This paper presents applications of a‘speaking plant’-based intelligent control technique to dynamically optimize hydroponic cultivation and fruit-storage processes. Tomato growth during the seedling stage was optimized by nutrient concentration of a hydroponic solution in a cultivation process. Similarly, for the storage process, the rate of water loss in tomatoes was minimized by temperature control. The control system comprises a decision system and a feedback control system. The former is used for determining the optimal set point profile (l-step set points) of the environment based on plant responses, whereas the latter controls the environment based on the optimal set point profile. The optimal set point profile of the nutrient concentration of the solution during the seedling stage was a slightly high level (1.4mS/cm) during the first few days, a markedly low level (0.3mS/cm) during the second few days, a slightly high level (1.6mS/cm) during the third few days, and the maximum level (2.0mS/cm) during the last stage (flowering stage of the first truss) under the range of 0.3 to 2.0mS/cm. This operation promoted reproductive growth of the tomato. In the storage process, on the other hand, the optimal temperature operation that first rises to a high level (40°C) for a day and then suddenly drops to the minimum level (15°C) under the range of 15 to 40°C provided lower values of the rate of water loss than when the temperature was maintained constantly at the lowest level throughout the entire control process. These results suggest that dynamic optimization using a speaking plant-based intelligent control technique is useful for qualitative improvement of both the plant during cultivation and the fruit during storage.

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Seedlings of a typical short-day plant, morning glory (Pharbitis nil Choisy cv. Violet) were exposed to different light qualities under a 16-h light period, which was longer than the critical daylength. Flowering occurred in blue light, but not at all under the light qualities of green, red or white. Irradiation with white light (consisting of 50% blue light) for 14h per d also promoted flowering, while white light supplemented with near ultraviolet (UV-A) light had no effect on flowering. These results suggest that cryptochromes, blue-light receptors, influences flowering in morning glory under long-day conditions. Phytochromes did not seem to have any relation to flowering. Besides, after the investigation on growing temperatures of 18, 23 or 28°C under a 12-h light period, it was found that light quality hardly influenced flowering at 18°C, and flowering responses under blue light were promoted at 23°C especially. Stem elongation was significantly inhibited under blue light and under white light supplemented with UV-A.

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A decision and control system mimicking a skilled grower's thinking process is proposed which was then applied to dynamic optimization of the relative humidity that minimizes both the water loss and the fungal development of fruits during storage. A skilled grower's thinking process consists mainly of two steps: (1) “learning”through experience and (2) “selection and decision”through simulation of a mental model developed in his brain by the learning. After a decision, (3) “action”in a loose and/or sophisticated manner is taken. The decision and control system proposed here consists of two decision systems (I and II) and a fuzzy on-off controller for ventilation. The optimal set points of the relative humidity are first determined using decision system I, and then the relative humidity is controlled based on these set points using a fuzzy on-off controller. In decision system I, neural networks identify the water loss and fungal development of the fruit as affected by the relative humidity (“learning”), and genetic algorithms search for the optimal set points of the relative humidity that minimize the water loss and fungal development of the fruit through simulation of the identified model (“selection and decision”) . The optimal set points obtained here involved a slightly low humidity during the first few days after storage and then higher humidity. The fuzzy on-off controller tuned optimally by decision system II showed good control of the relative humidity. This control technique is widely applicable to dynamic optimizations of complex agricultural systems.

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Antioxidative enzyme activities and contents of chlorophyll, carotenoid and flavonoid in leaves of Cattleya and Cymbidium exposed to 40%, 70% and full (100%) sunlight for 80 days from August 1 were examined. Results obtained were compared with our previous data for the same orchids exposed to different irradiance from May 1. Antioxidative mechanisms of these orchids attributed to adaptation to sunlight with high intensity would be dependent on the season before and during adaptation. The chlorophyll contents in both orchids decreased by light of high intensities in both seasons (August and May), though changes in carotenoid and flavonoid contents were different in plant species and depended on light intensity. High protein content, dry matter concentration of the leaves and percentage of flowering indicate a possible relation with antioxidative function, that is the function of protection against strong light-induced injuries.

