後藤 英司

Artificial lighting is a merit of a 'plant factory', which might be utilized to suppress an increase in pest population. We investigated the effects of extending the light phase on diapause induction in the two-spotted spider mite (TSSM), Tetranychus urticae. TSSM were reared at 18°C under light phases ranging from 2 to 64 h combined with a constant dark phase of 16 h in aluminum bottles, with white light emitting diodes attached inside to minimize fluctuations in air temperature between the light and dark phases. Diapause was induced in adult TSSM females when the light phase was 24 h or shorter, and diapause induction was inhibited when the light phase extended over 32 h. The development of deutonymphs was delayed under a diapause-inducing photoperiod. Diapause inducing photoperiods may suppress an increase in the TSSM population, by slowing down development and reproduction. © 2007 Springer Science+Business Media B.V.

Hypericum perforatum L. (St. John's wort) is a traditional medicinal plant that is mainly used for the treatment of neurological disorders and depression. The present study was undertaken to investigate the effects of different light quality, including blue, white, and red light, in combination with two light intensities, 250 and 500 μmol m s photosynthetic photon flux (PPF) on the concentrations of medicinally important secondary metabolites in the leaf tissues and growth of H. perforatum plants. The results revealed that growth, was greatest in those plants grown under white and red light with 500 μmol m s PPF. The hypericin and pseudohypericin contents of the plants grown under red light with 250 μmol m s PPF were 1.9 and 1.9 times higher, respectively, than those grown under red light with 500 μmol m s PPF. The differences in contents between blue and white light treatment were not significant for plants grown with 250 μmol m s PPF. Our result revealed that the contents of medicinally important secondary metabolites in the tissues of H. perforatum plants can be altered by controlling the light environment. -2 -1 -2 -1 -2 -1 -2 -1 -2 -1

The validity of a developed control logic for operation a fog cooling system, was verified in a naturally ventilated greenhouse at durations of fog cooling system operation, cycles (t ) of 60, 120 and 240 s, then at constant duration of fog cooling system operation (t ) of 35 s. The capabilities of the proposed control logic were evaluated from the viewpoint of changes in dry bulb (or air) temperature (T ) and relative humidity (RH ) inside the greenhouse. Even when the t was changed, the control logic was capable of controlling the operation of the fog cooling system with appropriate t . Short t , would contribute to minimize not only changes in T and RH , but also foliage wetting. At a constant t , the control logic could lengthen duration of fog cooling system stand-by (t) that also prevented excessive fogging when the potential evaporation of sprayed water inside the greenhouse was low. The proposed control logic can be implemented for controlling the operation of a fog cooling system not only at constant U but also at constant U. f+s f di i f+s r r+1 di 1 r

In our previous study, it has been proved that photosynthetic abilities in leaves, e.g. maximum net photosynthetic rate, decreases with depth from the top of the year-round cultured tomato plant canopy in a large-scale greenhouse. In this study, we assessed the distribution of photosynthetic abilities within tomato plant canopy by measuring chlorophyll fluorescence parameter (F_v/F_m), SPAD value and chlorophyll concentrations and then investigated the relationships among these parameters. Maximum net photosynthetic rates in leaves within middle and lower layers decreased to half and seventh parts of that within upper layer, respectively. F_v/F_m significantly increased with depth in the canopy, however, SPAD value and chlorophyll a/b ratio significantly decreased with depth in the canopy. Low chlorophyll a/b ratio and high F_v/F_m in leaves within the lower layer suggested that these leaves acclimated to the low light condition and had high light-utilization efficiency for photosynthesis. These results indicated that the decreases in the photosynthetic abilities in leaves with depth in the tomato plant canopy are caused by the low-light acclimation. Furthermore, the correlations between chlorophyll a/b ratio and F_v/F_m, and SPAD value were observed. This result suggested that the measurements of F_v/F_m and SPAD value can be used as a rapid and concise tool to assess the photosynthetic abilities in leaves within tomato plant canopies.

In a greenhouse cooled by a fogging system, the fraction of fog that evaporates by absorbing sensible heat from the greenhouse air, β, is an essential parameter to be determined for evaluating the system performance. Recent studies estimated β under indoor conditions by collecting the non-evaporated fog that fell on a plastic sheet during a specified time and β was the difference between the amount of sprayed fog and the non-evaporated fog divided by the amount of sprayed fog. Using this method in the greenhouses causes an overestimation of β due to the evaporation of the fog that fell on the plant leaf/floor surfaces affected by solar and thermal radiation and the difficulty of collecting the non-evaporated fog that falls on the plant leaf surfaces. This paper presents a method for simulating β and for analyzing the fog evaporation based on the heat and water vapor balance of the greenhouse air. The conditions of the un-cooled air in the greenhouse were investigated to be used essentially in the simulation. An experiment to determine parameters for the simulation was conducted on a hot sunny day (August 9, 2004) in the Tokyo area to measure the environments inside and outside a naturally ventilated greenhouse with a floor area of 26 m . The greenhouse was cooled intermittently at a fogging rate of 10 g s for five different fogging durations (i.e., fogging time-interval time) of 1-3, 0.5-1.5, 1.5-4.5, 0.5-1 and 1-2 min, respectively. Evapo-transpiration rate of 150 potted tomato plants was estimated using reported correlations and the resulting values could be corrected based on the water vapor balance of the greenhouse air. The results showed that β had a certain pattern along with the fogging and interval time. The values of β estimated from the heat balance were identical to those estimated from the water vapor balance. The fogging duration of 1-3 min showed relatively high evaporation rate, in which, the integrated value of β over a working time of 41 min was 0.36. © 2005 Elsevier Ltd. All rights reserved. 2 -1

