The purpose of this study is to investigate the relation which related studies have not made clear between the soil water qualities, the ground level and the distribution of Bruguiera gymnorrhiza and Rhizophora stylosa in the south-east coast of Iriomote Island in Okinawa Prefecture. The investigations were carried out on the distribution of B. gymnorrhiza and R. stylosa, the ground level and the soil water quality at the fringe that was chosen as the main object in this study to replace the riverine which related studies have focused on. As a result, a strong relation was observed between the distribution and the ground level. The ground level of the seaward edge of the range of R. stylosa stand showed 102±2cm, that of the border between R. stylosa stand and B. gymnorrhiza stand showed 133±1 cm and that of the landward edge of the range of B. gymnorrhiza stand showed 167±0 cm (0 cm is set to be the same as the datum line in Ishigaki Is. in 1990) . A strong relation was observed between the distribution and the soil water qualities, too. The soil water salinity from the depth of 60 cm of the seaward edge of the range of R. stylosa stand showed 31.5±1.6‰; that of the border between R. stylosa stand and B. gymnorrhiza stand showed 25.7±0.9‰; that of the landward edge of the range of B. gymnorrhiza stand showed 19.3±2.2‰. The soil water qualities were influenced by the fresh ground water from the landward side. Small stands of R. stylosa were found surrounded by the vegetation of B. gymnorrhiza. Judging from the ground level, B. gymnorrhiza must grow in those areas, but the soil water quality in those areas were suitable for R. stylosa. This suggests that the relation between the distribution and the soil water qualities is stronger than the other.

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A simple water-culture for leafy vegetable using controlled-release fertilizer and rockwool was tested in this study. The recommended application is N. 0.5g pot^-1 (plant^-1) with 70 day and 100 day types. The concentration of nitrate, phosphorus and potassium from the controlled-release fertilizers was sufficient for plant growth and each varied within the range of the standard culture solution (Enshi-shoho) . The fertilizers would be able to be used for water-culture methods which store nutrient solutions and they would be adequate for the double-cropping of leafy vegetables such as lettuce growing for about 40 days. However, it seems that the concentration of ammonium from the fertilizers was excessive and the concentrations of Ca and Mg would be insufficient for plant growth, though they never induced excess or deficiency symptoms.

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イチジク‘マスイドーフィン’の鉢植え挿し木個体を20/15℃または30/25℃ (昼/夜) とした制御温室内に置き, 毎年新梢伸長開始期から, それぞれに半数に50mMNaClを12週間かん水して3年間の生育を調査した.
本実験でイチジクは新梢伸長から果実の形成を行い休眠に至るまで, 約32週間を1周期として生育した.温度やNaClは発育の周期に影響を与えなかった.
30/25℃区個体は樹体の生長量に年次変動が大きく, 花芽形成や収穫果実数が少なかった.一方, 20/15℃区では樹体生長は比較的安定しており, 果実数も多かった.NaCl処理によって両温度区とも生育は抑制されたが, 1年目と2年目には花芽分化が促進された.また, 20/15℃区ではNaCl処理によって果実糖度がやや高まる傾向が見られた.
このことから, より低濃度のNaClを処理することによって樹体の強勢化を抑え, 着果を促進し, また高糖度果実を生産することが可能と思われた.

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鳥取県下の湖山および佐治地区においてニホンナシ‘二十世紀’の芽の休眠打破を予測するためのchill unitモデルを検討した.このモデルはchill unitが1200に達するまでは8℃以下の気温を休眠打破に最も有効と評価して計算を行うが, それ以降のchill unitの積算には-4.0℃以下の気温は効果が無いと評価するものである.このモデルは従来報告されているchill unitモデルよりニホンナシ‘二十世紀’の休眠打破の予測に有効であり, ‘二十世紀’の低温要求量は1400chill unitとみなされた.

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暗所で育てた4日齢のダイコン (品種宮重) 芽生えに於いて, 芽生えの下胚軸の光屈性反応を増加させる前照射処理の影響について調べた.芽生えの上方からの白色光照射による前処理は, その後の横方向からの白色光に対する光屈性二次正屈曲反応を増加させた.この前処理の光屈性反応に対する効果は, 前処理の時間とともに増加し3時間で飽和した.この前処理は, 芽生えの下胚軸に行ったときだけ光屈性反応を促進させ, 芽生えの先端部や子葉に行っても効果は無かった.以上の結果は, 光屈性反応を増加させるこの前処理の光は, 光屈性の反応器官である下胚軸自体で感受される事を示唆している.

