Eggplant (Solanum melongena L., cv. Senryounigou) plug transplants were grown for 17 days in a closed-type transplant production system at photosynthetic photon flux on the tray surface of 0, 100 and 350 μmol m^-2s^-1 on days 0-3, 4-6 and 7-16, respectively, air temperature of 30/ 20°C, (photoperiod/dark period) CO₂ concentration of 1000 μmol mol^-1 (photoperiod), relative humidity of 80/100% (photoperiod/dark period) and photoperiod of 16 h d^-1. The electric energy consumption per transplant was 0. 35 MJ (0. 1 kWh) and its cost was 1. 4-1. 5 Japanese Yen. The period required for transplant production was about 2 weeks shorter in the closed-type transplant production system than in the open-type transplant production system (i.e. the greenhouse). The amount of consumed water per tray area in the closed-type transplant production system would be reduced from 65. 8 to 12. 3 kg m^-2 by reusing dehumidified water for irrigation. These results show that the closed-type transplant production system is feasible for commercialization.

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Photosynthetic rate, relative growth rate and vitaminC contents were measured in lettuce cultivated under red and blue lasers and the results were compared with those cultivated under light emitting diodes (LED). It was found that lettuce grew fairly healthily under red laser diode (650 nm) and blue laser (442 nm) with R/B ratio 10. However, both photosynthetic rate and growth rate rather diminished compared with LED cases. As for vitaminC contents, the result was about the same as LED cases.

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A punching mechanism was developed for placing seeds of leaf vegetables directly into precut cells of urethane mat in hydroponic seedling production of leaf vegetables. The mechanism has twelve punchers, which are in the form of a hollow cone to penetrate into urethane mat for seed placement. The mechanism was attached and synchronized to the conventional vacuum seeder. When punchers penetrate the urethane mat, seeds are discharged from nozzles and delivered to punchers through tubes. Seeds of mustard spinach were used for the performance test. Punchers with outer diameter of 3.0 mm and cone index angle of 10 degrees could successfully penetrate into pre-cut cells of urethane mat. The punchers accurately placed the seeds at pre-determined punching depth of 3.0 mm with seeding efficiency of 96.5%.

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The concentration of dissolved oxygen in a culture solution is one of the most important environmental factors affecting the growth of the tops and roots of plants under hydroponic culture. In particular, the roots of tomatos readily absorb oxygen in the solution, and are thus sensitive to the concentration of dissolved oxygen. Thus, the effects of dissolved oxygen concentration on the morphology and growth of roots, water uptake rate and nutrient uptake were investigated. In hydroponic culture, the supply of dissolved oxygen is essential. Previously, we reported that supersaturation of dissolved oxygen in culture solution promoted the uptake of phosphate. In the present study, we found that supersaturation of dissolved oxygen in culture solution low in nitrogen and phosphate led to an increase in plant height, fresh weight of stems and leaves and root weight. It also increased the phosphorus concentration in the sap, stems, leaves and fruits of tomato plants.

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We have developed a new image analysis system, capable of quantitative analysis of two aspects of chlorophyll a fluorescence ; i) the changes in intensity of chlorophyll fluorescence during dark-light transitions by the induction method, and ii) the chlorophyll fluorescence quenching by the saturation pulse method. With this system we analyzed the effects of an herbicide on the photosynthetic activity of Phaseolus vulgaris L. leaves. Furthermore, stomatal conductance and assimilation rate were measured with a diffusion porometer.
Results showed that the photosynthetic injuries caused by the herbicide were detected by both fluorescence measurement methods. These injuries were also detected with the porometer as a decrease in stomatal conductance and assimilation rate. Information obtained by the induction method was effective for determining the site in the electron transport system which was damaged by the herbicide. The saturation pulse method could analyze the photosynthetic injuries more quantitatively than the induction method. However, the saturation pulse method required an evenly distributed high level of photosynthetic active radiation (PAR), which makes it difficult to apply to a large leaf area. In contrast, the induction method did not require such a high level of PAR for measurements, and was easier to use for a large leaf area. Consequently, simultaneous use of the saturation pulse method and the induction method enables detailed diagnosis of injuries of the photosynthetic system.