Background and Aims: Hypericum perforatum is a perennial herbaceous plant and an extract from this plant has a significant antidepressant effect when administered to humans. The plant is characterized by its secretory glands, also known as dark glands, which are mainly visible on leaves and flowers. The current study evaluates the influence of several environmental factors and developmental stages of the plant on the accumulation and synthesis of hypericin and pseudohypericin (Hy-G), the major bioactive constituents, in H. perforatum plants. Methods: The appearance of dark glands on different parts of the plant, under several environmental conditions, was monitored by microscopy. Hy-G concentrations were quantified by high-performance liquid chromatography. Key Results: A significant presence of dark glands accompanying the highest concentrations of Hy-G was observed in the stamen tissues more than in any other organ of H. perforatum. A linear relationship between the number of dark glands and net photosynthetic rate of the leaf and Hy-G concentration in the leaf tissue was also established. A very high concentration of Hy-G was measured in the dark-gland tissues, but in the tissues without any dark glands it was almost absent. The presence of emodin, a precursor of Hy-G, at a high concentration in the dark-gland tissues, and its absence in the surrounding tissues was also observed, suggesting that the site of biosynthesis of Hy-G is in the dark-gland cells. A significantly low concentration of Hy-G (occasionally non-detectable) was measured in the xylem sap of the stem tissues. The dark-gland tissues collected from leaves, stems or flowers contained similar concentrations of Hy-G. Conclusions: The concentration of Hy-G in various organs of H. perforatum plants is dependent on the number of dark glands, their size or area, not on the location of the dark glands on the plant. The study provides the first experimental evidence that Hy-G is synthesized and accumulates in dark glands. © The Author 2006. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved.

Temperature of the greenhouse cover T is an essential parameter needed for any analysis of energy transfer in the greenhouse. Measuring the correct value of T is difficult due to the transparency of the covering materials and the effects of solar and thermal radiation and air movement on the cover surface. Therefore, T , in most cases, has been estimated theoretically by applying an energy balance to the greenhouse. In this study, a simple measuring method was proposed to predict T using a thermocouple junction (copper constantan, type-T) adhered directly to the cover surface. A correction factor was provided in the form of a regression correlation to exclude the effect of solar and thermal radiation on the thermocouple junction. The effect of air movement on the junction was also examined for air current speeds up to 5 m s . The results showed that solar and thermal radiation have a significant effect on the junction temperature and resulted in an overestimation of T , while the air movement around the junction had no significant effect. This method, in addition to an infrared (IR) thermometer and a protected thermocouple junction with a passive radiation shield, was applied to measure the cover surface temperature of an experimental glasshouse under hot sunny and cloudy conditions. Protection of the thermocouple junction from solar and thermal radiation coming from the surroundings caused a large overestimation error in the measured value of T under sunny conditions. Values of T measured by the proposed method were in good agreement with those measured by the IR thermometer under cloudy and sunny conditions. The proposed method can be used to measure the greenhouse cover temperature or any surface temperature with a maximal error equal to the measuring accuracy of the IR thermometer (±1%). The different surfaces of the cover (side walls and roof) have almost the same temperature under any weather conditions. © 2006 IAgrE. c c c c c c c -1

St. John's wort (Hypericum perforatum L.) is a medicinal plant widely used for treatments of neurological disorders, depression, etc. Recently, studies have reported the production of St. John's wort plants under controlled environments with artificial light a promising technique to standardize and enhance the growth and medicinal contents. The present study investigated the effect of the light quality of fluorescent lamps on the growth of St. John's wort plants. The seedlings with 6-8 unfolded leaves were grown for 28 days under blue and red lamps in growth chambers under controlled environments. Dry weight of plants grown under the red lamps was greater compared with that of plants grown under the blue lamps.The CO₂ absorption rate of plants grown under the red lamps was similar to that under the blue lamps. Absorption of red light (600-700 nm) by leaves was lower than that of blue light (400-500 nm). Leaf area, number of unfolded leaves, number of branches from the main stem, and number of nodes of plants grown under the red lamps were greater than those of plants grown under the blue lamps. These findings demonstrated that the difference in dry weight of plants grown under these conditions was not due to the spectral characteristic or photosynthetic ability of leaves but due to the amount of light actually absorbed by the leaves. In conclusion, controlling the light quality can be an important technique for enhancing production of St. John's wort plants.

