Establishment of an effective supplementary lighting procedure is necessary to increase the value of leaf lettuce grown using a hydroponic method involving a low production cost. In leaf lettuce extracts, quercetin, one of the flavonoids, was isolated and identified. It was investigated that quercetin has important functions that can be used as a dietary supplement. Flavonol synthase (FLS) is a key enzyme involved in quercetin biosynthesis, catalyzes the conversion of dihydroquercetin to quercetin. Therefore, we determined the sequence of the flavonol synthase gene (FLS) in red leaf lettuce. We harvested leaf lettuce grown using supplementary light sources, such as ultraviolet radiation B (UV-B), ultraviolet radiation A, blue, and red lamps during the night. It is noteworthy that FLS expression and the quercetin content were particularly increased to a greater extent in young leaves than in mature leaves when UV-B and blue light were used simultaneously at night. We suggest that UV-B with blue light is used simultaneously at night for producing leaf lettuce with high quercetin content.

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Two neural network (NN) models were developed to estimate evapotranspiration (ET) rate of New Guinea Impatiens (Impatiens New Guinea Hibrid). Inputs of one NN model were canopy temperature, environmental factors (air temperature, relative humidity, radiation), and the plant motion (optional). The plant motion was calculated using the top projected canopy area. The mechanistic model was used in order to provide a baseline with which to compare performances of the NN models. In non-drought stress condition, root mean square error (RMSE) between estimated and measured ET rate of the NN model with the plant motion (NNP), the NN model without plant motion (NN), and the mechanistic model were 21.80%, 22.04%, and 29.94%, respectively. In drought stress condition, RMSE of the NNP, the NN, and the mechanistic model were 39.02%, 49.81%, and 72.09%, respectively. The plant motion could contribute the better performance when the plants were in drought stress condition. The NN model could estimate the ET rate without parameters used in the mechanistic model.

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The general appearance of a plant is the most obvious indicator of its physiological well- being. Color Co-occurrence Matrix (CCM) texture features, extracted from a set of 1095 images were used to classify water stress in Sunagoke moss (Rhacomitrium canescens) using Neural Networks (NN). An Excess Green Water Stress Index (EGWSI) was developed and used to quantify water stress in the sample. The CCM texture features were extracted from: red-green-blue (RGB); hue-saturation-intensity (HSI) and CIE's (Comission Internationale de LEclairage) LAB and XYZ color spaces. The HSI texture features achieved 99.45% water stress classification efficiency. They were followed by RGB, XYZ and LAB texture features with classification efficiencies of 99.07%, 98.83 and 96.3% in that order respectfully. The HSI textures features displayed a higher ability and reliability to classify water stress in Sunagoke moss and can be used for stress detection under varying light intensities. A significant accomplishment of this study was the detection of both flood and draught water stress in a plant that exhibits a high level of desiccation tolerance. This provides an opportunity for the possibility of allowing plants to control their own bioproduction environments.

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This study was conducted to determine the effects of electrolyzed acid and alkaline solutions on the growth and quality of radish (Raphanus sativus L.) sprouts. The fresh and dry weights of the radish sprouts, the contents per 100 g FW and amounts per leaf of chlorophyll, and the contents per 100 g FW and amounts per plant of sugar, ascorbic acid and 4-methylthio-3-butenyl isothiocyanate (MTB-ITC) were analysed. The plants cultivated in 1⁄1 and 1⁄2 strength alkaline solutions exhibited superior growth and a low MTB-ITC content. With an increasing degree of dilution of the alkaline solutions, the growth was retarded, and the contents of chlorophyll, sugar, ascorbic acid and MTB-ITC increased. The amounts of these components were the highest in the 1⁄2 strength alkaline solution. The plants withered and died in the 1⁄1, 1⁄2 and 1⁄5 strength acid solutions. The growth of the plants and the contents and amounts of above components in the 1⁄10, 1⁄50 and 1⁄100 strength acid solutions were similar to those of plants grown in distilled water. Cultivation in acid solutions did not improve the growth and quality of the plants.