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To theoretically estimate the surviving clone number, a formula was constructed using the probability of characteristic expression (genetic parameter) and planting efficiency (environmental parameter).
In case of initial 6 clones planted for afforestation, the expected number of surviving clones was 0.43.5 with a 7090% expected survival probability at planting efficiency. For clonal comparison, it seemed necessary to have more than 4 clones and 80% expected survival probability at planting efficiency. In case of 80% expected survival probability at planting efficiency, more than 3 clones were needed to obtain less than 5% probability of annihilation. If the planted clones were annihilated under such conditions, it seemed unlikely that other clones would survive at the same site because it is conidered a species level problem not individual (clonal) survival issue.
Using 2 clones with less than 80% expected survival probability at planting efficiency resulted in less than 1 expected surviving clone (0.60.9) resulting in afforestation failure. The upper limit of the clone number (45) at planting was thought to depend upon the limits of nursery management in Akita prefecture.

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This study aims to develop a detecting device of missing seed for precision seeding system on hydroponic seedling production of leaf vegetables. In this seeding operation, seeds were planted by vacuum nozzles into pre-cut cells of urethane mat. It is important to detect whether the nozzles picked seeds or not for improving the seeding performance. Moreover the detection should be done automatically. The detecting device of missing seed using a digital pressure sensor was developed. Seeds of mustard spinach (Brassica rapa L. var. perviridis) and Chinese cabbage (Brassica rapa L. var. pekinensis) were used for the performance test of the detecting device. The detection level for setting the pressure sensor was determined and selected at 574 and 569 KPa to detect missing seed of mustard spinach and Chinese cabbage, respectively. The detecting device ould detect the missing seeds and compensate for the missing seeds without using any supplementary seeder. The average seeding efficiency was improved from 96. 5 to 99. 8% and from 97. 3 to 99. 6% for seeds of mustard spinach and Chinese cabbage, respectively. The number of missing cells per ten urethane mats was much reduced from 105 to 6 and from 81 to 12 for seeds of mustard spinach and Chinese cabbage, respectively.

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The forms of Fe introduced into spinach (Spinacia oleracia L., cv. Lead) and lettuce (Lactuca sativa L., cv. Red-fire) by soaking the roots in 100 mg L^-1 ammonium ferric citrate solution for 9 hours (spinach) or 6 hours (lettuce) and their changes during storage for 7 days were determined. After soaking, the Fe content in the leaf blade of spinach and in the leaf of lettuce were 9.9 times (8.23±1.03 mg/100 g FW) and 2.9 times (2.63±0.23 mg) higher than that of the control, respectively and no foliar injury appeared in either plant. The sum of the ratio of water-soluble Fe and exchangeable Fe contents (the amount capable of absorption by the human body via digestion) to total Fe content was about 60% in spinach and about 57% in lettuce. The contents of water-soluble, exchangeable, HCl-soluble, and HCl-insoluble Fe changed negligibly during the storage at 4°C. During the storage at 25°C, these contents hardly changed in spinach, whereas the content of the water-soluble Fe in lettuce slightly decreased.

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The effects of 2, 4-dichlorobenzoic acid (DCLBA) on the number of cucumbers (Cucumis sativus L.) harvested were evaluated by split-root system hydroponic culture. DCLBA (10μmol·liter^-1) in the nutrient solution severely damaged the roots by disrupting the integrity of epidermal cells, and remarkably inhibited the uptake of NO₃^-, H₂PO₄^- and ^Κ+ ions. As a result, DCLBA significantly inhibited the number of cucumbers harvested. Supplementation of the nutrient solution with activated charcoal in one side pot recovered the inhibition especially for the uptake of nutrients, and partly recovered the harvested fruit number per plant compared to that without charcaol. These results indicated that DCLBA affected the uptake of nutrients, and inhibited the growth of young fruit after adsorption from roots.

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This study investigated the effect of a culture medium immersed with a calcium-mixed Granite (Tetsuta Village, Okayama), which is an igneous rock composed mainly of silica and aluminum oxide on wheat embryo growth. Wheat embryos were grown in vitro using hyponex as the basic medium. The basic medium was prepared using purified water, purified water containing 1.5 g of rocks per test tube and spring water (Tetsuta Village, Okayama). The results are as follows :
The survival rates were low in purified water. The average leaf formation rates in purified water, purified water containing rocks, and spring water were 40, 50 and 60%, respectively. The longest root growth was observed in the medium prepared using spring water, but the shoot/root (weight) rate was highest in the medium prepared using purified water containing rocks and spring water. The degree of stoma openings in purified water, purified water containing rocks and spring water were 0.5-1.0, 2.0 and 3.0, respectively.

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