Fundamental studies were conducted to develop a facility having an adequate air circulation system for growing healthy plants over a long term under microgravity conditions in space. To clarify the effects of gravity on heat and gas exchanges between plant leaves and the ambient air, surface temperatures and net photosynthetic rates of barley leaves were evaluated at gravity levels of 0.01, 1.0, and 2.0 g for 20 sec each during parabolic airplane flights. Thermal images were captured using infrared thermography at an air temperature of 22°C, a relative humidity of 18%, and an irradiance of 260 W/m . The net photosynthetic rates were determined by means of a chamber method with an infrared gas analyzer at an air temperature of 20°C, a relative humidity of 50%, and photosynthetic photon fluxes (PPFDs) of 250 and 500 μmol/m /sec. Mean leaf temperatures increased by 1.9°C with decreasing gravity levels from 1.0 to 0.01 g and decreased by 0.6°C with increasing gravity levels from 1.0 to 2.0 g. The increase in leaf temperatures was greater at the regions closer to the leaf tip and at most 2.5°C over 20 sec as gravity decreased from 1.0 to 0.01 g. The net photosynthetic rate decreased by 20% with decreasing gravity levels from 1.0 to 0.01 g and increased by 10% with increasing gravity levels from 1.0 to 2.0 g at a PPFD of 500 μmol/m /sec. The heat and gas exchanges between leaves and the ambient air were suppressed more at the lower gravity levels. The retardation would be caused by heat and gas transfers with less heat convection. Restricted free air convection under microgravity conditions in space would limit plant growth by retarding heat and gas exchanges between leaves and the ambient air. © 2006 New York Academy of Sciences. 2 2 2

Engineering a life-support system for living on Mars requires the modeling of heat and mass transfer. This report describes the analysis of heat and mass transfer phenomena in a greenhouse dome, which is being designed as a pressurized life-support system for agricultural production on Mars. In this Martian greenhouse, solar energy will be converted into chemical energy in plant biomass. Agricultural products will be harvested for food and plant cultivation, and waste materials will be processed in a composting microbial ecosystem. Transpired water from plants will be condensed and recycled. In our thermal design and analysis for the Martian greenhouse, we addressed the question of whether temperature and pressure would be maintained in the appropriate range for humans as well as plants. Energy flow and material circulation should be controlled to provide an artificial ecological system on Mars. In our analysis, we assumed that the greenhouse would be maintained at a subatmospheric pressure under 1/3-G gravitational force with 1/2 solar light intensity on Earth. Convection of atmospheric gases will be induced inside the greenhouse, primarily by heating from sunlight. Microclimate (thermal and gas species structure) could be generated locally around plant bodies, which would affect gas transport. Potential effects of those environmental factors are discussed on the phenomena including plant growth and plant physiology and focusing on transport processes. Fire safety is a crucial issue and we evaluate its impact on the total gas pressure in the greenhouse dome. © 2006 New York Academy of Sciences.

The effects of blue light supplementation to red light on growth, morphology and N utilization in rice plants (Oryza sativa L. cv. Sasanishiki and Nipponbare) were investigated. Plants were grown under two light quality treatments, red light alone (R) or red light supplemented with blue light (RB; red/blue-light photosynthetic photon flux density [PPFD] ratio was 4/1), at 380 μmol m s PPFD. The biomass production of both cultivars grown under RB conditions was higher than that of plants grown under R conditions. This enhancement of biomass production was caused by an increase in the net assimilation rate (NAR). The higher NAR was associated with a higher leaf N content per leaf area at the whole-plant level, which was accompanied by higher contents of the key components of photosynthesis, including Rubisco and chlorophyll. In Sasanishiki, preferential biomass investment in leaf blades and expansion of wider and thinner leaves also contributed to the enhancement of biomass production. These morphological changes in the leaves were not observed in Nipponbare. Both the changes in physiological characteristics, including leaf photosynthesis, and the changes in morphological characteristics, including leaf development, contributed to the enhancement of biomass production under RB conditions, although the extent of these changes differed between the two cultivars. © 2006 Japanese Society of Soil Science and Plant Nutrition. -2 -1

An effective control logic for a high-pressure fog cooling system for a naturally ventilated greenhouse has been developed. A suitable duration of the fog cooling system operating time is estimated using weather data and the target relative humidity inside the greenhouse with a computational model based on mass and thermal balances of the greenhouse air. The program has three main tasks: (1) to read the dry bulb temperature set point inside the greenhouse for fogging system operation and the target relative humidity defined by the user; (2) to compute a suitable duration of the fog cooling system operation; and (3) to display relevant output information to the user. The duration of fog cooling system operation decreased as the water vapor pressure deficit inside the greenhouse decreased. The control logic of the fog cooling system would be used to lower dry bulb temperature by increasing the relative humidity to the target value. Our results prove that implementing this control logic for greenhouse fog cooling system is technically feasible.

For production of high-quality St. John's wort (Hypericum perforatum L.) transplants, several authors have proposed in vitro multiplication of a superior germplasm by clonal propagation followed by ex vitro acclimatization in the greenhouse with natural light. This ex vitro acclimatization is a vital stage for successful transplant production. However, few studies have attempted to determine the optimum conditions for ex vitro acclimatization under artificial light. The objective of the current study was to find the necessary duration of ex vitro acclimatization by gradually reducing relative humidity under controlled environments with artificial light for St. John's wort plantlets grown photomixotrophically (sugar-containing medium) and photoautotrophically (sugar-free medium) in vitro. The results showed that all photoautotrophically- and photomixotrophically-grown plantlets survived after the ex vitro acclimatization. Plantlets grown photoautotrophically in vitro were most suitable acclimatized to ex vitro environments by decreasing the relative humidity from 90 to 65% within two days. Meanwhile, the results suggested that plantlets grown photomixotrophically in vitro were most suitable acclimatized to ex vitro environments within four or seven days.