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Bulbs of‘Gander’ tulip subjected to usual precooling (15°C 3W+5°C 8W) were planted in beds with or without soil cooling tubes in early autumn. Soil cooling at 15°C reduced bud blasting and increased cut flower length and weight, but delayed flowering. When the bulbs were planted in late September and their temperatures were varied by changing the distance between bulbs and cooling tubes, the bulbs kept at 18-20°C resulted in 100% flowering in mid November without delay. Exposure of the bulbs to ethylene just after the lifting ensured high flowering percentages and improved cut flower quality even when they were grown under high soil temperature conditions. The bulbs planted in late September, kept below 20°C by soil cooling for 2 weeks and then transferred to an ambient condition resulted in the same flowering percentage and cut flower quality as those kept below 20°C by continuous soil cooling until their flowering.

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The effects of combination of temperature and fruiting on development of flower and internal components were investigated. The number of flowers decreased by more than 50% after fruits appeared. In the 30-20°C (day-night) temperature, the number of flowers had decreased to 2.7% of the peak 31-40 days after the first flowering occurred. The flower and ovary weights decreased in the fruiting treatments, and those tendency were more marked at high temperatures. Short-styled flowers were observed only in the fruiting treatments. Fruit growth was best in the 20-20°C treatment. The number of seeds was highest in this treatment and lowest in the 30-30°C treatment. Dry matter partitioning ratio to roots decreased as the day or night temperature became higher. This change was more marked in the late stage and was accelerated by fruiting. After day 20, the nitrogen content in leaves tended to be higher in the flower thinning state than in the fruiting state, and it changed little over time. In both the flower thinning state and the fruiting state, the phosphorus level in leaves after day 40 was much lower in the daytime 30°C than in the daytime 15°C or 20°C treatments. The phosphorus level in the 30-30°C flower thinning state was less than half the level recorded in the 15-15°C treatment. Both the calcium level and the magnesium level were higher in the fruiting state than in the flower thinning state at any temperatures.

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Light utilization of plants, growth, yield and quality were compared between tiller-keeping and tiller-removing cultivation for early shipment of sweet corn. The transmission rate of solar radiation to the ground in tiller-keeping cultivation was 10% less than that in tiller-removing cultivation, suggesting the light utilization was higher in tiller-keeping method. The leaf areas of plant in tiller-keeping and in tiller-removing cultivation were 7053 and 2953 cm², respectively. The root weight generated from culm base of a plant in tiller-keeping and in tiller-removing cultivation were 33.4g and 24.6g, respectively. These results suggest that tiller-keeping cultivation results in higher growth caused by its effective light-intercepting characteristics than tiller-removing cultivation. Sterility ear reduces the weight and quality of sweett corn. Productivity and quality of ears were compared among three cropping type using plastic greenhouse, plastic tunnel and plastic mulch. In each cropping type, fresh weights of a plant and ear were higher in tiller-keeping than tiller-removing cultivation, and the lengths of sterile part from the ear tip in tiller-keeping were shorter than in tiller-removing cultivation. Ear weight per plant was correlated negatively with planting rate, however, degree of decrease was smaller in tiller-keeping than in tiller-removing. These results confirmed that tiller-keeping cultivation results in effective light-intercepting characteristics to produce high yield and quality in sweet corn for early shipment.

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The relationship between the rate of temperature drop, observed by infrared video thermography, and leaf browning injury was investigated in Saintpaulia. The severity of leaf injury increased largely during the immersion of leaf (20°C) in water (5°C) for 10s, whereas no further increase in the severity of injury was observed thereafter. During 3s of leaf immersion at various temperatures of water, leaf injury was induced only when the rate of temperature drop was more than 3°C/s. In the case of decreasing leaf temperature from various initial temperatures (40°C, 35°C, 30°C), leaf injury was observed at smaller temperature difference between leaf and water when the initial leaf temperature was high. The rate of temperature drop was high when the leaf temperature at 33°C as dropped to 20°C (3.5°C/s) rather than from 23°C to 10°C (3.2°C/s), resulting in 53% and 32% injury on the leaf, respectively. The temperature drop of coated leaves following immersion in 7°C water showed a lower rate of temperature drop than uncoated leaves, resulting in 1/30 times of the injury in uncoated leaves. In addition, the severity of the injury decreased as the size of a water droplet decreased due to the slow drop in leaf temperature. The results suggest that a gradual drop in leaf temperature inhibits leaf injury even though the temperature difference between water and leaf is large.