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Carbon dioxide concentration profiles in a test tube-type tissue culture vessel containing a plantlet cultured on sugar free medium were measured during the photoperiod. The CO₂ concentration at 70 mm below the lid was higher than that at 5 mm below the lid, and it decreased linearly with increasing the distance from the lid. When the photosysnthetic photon flux density (PPFD) was set at 20, 50, 80 or 140μmol m^-2 s^-1, the CO₂ concentration at 70 mm below the lid was 263, 150, 96 or 91μmol mol^-1, respectively, under a CO₂ concentration of 360μmol mol^-1 outside the vessel and an air temperature of 25°C inside the vessel. The CO₂ concentration difference inside the vessel between at 5 and 70 mm below the lid was 70, 137, 179 or 185μmol mol^-1, respectively, under the four levels of PPFD. When the CO₂ concentration outside the vessel was maintained 130, 340, 870, 1 890 or 2 570μmol mol^-1, the CO₂ concentration at 70 mm below the lid was 91, 104, 171, 363 or 770μmol mol^-1, respectively, under a PPFD of 110μmol m^-2 s^-1 and an air temperature of 25°C inside the vessel. The CO₂ concentration difference between at 5 and 70 mm below the lid was 27, 147, 477, 1 002 and 1216μmol mol^-1, respectively, under the five levels of CO₂ concentration outside the vessel. These results show that the CO₂ diffusion resistance inside the vessel is high and thus the net photosynthetic rate of the plantlet is restricted by low CO₂ concentration near the plantlet.

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Mangrove trees grow under reductive soil conditions which is normally injurious to root growth. This study focused on discussing the mechanism of mangrove trees in adapting to soil conditions. In the forests of Rhizophora stylosa and Bruguiera gymnorrhiza which are developed along the coast and clearly distributed zonally, iron, manganese, sulfur, boron and tannins contained in the soil environment and leaves were analyzed. H₂S damage is alleviated by the fact that FeS₂ is formed by Fe²⁺ reacting with H₂S formed by the sulfate reduction. The quantity of FeS₂ was limited by the concentration of Fe²⁺ and SO₄-S in the soil water. However the concentration of Fe²⁺ was kept under except in landward sites. Thus we will assume that Fe²⁺ has eluted by the reductive effect of tannins. Otherwise the Fe²⁺ would be insufficient for forming FeS₂. The tannins have eluted with rather high concentrations to soil water from the roots at seaward sites, then Fe²⁺ and Mn²⁺ have eluted due to the tannins. At the seaward edge of R. stylosa the concentrations of Fe and Mn in leaves were high. Mn, especially, accumulated in high concentrations. The reason is that the reductive effect of tannins accumulated in high concentrations in leaves like Mn kept a balance with the oxidation effect of Mn. In addition, at the seaward edge of R. stylosa the concentrations of B in leaves were also high. The reason is that B is related to the formation of catechin that is one of the principal ingredients of the tannins. Thus we will assume that the tannins, Mn and B play important roles in adaptation under the reductive soil conditions. In addition, a change in the concentrations in leaves between R. stlosa and B. gymnorrhiza may limit the distribution.

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There is a simulator for analyzing the plant-environment system in the National Institute for Environmental Studies. This simulator is a wind tunnel with air conditioner, solar simulator and control unit of soil environment. Profile of air temperature and humidity are controlled automatically in the simulator but that of wind velocity was not. Wind tunnels in other research fields have also been in a similar situation. We have therefore developed an automatic control system of wind velocity profiles in the simulator, and then examined the performance of the system and its application.

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Characterizing mass and energy balance at a plug sheet consisting of plug seedlings and soil mix is essential for optimum control of soil-mix moisture in plug seedling production. Time courses of rates of net photosynthesis, evapotranspiration and sensible and latent heat transfers of a tomato plug sheet under artificial light and the volumetric percent water content of soil mix were estimated micrometeorologically using the measured data on CO₂ concentrations, dewpoint temperatures at two heights above the plug sheet and weight of the plug sheet measured with an electronic balance. The first watering was done at the start of measurements and the second watering 16 hours after the first watering. After the first watering, the volumetric percent water content of soil mix decreased with time. Sensible heat transfer rate increased, and evapotranspiration and latent heat transfer rates decreased with decreasing volumetric percent water content when it was lower than about 20%. Net photosynthetic rate decreased with decreasing volumetric percent water content when it was lower than about 12%. One to three hours after the second watering, all the rates returned to the levels at the start of measurement. The present method is useful for on-line monitoring of micrometeorological and water-stress status of the plug sheet and for automatic watering based upon the status.

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Water (or moisture) content of soil-mix in a plug tray with limited-volume can easily be changed by evapotranspiration from a plug sheet and watering. Thus, timing and the amount of watering are the most important skills in plug seedling production. An automatic watering system for controlling water content of soil-mix in a plug tray was developed. A tomato plug sheet consisting of plug seedlings, soil mix in a greenhouse was watered by the watering system. The weight of the plug sheet was measured continuously with an electronic balance. When the weight of the plug-sheet decreased to a lower-limit setpoint by evapotranspiration, a solenoid switch of the watering system with overhead mist spray nozzles was turned on, and the plug sheet was watered. When the weight of the plug-sheet increased to a higher-limit setpoint by watering, the solenoid switch of the watering system was turned off. Watering was conducted only during the daytime. In this way, the weight of the plug sheet was controlled accurately in a range between the lower- and higher-limit setpoints during the culture period.

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