In rice plants grown under red light supplemented with blue light (red/blue-light PPFD ratio was 4/1), photosynthetic rates per unit leaf area measured under white light at 1,600 and 250 μmol m s were higher than those in the plants grown under red light alone. The higher photosynthetic rates were associated with higher total N content of leaves, which was accompanied by larger amounts of key components of photosynthesis-limiting processes, including Rubisco, Cyt f, ChI and LHCII. These results suggested that the increase in total N content of leaves induced by supplemental blue light enhanced both light-saturated and light-limited photosynthesis. -2 -1

We have developed a prototype of an execution system for plant growth simulation models using remote meteorological databases via the World Wide Web. A field lettuce growth model and a rice growth model were described in Java language and converted to server-side language (JavaServlet) programs executable on a Web server. The simulation programs were implemented on a Web server (Apache) with a Servlet engine (Tomcat). Plant physiological processes such as photosynthesis, respiration, translocation and aging were separated into different Java class files. Data input and output routines were described as versatile class files independent of plant growth models. Two classes acting as remote meteorological data agents were developed to access two meteorological data servers. One of the servers, MetBroker, was developed by the National Agriculture Research Center, Japan, and provides agricultural models with consistent access to 18 different online weather databases of several countries. The Ground Temperature Database System developed by The University of Tokyo, provides daily soil temperatures at 50 observation stations in Japan. The agent programs access these servers using RMI (Java Remote Method Invocation) and SQL (Structured Query Language) and acquire daily average, minimum and maximum air temperatures, daily sunshine duration and daily soil temperatures from those databases. The simulation programs could be executed without any problems in the system. Our system enables the client to execute a plant growth simulation on the Web server using various meteorological sources available on the Internet.

A fundamental study was conducted to develop a facility having an adequate air circulation system for growing healthy plants over a long-term under microgravity conditions in space. To clarify the effects of gravity on heat exchange between plant leaves and the ambient air, surface temperatures of sweet potato and barley leaves and replica leaves made of wet paper and copper were evaluated at gravity levels of 0.01, 1.0, 1.5 and 2.0 g for 20 s each during parabolic aeroplane flights. Thermal images were captured using infrared thermography at an air temperature of 26°C, a relative humidity of 18% and an irradiance of 260 W m . Mean leaf temperatures increased by 0.9-1.0°C with decreasing gravity levels from 1.0 to 0.01 g and decreased by 0.5°C with increasing gravity levels from 1.0 to 2.0 g. The increase in leaf temperatures was at most 1.9°C for sweet potato leaves over 20 s as gravity decreased from 1.0 to 0.01 g. The boundary layer conductance to sensible heat exchange decreased by 5% when the gravity decreased from 1.0 to 0.01 g at the air velocity of 0.2 m s . The decrease in the boundary layer conductance with decrease in the gravity levels was more significant in a lower air velocity. Heat exchange between leaves and the ambient air was more retarded at lower gravity levels because of less sensible and latent heat transfers with less heat convection. -2 -1

本研究では溶存酸素濃度を制御できる栽培実験装置を製作し, 溶存酸素濃度と養液温度を変えてホウレンソウの栽培実験を行った.その結果, 次のことが明らかになった.<BR>1) 液温25℃と30℃において, 過飽和濃度区の根重量は, 飽和区と比較して20%程度少ないにもかかわらず, 地上部乾物重は同程度であった.<BR>2) 液温25℃から30℃において, 正常に生育できる溶存酸素濃度の下限は2～7mg l^-1の間にある.<BR>3) 液温35℃において, 高溶存酸素濃度処理による高温障害の抑制効果はなかった.

The measurement of plant chlorophyll fluorescence has been used for many years as a method to monitor a plant's health status. These types of methods have been mostly relegated to the laboratory. The newly developed Relative Referencing Method allows for the measurement of chlorophyll fluorescence under artificial lighting conditions. The fluorescence signal can be determined by first taking a reference signal measurement, then a second measurement with an additional fluorescence excitation source. The first signal can then be subtracted from the second and the plant's chlorophyll fluorescence due to the second lighting source can be determined. With this simple approach, a photosynthesizing plant can be monitored to detect signs of water stress. Using this approach experiments on tomato plants have shown that it was possible to detect water stress, while the plants were continuously illuminated by fluorescent lamps. This method is a promising tool for the remote monitoring of crops grown in a CELSS-type application. Published by Elsevier Science Ltd on behalf of COSPAR.

Carbohydrate contents of Arabidopsis thaliana seeds during seed development under hypobaric conditions were examined in order to characterize the mechanism of low pressure-induced seed damage, and to determine critical pressures for seed development under low total and/or low oxygen partial pressures. We analyzed contents of starch, sucrose, glucose, and fructose in seeds at different developmental stages at 101 kPa total pressure with 21 kPa O partial pressure (control conditions), and at various low pressure conditions (23 kPa P /21 kPa pO , 101 kPa P /2 kPa pO , 53 kPa P /2 kPa pO , 23 kPa P /2 kPa pO , and 12 kPa P /2 kPa pO ). Our results indicate that maintaining an adequate oxygen partial pressure inside the siliques is necessary for seed production under hypobaric conditions. © Copyright 2003 SAE International. 2 tot 2 tot 2 tot 2 tot 2 tot 2

