here is useful in understanding the temporal and spatial variations of irreversible processes occurring in the system, and therefore useful in considering the effective utilization of the system.

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An optimum control problem for the first stage of the composting process was formulated based on the variational principle. The whole period for the composting process can be divided into three sub-periods, i.e., temperature increasing period, stable temperature period, and temperature decreasing period. The optimum control problems for the first two subperiods were numerically solved individually. It was found that 1) the aeration rate in the 1st sub-period should be low in order to raise the temperature of the compost mass as fast as possible to the value at which the composting reaction rate reaches the maximum, and 2) a much higher aeration rate is necessary in the 2nd sub-period than in the 1st sub-period so as not to accumulate excess heat generated in composting. Although the theory described in this paper was obtained for the batch-type composting process, this theory can be extended to a continuous system by replacing the sum of the 1st and 2nd sub-periods of composting process to the retention time in the vessel for compost mass.

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Mixing an aggregate-like soil Akadama (red sphere) or artificially made aggregates with other non-aggregate soil for water retentivity improvement makes it possible to get a “most desirable” property for plant growth. An analytical approach to the prediction of soil water retentivity for aggregate mixing is proposed for cases where the hydraulic properties between aggregate and non-aggregate soil are distinctly separable and verified, using both the bulk volume mixing ratio and the space occupation ratio, assuming that the bulk density of non-aggregate is kept constant in the mixture. Mixing was defined and discussed volumetrically in this model on the basis of the“closest” packing concept of aggregates which Spomer (1980) called the“threshold proportion.” After determining both the space occupation ratio by measuring various densities and the bulk volume mixing ratio, we can estimate the contribution of water retention from each constituent component by conventional techniques, and summing them up volumetrically gives a mixture retentivity at a specified potential. This summing up is valid only when soil water is equilibrated thermodynamically. Measured mixture curves are located between unit aggregate and nonaggregate soils. The comparison between measured and calculated values has shown fairly good agreement, which secures the validity of the estimation proposed.

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Ball et al. identified that the concentration of K⁺ in leaves of Avicennia marina decreased under high salinity conditions in a culture solution. With this K⁺ decrease in the leaf, the photosynthetic capacity declined. This effect suggests the concentration of K⁺ in leaves and the soil water salinity are limiting factors in mangrove vegetation. We examined this hypothesis using A. marina, Rhizophora stylosa and Bruguiera gymnorrhiza in this study. This study was done in the Republic of Djibouti where the pure forest of A. marina is widely distributed and on Iriomote Island in Okinawa where R. stylosa and B. gymnorrhiza are distributed. The relationship between the concentration of K⁺ in leaves and the soil water salinity in R. stylosa and B.gymnorrhiza revealed no significant correlation. However, this relationship in A. marina revealed a significant correlation. And then, the relationship between concentrations of Na⁺ and K⁺ in leaves in R. stylosa and B. gymnorrhiza revealed no significant correlation. However, this relationship in A. marina revealed a significant correlation. These results may suggest that the effect caused by the concentration of K⁺ in leaves and the soil water salinity in A. marina is a limiting factor in the distribution of A. marina, but that hypothesis cannot be applied to R. stylosa and B. gymnorrhiza.

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Runner plants of “Nyoho”strawberry plants were exposed to different light intervals during storage ; i. e., day/night cycles of 8/16 h, 8/16 h for 3 d followed by 0/24 h, 8/40 h, 8/88 h, and continuous darkness, and the effects on flower-bud formation, leaf growth, and chlorophyll and carbohydrate concentrations were investigated. Succulent elongation of petioles, decreased leaf area and etiolation of leaflets improved as light intervals were shortened. Although carbohydrate concentrations and percentage of flower-bud formation in continuous darkness were lower than in plants with 8/16 h, these values did not decrease even when the dark intervals became prolonged to 8/40 h.

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Calcium (Ca) is an important macronutrient for soybean production, and its absorption and translocation are influenced by environmental factors. Therefore, the effects of 12 and 16 h photoperiods with and without water stress during the seed-filling stage of soybean on the distribution of Ca was studied by using the radioisotope (⁴⁵Ca) as a tracer in leaves, petioles, and stem within nodes. Univariate and multivariate analyses (Manova) showed the main effects of photoperiod, water stress, and plant tissues on Ca distribution to be highly significant (p<<0.001) . The 16 h photoperiod increased the Ca concentration in top leaves compared with the 12 h photoperiod. Water stress significantly (p<0.001) modified the pattern of Ca distribution and reduced its concentration in plant tissues within nodes irrespective of photoperiod.