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Reduction in electric energy consumption is important for minimizing resources used for sweetpotato propagule production in a closed transplant production system. The objective of this study was to test whether or not an increase in cell volume of a tray can reduce electric energy consumption for sweetpotato (Ipomoea batatas (L.) Lam.) vegetative propagation in a closed transplant production system. Single node cuttings each with one unfolded leaf were used as propagules and grown for 18 days at cell volumes of 20, 40, 60 or 80 mL with the same planting density of 643 m^-2 in all treatments (number of cells per tray was 98) . The number of harvestable propagules per stock plant did not differ significantly among cell volumes 6 and 10 days after planting, but increased with increasing cell volume 14 and 18 days after planting. The electric energy consumption per propagule for cell volumes of 20, 40, 60 and 80 mL was 0.54, 0.42, 0.34 and 0.26 MJ, respectively, corresponding to electricity costs of 2.2-2.4, 1.7-1.8, 1.4-1.5 and 1.0-1.1 Japanese Yen, respectively, 18 days after planting. Thus, increasing the cell volume of a tray is a useful method for reducing electric energy consumption per propagule for sweetpotato vegetative propagation in a closed transplant production system.

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We evaluated fruiting-associated changes in inorganic components in the leaves and fruit of muskmelon (Cucumis melo L.) during circulating hydroponics. The contents of chlorophyll a and b in leaves rapidly increased from the day of fertilization to 15 days after fertilization. However, as the harvest season approached, a marked yellowing with degreening was observed in the first node leaf of fruit-bearing branch. The rate of phosphorus content differed between main stem leaves and fruit-bearing branch leaves, showing a rapid increase 30 days or more after fertilization in the first node leaf of fruit-bearing branch. The rate of potassium content decreased in leaves nearer to fruit, showing a marked decrease in first node leaf of fruit-bearing branch as the harvest season approached. The rate of calcium content was higher in main stem leaves than in fruit-bearing branch leaves. The rate of magnesium content increased irre-spective of the location of leaves until the harvest season. Thus, the concentration of inorganic component in the leaves of muskmelon differed among the sites of leaves, and changes in each component were markedly affected by the growth of fruits, being more marked in leaf nearer to fruit. The yellowing with degreening observed in the first node leaf of fruit-bearing branch appeared to be due to potassium deficiency in the leaf.

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An unbonded type of gauge device was developed for continuous measurement of changes in stem diameter. The study was undertaken to examine the temperature drift of the device under different temperature conditions (8.8 to 36.8°C) and to determine its resolution of changes in tomato stem diameter for 3 days. The current data indicate that the temperature drift of the system was only 3μm for 10°C change and also that the changes in tomato stem diameter could be monitored continuously with high sensitivity with an error ranging from 2.1% to 3.5%. These results suggest that the method ensures to diagnose effect of temperature on tomato plant growth status at real time.

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Effects of ultrasonicated water treated with quartz porphyry“Bakuhan-seki” (UW-B) added on organogenesis in protocorm-like body (PLB) of Cymbidium and Phalaenopsis species cultured in vitro were examined. The medium supplemented with 2% UW-B brought good results on PLB formation of these species. The best results for inducing shoot with roots in PLB cultures were obtained by medium with 1% UW-B (C. insigne) or 2% UW-B (Phalaenopsis) . UW-B added to culture media was found to be efficient for proliferation of PLBs and subsequent shoot formation of both Cymbidium and Phalaenopsis cultures.

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Net photosynthetic and evapotranspiration rates of a grafted tomato-transplant community and microclimate around the transplant community during acclimatization using a plastic tunnel in a greenhouse were measured using micrometeorological and weighing method. When the tunnel was opened, net photosynthetic and evapotranspiration rates of the transplant community increased linearly with air current speed around the transplant community. The air current speed decreased almost to near 0 m s^-1after closing the tunnel. When the tunnel was closed, net photosynthetic and evapotranspiration rates of the transplant community were -0.02 mgCO₂m^-2s^-1and 3 mgH₂O m^-2s^-1, respectively. They were similar to the rates when the air current speed was almost 0 m s^-1with the tunnel opened. Therefore, decreased photosynthetic and evapotranspiration rates when the tunnel was closed were considered to be the result of inhibition of gas exchange between transplants and atmosphere engendered by decreased air current speed.

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