WWW(World Wide Web)上で動作する植物生育モデルの実行システムを開発し, 複数の生育モデルを用いてそのシステムを評価した。既存の多くの生育モデルのシミュレーションプログラムは, 高級言語またはシミュレーション言語で記述されている。各々のモデルは独自の計算アルゴリズムと複雑なサブルーチンを持つため, モデルのソースプログラムを別の言語に変換するのは難しい。そこで本システムでは, 開発された言語でシミュレーションを実行する方法を考案した。WWWサーバ上でクライアントとシミュレーションプログラム間のユーザインタフェースを構築し, 中間的な入出力ファイルを生成&middot;管理するCGI(Common Gateway Interface)プログラムをC言語で記述した。そしてシミュレーションプログラムを, CGIプログラムが生成する入力ファイルからデータを読み込み, 結果を出力ファイルへ出力するように修正した。この作業は簡単であり, シミュレーションプログラムの入出力ルーチンの修正にはソースプログラムを全部理解する必要がない。事例としてC言語で記述された露地レタス, Pascalによる水耕レタス, FortranとCSMPによる6作物の生育モデルのシミュレーションプログラムを対象に検討した。各プログラムの修正行数は20&sim;30行であり, 修正は容易だった。修正したプログラムをコンパイル後に本システムに実装し, WWW上で正常に動作することを確認した。

For the low cost vegetable transportation, the applicability of a low O₂ closed system was examined under ambient temperature. Heads of leaf lettuce grown under the controlled climate of a commercially operated plant factory individually placed in airtight containers filled with normal air or with low O₂ mixed gas (5% 0₂+95% N₂) were stored for 11 d and 13 d at 15&deg;C and for 7 d at 20&deg;C. Populations of mesophilic aerobic bacteria from levels of 10⁷ to 10⁹ CFU/g were detected at the end of storage on lettuce heads in control treatment (normal air). Contrary to this, final populations on lettuce heads in low O² treatment were 10²- to 10⁵-fold less than those in control treatment. As the final populations were less than 1 x 10⁷ CFU/g, leaves of lettuce heads in low O₂ treatment were not spoiled for all storage experiments. Supplementary examinations indicated that low O₂ treatment was not effective to suppress bacterial populations on lettuce heads having large populations as about the level of 10⁵ CFU/g or more at the beginning of storage. Hence, the low O₂ closed system can be applied exclusively to the leaf lettuce grown in plant factory that can normally assure small populations of bacteria. Adding to this bacterial point of view, cumulative quantity of CO₂ showed a reduction in respiration of lettuce head in low O₂ treatment. Moreover, large amount of ascorbic acid was lost in control treatment as compared to that in low O₂ treatment. However, no significant difference was observed in weight loss regardless of treatment.

This study examined the possibility of reducing the heat injury of spinach incurred by the roots. In the first experiment, spinach plants (Spinacia oleracea L. cv. Okame) were controlled or subjected to salt stress by adding 43mM NaCl to 30&deg;C nutrient solution for 11 days. In the second experiment, plants were grown in three different concentration of salt (control, 43mM, 130mM) or PEG (29gl^-1) treatments each for 2 days at 34&deg;C. In the first experiment, at 30&deg;C solution temperature, root weight of 43mM NaCl treatment was larger than that of control, while at 20&deg;C solution temperature, the weight was almost same between the treatments. In the second experiment, 43 mM NaCl treatment increased shoot and root weights compared to those of control. However, 130mM treatment as well as PEG treatment did not show any positive effect on growth. The results indicate that addition of 43mM NaCl could reduce the heat injury of spinach root under high nutrient solution temperatures.

Plant growth experiments were conducted to study the feasibility of growing plants under hypobaric condition. Seeds of rice and Arabidopsis thaliana germinated at 25 kPa total pressure with 5 or 10 kPa O partial pressures. Rice plants in vegetative stage grew normally at 50 kPa of total pressure with suitable O and CO partial pressures, however, their development in reproductive stage was delayed at 50 kPa total pressure. Seed production of Arabidopsis at 23 kPa total pressure with 21 kPa O partial pressure was almost the same as that at atmospheric pressure. Copyright © 2002 Society of Automotive Engineers, Inc. 2 2 2 2

To clarify the effects of gravity on heat/gas exchange between plant leaves and the ambient air, the leaf temperatures and net photosynthetic rates of plant leaves were evaluated at 0.01, 1.0, 1.5 and 2.0 G of 20 seconds each during a parabolic airplane flight. Thermal images of leaves were captured using infrared thermography at an air temperature of 26 °C, a relative humidity of 15 % and an irradiance of 260 W m . The net photosynthetic rates were determined by using a chamber method with an infrared gas analyzer at an air temperature of 20 °C, a relative humidity of 50 % and a photosynthetic photon flux of 0.5 mmol m s . The mean leaf temperature increased by 1 °C and the net photosynthetic rate decreased by 13 % with decreasing gravity levels from 1.0 to 0.01 G. The leaf temperature decreased by 0.5 °C and the net photosynthetic rate increased by 7 % with increasing gravity levels from 1.0 to 2.0 G. Heat/gas exchanges between leaves and the ambient air were more retarded at lower gravity levels. A restricted free air convection under microgravity conditions in space would limit plant growth by retarding heat and gas exchanges between leaves and the ambient air. -2 -2 -1

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.<BR>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.