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We investigated the effects of photoperiods (6-, 9-, 12-, or 24-h) on the vegetative growth, flowering and fruiting of two Capsicum frutescens L. lines from the Bonin and Ryukyu islands in Japan and C. annuum cv. ‘Takanotsume’ (referred to as BON, RYU, and TK, respectively). BON, RYU, and TK plants had better vegetative growth as photoperiod lengthened; plants were taller, and the dry weight of shoots and roots was greater. The leaf area of TK was not affected by photoperiod, whereas the leaf areas of BON and RYU were smaller when grown under a 24-h photoperiod than under a 12-h photoperiod because leaf abscission occurred sooner under a 24-h photoperiod. TK also had better reproductive growth as the photoperiod lengthened; flowers and fruits were more numerous, the fresh and dry weights of fruits were greater, and the percentage of fruit set was higher. Under a 24-h photoperiod, however, the flower bud development of BON and RYU was initially not observed. BON finally flowered under a 24-h photoperiod, but RYU did not. These results suggest that BON and RYU responded photoperiods more strictly than TK and there may be various responses to photoperiods in flowering and fruiting among lines of C. frutescens.

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A simple method using a vacuum manifold for extracting soluble carbohydrates for analysis by high performance liquid chromatography (HPLC) from various tissues of ornamental plants was developed. Rose ‘Sonia’ petals were immersed in ethanol solution at 75°C for 20 min. Sorbitol was added to the extraction as an internal standard, and extractions were transferred to filter holders on a vacuum manifold, and the manifold was then decompressed. The filtrate was evaporated to dryness, and used for HPLC analysis. In comparison to soluble carbohydrate extraction by conventional homogenization extraction, few differences in soluble carbohydrate content were observed. Carbohydrate content in the remaining plant tissue was confirmed to be very low, indicating that soluble carbohydrates are effectively extracted by this procedure. Few differences in soluble carbohydrate content were observed among rose stem and leaves between the new method and a conventional method. Also, few differences in soluble carbohydrate content were observed among petals or sepals, stems and leaves in carnation, Delphinium and snapdragon, using either the new or conventional method. These findings suggest that the new method, which does not require homogenization, is a very simple method for the extraction of soluble carbohydrates from various organs of several ornamental plants.

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This study was conducted to determine the effects of air ion supply on the quality of commercial lettuce (Lactuca sativa L.) during storage. Using positive and negative air ion generators, experiments were designated as high, medium, and low air ion dosage treatments corresponding to 1.0×10⁶, 1.5×10⁵, and 8.0×10³ ions cm⁻³, respectively. At the low dosage of negative air ions, the water loss rate was significantly lower, and the chlorophyll content was significantly higher. No significant differences were observed in the ascorbic acid, saccharide, and organic acid contents among the air ion treatments. Exposure to different concentrations of positive and negative air ions did not appreciably affect the respiration rates in the leaves. Exposure to the low dosage of negative air ions seemed to have a positive effect on food preservation.

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The allelopathic potential of cucumber (Cucumis sativus L.) plants after their crop harvest was investigated. Aqueous methanol extracts inhibited the growth of shoots of cress (Lepidium sativum L.), alfalfa (Medicago sativa L.) and barnyardgrass (Echinochloa crus-galli (L.) Beauv). A potent growth inhibitory substance in the extract was isolated by chromatographic separation of silica gel and Sephadex columns, Sep-Pack cartridge and HPLC. At concentration of 3 μg mL⁻¹, this substance inhibited cress shoot growth by 23% of shoot growth of control plants. These results suggest that cucumber plants may contain at least one growth inhibitory substance, which may be released into the environment, either as exudates from living plant tissues or leachates from residues of the plants, and may act as allelochemicals to neighboring plants.

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