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Soil-mix moisture in a plug tray with limited-volume can be easily changed by watering and evapotranspiration from a plug sheet consisting of plug seedlings, soil mix and a tray. Thus, timing and amount of watering are most important parts of skills in plug seedling production. An automatic ebb-and-flood watering system for controlling soil-mix moisture in a plug tray was developed and applied to tomato plug sheets. A plug tray with 128 cells (2.8 L/tray volume) was used for the experiment. The plug sheets were placed on a bench with an ebb-and-flood system. A plug sheet located in the center of the bench was weighed with an electric balance by suspending it from a steel frame. When integrated evapotranspiration of the plug sheet, estimated from decrease in weight of the plug sheet, reached over a setpoint of 1 100 g/tray during the daytime, all the plug sheets were watered from below. After the water in the bench drained, the integrated evapotranspiration was reset to zero. In this way, soil-mix moisture in the plug tray was controlled accurately in a proper range for growth of the plug seedlings during the culture period.

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A closed hydroponic system was established in the cultivation of single-truss tomato, where the drainage was utilized for improving the fruit quality. Tomato (Lycopersicon esculentum Mill) plants were grown in a “wet-sheet culture” (WSC) bed, where a water-retaining sheet (non-woven fabric) was used as a growing medium to supply nutrient solution. Nutrient solution with EC 1.2 dS m^-1 was applied by tube irrigation. Supply of the solution was controlled with a level sensor, and surplus solution was overflowed from the bed and preserved into a reservoir tank. Tomato seedlings were transplanted to the WSC bed in a density of 10 400 plants 10 a^-1 at early June in 1997, and main shoots were pinched after the anthesis of the first truss. On an average, 20 to 30% of daily-supplied nutrient solution was overflowed as drainage. At the final stage of ripening, the preserved drainage in the tank was concentrated to EC 5.0 dS m^-1, and re-supplied to the bed instead of fresh solution. By the end of the harvest, all the preserved drainage was used up by the plants, and no waste solution was drained out of the greenhouse. Moreover, fruit cracking, which frequently occurred under high temperature conditions, could be completely prevented by the application of the concentrated drainage, possibly due to the salinity effect.

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In order to investigate the effects of ornamental foliage plants on the thermal environment and comfort inside a room, experiments were carried out in a room in Ehime University in the spring and summer of 1997. In the spring experiments, environmental factors in five treatments by the combination of kinds of ornamental foliage plants and arrangement were measured and analyzed. The ornamental foliage plants were Schefflera arboricola “Hong Kong” and Dracaena fragrans “Massangeana.” In our previous experiments, the former had shown the highest transpiration rate and the latter had shown little transpiration. The evapotranspiration during 7: 00 and 18: 00 of Schefflera arboricola “Hong Kong” in line at the window was 781 g⋅pot^-1, which contributed to the estimated increase in relative humidity of 26%. An amenity effect by the increase in humidity by ornamental foliage plants can be expected in spring as well as in winter. In the summer experiments, environmental factors in four treatments were measured and analyzed. The evapotranspiration during 6: 00 and 18: 00 of Dracaena fragrans “Massangeana” interspersed in the room was 172 g⋅pot^-1 and the increase in relative humidity was estimated to be 3%. This result indicates that an undesirable increase in humidity can be prevented by the appropriate choice and arrangement of ornamental foliage plants.

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A forced ventilation micropropagation system was developed, and with this system, single-node leafy stem cuttings of sweetpotato (Ipomoea batatas (L.) Lam., cv. Beniazuma) were cultured on cellulose plugs or vermiculite used as supporting materials with Murashige and Skoog (1962) nutrients but without sugar, i.e., photoautotrophically. The inlet CO₂ concentration of the system was 1 500μmol mol^-1 and the photosynthetic photon flux on the culture shelf was 150μmol m^-2 s^-1. The net photosynthetic rate and dry mass of sweetpotato plug plantlets from the forced ventilation treatment on day 22 were 30-40 times and 4-6 times greater, respectively, than those of the plantlets grown under the conventional, photomixotrophic micropropagation system with natural ventilation and gelled agar medium containing sugar.

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To investigate the relationship between growing temperature and the outbreak of bacterial soft rot in Zantedeschia (calla), eight ornamental cultivars were planted in soil mix in plastic trays and placed in a growth cabinet under either a 32/27°C or a 25/20°C day/night temperature regime. The plants grown at 25/20°C showed a lower rate of soft rot infection, although variation was observed among cultivars. Tuber pieces of five cultivars were planted either on a rockwool cube (75×75× 50 mm high) or in soil mix in plastic pots as controls, and irrigated from the bottom. The plants grown on rockwool cubes showed a lower rate of soft rot infection than those in soil mix.

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