Researchers from 5 Japanese universities have developed a plant growth facility (Space Plant Box) for seed to seed experiments under microgravity. The breadboard model of the Space Plant Box was fabricated by assembling subsystems developed for microgravity. The subsystems include air conditioning and water recycle system, air circulation system, water and nutrient delivery system, lighting system and plant monitoring system. The air conditioning and water recycle system is simply composed of a single heat exchanger, two fans and hydrophilic fibrous strings. The strings allow water movement from the cooler fin in the Cooling Box to root supporting materials in the Plant Growth Chamber driven by water potential deficit. Relative humidity in the Plant Growth Chamber can be changed over a wide range by controlling the ratio of latent heat exchange to sensible heat exchange on the cooling fin of the heat exchanger. The transpiration rate was successfully measured by circulating air inside the Plant Growth Chamber only. Most water was recycled and a small amount of water needed to be added from the outside. The simple, air conditioning and water recycle system for the Space Plant Box showed good performance through a barley (Hordeum vulgare L.) growth experiment. © 2001 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

As a part of a plant growth model retrieval system on the Internet, a model registration interface was developed to facilitate registration of new models in the retrieval system. Plant growth models were described in the retrieval system by a relational database with five tables. Two of the tables were 'Component' table and 'Effector' table. Components were important elements constituting the model and Effectors were factors that directly affect the Component. By introducing these two concepts, the retrieval system was able to search models that could give answers to the user's questions. However, introduction of Components and Effectors made registration of new models a hard and tedious work. To facilitate the registration work, the developed interface searched models from the model base that were similar to the new one, based on the key words which the model developer gave. The model developer modified one of the similar models thus found out to make it fit to the new model. In this way, registration of new models into the retrieval system was simplified.

For suction of water from a water supply vessel including both water and air under microgravity and g-jitter conditions, a water suction system using hydrophilic fibrous cloth was developed and its performance was evaluated at 0.01-0.02 g-realized for 20 s by parabolic flight in an aircraft. Vessels used for the experiment were glass flasks and had a suction port for suction filtration. A piece of hydrophilic fibrous cloth was arranged along the inner surface of the vessels and the end was fixed to the suction port of the vessels. In vessel without hydrophilic cloths and containing 220 mL of water, the water did not move more than 5 mm along the inner surface and did not reach the suction port under low gravity. When hydrophilic cloths were used, on the other hand, water gathered onto the cloth surface, moved up along the cloth and reached the suction port under low gravity. The amount of water sucked from vessels varied with the amount of water in the vessel and the sectional area of hydrophilic cloths. When the vessels including both water and air were flown during parabolic flight (10(-4) g), water in the vessel moved along the cloth and a water film was formed on the cloth. These results indicated that it is possible to suck water using the fibrous cloth suction system under low gravity and microgravity conditions. Under low gravity conditions, it was difficult to suck water only. However, it is not necessary to separate water from air when the system is used for supplying water to plant root medium consisting of both liquid and gas phases.

微小重力場植物実験装置のための湿度センサを選別するため, 一定湿度下で測定原理の異なる湿度センサの出力に及ぼす重力の影響を調べた。異なる重力は航空機を放物線状に飛行させることで実現した。その際, 内部の気温と気圧はほぼ一定に維持した (変動幅は, それぞれ0.6kPaおよび0.2℃以内であった)。重力は1Gから2G (30秒), 0.01～0.02Gの低重力 (20秒), 1.5G(30秒), 1Gと変化した。4つの高分子センサ, 1つのサーミスタセンサ, 1つの電解質センサを実験に用いた。相対湿度が58%と75%の湿り空気を, それぞれNaClとNaBrの飽和塩溶液を吸収させた高分子ポリマーを用いて容器内で実現した。6つのセンサを容積1Lの1つの容器内にすべて固定する場合と1つずつ容積10mLの容器内に個別に固定する場合で実験し, 実験中のセンサ出力を記録した。実験の結果, サーミスタセンサの出力のみ, 両湿度条件下で重力とともに変化し, 低重力下で最大, 2G下で最小であった。この変動は, 容器内空気の攪拌の有無によらず認められた。これは, 風速の影響を打ち消すための, センサ表面を保護しているフィルターによるためかもしれない。両方の気流攪拌条件下でフィルター内の気流拡散は, その強度が重力の強度によって影響される自然対流に支配されていたと考えられる。航空機内の気圧調整システムを作動する前には, このセンサ出力は圧力の影響を受けたが, このことは気圧がほぼ一定に維持されたパラボリックフライト中のセンサ出力の変化の原因とは考えられない。各センサを個別に容器内に固定した場合もサーミスタセンサの出力にのみ同様の変動傾向が認められ, 1つの容器内に全センサを固定した本実験での, センサ同士の相互影響については無視できると考えられる。以上のように, 重力変動に伴う気流拡散状態の変化が, サーミスタセンサの出力が重力に影響された原因と考えられた。

To study the effect of the space environment on plant growth including the reproductive growth and genetic aberration for a long-term plant life cycle, we have initiated development of a new type of facility for growing plants under microgravity conditions. The facility is constructed with subsystems for controlling environmental elements. In this paper, the concept of the facility design is outlined. Subsystems controlling air temperature, humidity, CO concentration, light and air circulation around plants and delivering recycled water and nutrients to roots are the major concerns. Plant experiments for developing the facility and future plant experiments with the completed facility are also overviewed. We intend to install this facility in the Japan Experiment Facility (JEM) boarded on the International Space Station. © 2000 COSPAR. Published by Elsevier Science Ltd. 2

The cooling effect of various kinds of greenery cover was investigated by both experimental model and computer simulation. Four concrete roof models were constructed and different coverings were arranged for each: bare concrete, soil layer, soil layer with turf, and soil layer with ivy. Temperature profiles, including air temperature in the air space under the roof were measured along with other environmental parameters to calculate the cooling effect. A computer model to simulate the systems and to evaluate cooling load was constructed using the simulation language CSMP. The simulated results matched reasonably well with the measured ones, and the cooling effect increased with increase in leaf area per unit roof area (LAI).

In this paper, existing nutrient uptake equations are evaluated for use in computer simulation to predict nutrient uptake in a hydroponic system. Most mechanistic nutrient uptake equations are based on either Michaelis-Menten kinetics, relative addition rate of nutrients, or plant nutrient demand.

Under 33 &deg;C high air temperature conditions in deep hydroponic culture, the effect of nutrient solution temperature on root activity was studied. Spinach plants (Spinacia oleracea L. cultivar 'Okame') were raised and their growth, soluble sugar content, and ion and water uptake were measured and analyzed. In the first experiment, the solution temperature of all treatments was initially set at 20 &deg;C, then raised to 20, 26, 30, and 34 &deg;C each for 3 days. When solution temperature was above 26 &deg;C, root growth was inhibited and sugar content increased. Thus for high nutrient solution temperature, there is a disturbance in the carbohydrate metabolism of the roots, which is a major factor in growth inhibition. In the second experiment, plants were grown in four different solution temperature treatments (20/20, 26/20, 30/20, and 34/20 &deg;C in light/dark periods) each for 12 days. The plants in the 30/20 &deg;C treatment had good ion uptake and root growth. The soluble sugar content also was the lowest of all of the treatments. This indicated that even if the solution temperature was raised to 30 &deg;C, the carbohydrate metabolism recovered due to the cooling of the solution during the dark period. The carbohydrate metabolism of the roots exposed to the 34 &deg;C treatment could not recover.

The simultaneous and discriminative measurement of the photosynthesis and the respiration of the plant was attained by simultaneous monitoring of CO and CO by artificial control of CO abundance of ambient air. The principle of the measurement is based on the following physiological processes. 6CO +12H O → C H O +6O +6H O 6 CO +12H O → C H O +6O +6H O 6CO + 12H O → C H O +6 O O+6H O Assuming that respiratory consumption of the new born carbon substrate fixed by photosynthesis is negligible during the measurement, the photosynthetic CO consumption and the respiratory CO production V̇ are measured according to the estimation (1) or (2), (1)for closed method, V̇ =k(V - V̇·t){Ḟ +(F /F )Ḟ } V̇ = k(V - V̇·t)( F -(F /F )F } (2) for open method, V̇ =kV̇ { (F - F ) + (F / F )(F -F )} V̇ =kV̇E { (F - F ) + (F / F )(F -F )} where V is initial volume of growth chamber including attached flexible bag, F is the inlet or initial gas concentration of CO and F is the ambient gas concentration of CO in the chamber, V̇ and V are the sampling rate of mass spectrometer and the ventilation rate of the growth chamber respectively, k is the STPD conversion factor = {273(P -P )/760(273+t )}, t (°C) is the ambient gas temperature. In the closed method, the gas container of the growth chamber is circulated, resulting F is varied according to the balance of consumption and production of CO , while in the open method V is controlled to keep F at a constant value. Both (1) and (2) methods were examined and evaluated on the measurements of komatsuna and maize. 13 12 13 13 13 18 18 18 13 12 13 13 12 12 13 13 13 13 12 13 13 13 13 13 12 13 13 13 2 2 2 2 2 6 12 6 2 2 2 2 6 12 6 2 2 2 2 6 12 6 2 2 2 RCO2 PCO2 0 CO 2 CO 2 CO 2 CO 2 RCO2 0 CO 2 CO 2 CO 2 CO 2 PCO2 E I CO 2 E CO 2 CO 2 CO 2 I CO 2 E CO 2 RCO2 I CO 2 E CO 2 CO 2 CO 2 I CO 2 E CO 2 0 ICO2 2 ECO2 2 E B H2O E E eco2 2 e eco2

A closed gas-exchange system was developed to measure gross photosynthesis and respiration discriminately and simultaneously. The system developed in this study included a high performance mass spectral analyzer for gas measurements. The gas-exchange system consisted of a 3L assimilation leaf chamber, a 1L flexible metallic bag, gas supply apparatus, and a lighting system. The lights were turned on and gas measurements were started after the initial CO concentration level was increased to 500 ppm. The CO gas was added to the chamber 10 min after the start of the light period. The lights were turned off 15 min after the addition of CO . The CO and CO concentrations in the chamber during the light and dark periods were measured for pothos and maize leaves. The CO absorption rate by the leaves was larger than that for CO during the light period. It was assumed that the CO absorbed by photosynthesis was not evoluted by respiration during the first 25 min from the start of the light period. Based on this assumption, gross photosynthetic rate and respiration rate were estimated by calculating the difference in uptake rates of CO and CO during the light period. 12 13 13 12 13 13 12 13 12 13 2 2 2 2 2 2 2 2 2 2

Lettuce (Lactuca sativa L., cv. Ostinata) growth experiments were carried out to study the effect of dissolved oxygen (DO) concentration on plant growth in a floating hydroponic system. Pure O and N gas were supplied to the hydroponic system for precise DO control. This system made it easy to increase the DO concentration beyond the maximum (or saturation) concentration possible when bubbling air into water. Eleven day old lettuce seedlings were grown for 24 days under various DO concentrations: sub-saturated, saturated, and super-saturated. There was no significant difference in fresh weight, shoot and root dry weights among the DO concentrations: 2.1 (25% of saturated at 24°C), 4.2 (50%), 8.4 (saturated), and 16.8 (200%) mg/L. The critical DO concentration for vigorous lettuce growth was considered to be lower than 2.1 mg/L. Neither root damage nor delay of shoot growth was observed at any of the studied DO concentrations. 2 2

Primed spinach (Spinacia oleracea L., cv. Nordic) seed was started in rockwool slabs in a growth room for eight days before the seedlings were transplanted into a controlled environment greenhouse equipped with five identical, but separate, NFT systems. The day and night temperatures in the greenhouse were maintained at 24 and 18°C, respectively, with the daytime starting at 06:00 and ending at 22:00 nr. A photoperiod of 16 hrs was maintained, to prevent early bolting, and different target daily integrated light levels (PPF, in mol m d ) were studied to observe dry weight production. HPS lamps were used as the supplemental light source. Thirty-three days after seeding a final harvest was performed. Using the expolinear growth equation, dry weight production can be predicted based solely on target daily integrated light levels. Total chlorine residuals in the nutrient solution higher than 1 ppm were observed to be toxic. Root disease (rot) in the plant crown was found to be caused by Fusarium. Several remedies, including three biofungicides and potassium silicate, were tried but none proved to be consistently successful. -2 -1

The effect of vapor pressure deficit (VPD) of air during photoperiod on spinach growth under low total pressure was examined. Spinach plants grown under atmospheric pressure were transplanted into a pressure-reduced growth chamber and cultured hydroponically for eight days. The air temperature in the growth chamber was kept at 25 °C during the light period and 20 °C during the dark period. In the control, the total pressure was 101 kPa and the VPD was 0.95 kPa. The low pressure treatment had a total pressure of 25 kPa and a VPD of 0.95 kPa. The low pressure and high humidity treatment had a total pressure of 25 kPa, and a VPD of 0.48 kPa. The VPD during the dark period was consistent for all treatments at 0.44 kPa. O and CO partial pressures were constant at 21 kPa and 40 Pa, respectively. The photosynthetic photon flux density (PPFD) on a plant bed inside the growth chamber was 250 umol m s on a plant bed. Relative growth rate (RGR) of spinach in the low pressure and high humidity treatment was significantly greater than in the control. There was no significant difference in RGR between the control and the low pressure treatment. The low pressure and high humidity treatment also had increased leaf area. These results showed that the effect of pressure alone was not significant on RGR, but the. combination of low pressure with high humidity was important. 2 2 -2 -1

A Linear Programming model has been constructed which aids in selecting appropriate crops for CELSS (Controlled Environment Life Support System) food production. A team of Controlled Environment Agriculture (CEA) faculty, staff, graduate students and invited experts representing more than a dozen disciplines, provided a wide range of expertise in developing the model and the crop production program. The model incorporates nutritional content and controlled-environment based production yields of carefully chosen crops into a framework where a crop mix can be constructed to suit the astronauts' needs. The crew's nutritional requirements can be adequately satisfied with only a few crops (assuming vitamin mineral supplements are provided) but this will not be satisfactory from a culinary standpoint. This model is flexible enough that taste and variety driven food choices can be built into the model. © 1995, All rights reserved.

An axis clinostat was constructed to create micro and negative gravity also a rotated flat disk was constructed with different rotation rates to give increased gravity, by centrifugal force up to 48g. Rice seeds were grown on agar in tubes at the constant air temperature of 20°C under an average light condition of 110 μmol/m /sec(PPF). Humidity was not controlled but was maintained above 90%. Since the tube containers were not large enough for long cultivation, shoot and root growth were observed every 12 hours until the sixth day from seeding. The lengths of shoots and roots for each individual plant were measured on the last day. The stem lengths were increased by microgravity but the root lengths were not. Under the negative gravity, negative orthogeotropism and under micro gravity, diageotropism was observed. No significant effect of increased gravity was observed on shoot and root growth. © 1995, All rights reserved. 2

The Ca accumulation in the leaves of lettuce was determined by Ca tracer measurements to study the effect of air supply to the inner leaves which were susceptible to tipburn, a Ca-related physiological disorder. Lettuce was exposed in a growth cabinet to various conditions of vapor pressure deficit (VPD), flow rate of air supply, and treatment time of air supply. Air was blown onto the inner developing leaves around a growing point. Without air supply in the light period, Ca accumulation in the outer leaves 7-10 cm in length increased with the increase in VPD in the cabinet air, while that in the inner leaves 1-3 cm long was not affected by VPD in the cabinet air and was extremely low. When air was supplied at a flow rate of 160 mL/min, Ca accumulation in the inner leaves was increased 4.6 times over that in the control. In the dark period, Ca accumulation increased in both the inner and the outer leaves when air was supplied. Air supply was shown to prevent tipburn by increasing Ca accumulation in the inner leaves, because it increased VPD in the air around the inner leaves, encouraged transpiration from the leaves, and consequently promoted Ca uptake from the root to the inner leaves. 45