高垣 美智子

In order to increase the efficiency of nutrient utilization in solution culture systems, it is indispensable to understand how plants absorb nutrients. A series of experiments were conducted using hydroponic culture system in the first to third experiments and soil culture system in the fourth experiment in a greenhouse in Okinawa, Japan. In the first experiment, changes in NO3-N absorption were measured every three hours during a 24-hour period on 40 days after transplanting (DAT) in cucumber. In the second experiment, daytime and nighttime NO3-N absorption were measured from 45 to 48 DAT in five crops including cucumber. In the third experiment, NO3-N, NH4-N, and K absorption in daytime, nighttime and shaded conditions were determined from 30 to 34 DAT in bitter gourd, a substitute crop for cucumber, and water spinach. In the fourth experiment, daytime and nighttime (NH4)(2)SO4-N-15 absorption rates were measured from 9 to 12 DAT in cucumber. The results showed that daily NO3-N absorption in cucumber peaked twice, just before midday and again just after the nightfall. The corresponding fluctuation pattern was observed in all other tested crops, with 20-41% of the total absorption occurring at night. Absorption rate of 15N in cucumber cultivated in soil also increased in daytime and decreased at night, with the nighttime rate accounting for 39-40% of the daily total absorption. The average nighttime NO3-N, NH4-N, and K absorption percentages of the daily total before shading the plant were 34-35%, 49-51%, and 33-49%, respectively. During the shaded period, these nutrient absorption rates dramatically decreased, except for NH4-N which was not affected by shading. Across all experiments, 20-51% of total absorption took place at night, the majority of which may concentrate around the early nighttime. Furthermore, the absorption rates may be influenced by photosynthetic products.

© 2015 by the authors; licensee MDPI, Basel, Switzerland.In recent times, attention has been focused on the role of urban green spaces in promoting human health and well-being. However, there is a lack of evidence-based research on the physiological effects of walking in urban green areas. This study aimed to clarify the physiological and psychological effects of walking in urban parks during fall. Twenty-three males (mean age 22.3 ± 1.2 years) were instructed to walk predetermined 15-min courses in an urban park and in a nearby city area (control). Heart rate and heart rate variability were measured to assess physiological responses, and the semantic differential method, Profile of Mood States, and State-Trait Anxiety Inventory were used to measure psychological responses. We observed that walking in an urban park resulted in a significantly lower heart rate, higher parasympathetic nerve activity, and lower sympathetic nerve activity than walking through the city area. In subjective evaluations, participants were more “comfortable,” “natural,” “relaxed,” and “vigorous” after a walk in the urban park. Furthermore, they exhibited significantly lower levels of negative emotions and anxiety. These findings provide scientific evidence for the physiological and psychological relaxation effects of walking in urban parks during fall.

Some residents living in urban areas with little chance to grow plants outdoors have recently started enjoying indoor farming using a household plant factory with artificial light (PFAL) or micro-PFAL in Japan, Taiwan, and China and a few other Asian countries. In addition, mini-PFALs have been set up for various purposes at restaurants, cafés, shopping centers, schools, community centers, hospitals, etc. Such micro- and mini-PFALs and their networks could help bring new lifestyles related to local production for local consumption, food, health, ecology, the environment and the Internet to people living in urban areas. This chapter describes the characteristics, functions, and examples of micro- and mini-PFALs.

The Center for Environment, Health, and Field Sciences, Chiba University and the Japan Plant Factory Association are using five greenhouses (semi-closed system) with an environmental control system and three plant factories with artificial lighting (total 10,845m2) on the campus of Chiba University for research, education, and training. Annually, over 5000 people visit the facilities to learn about and understand plant factories. This education program on plant factories has been carried out since 2011 for the graduate school students of Chiba University and short-stay (70-90 days) students from sister universities. Intensive business forums on plant factories have been held since 2010, covering the information, science, business, and operation of plant factories. Intensive plant factory business workshops have been held on a wide range of issues for business people by planning workshops, excursions, and instructor dispatches on a monthly basis since 2009.

The physiological and psychological relaxation effects of viewing a kiwifruit (Actinidia deliciosa Hayward') orchard landscape were investigated. Seventeen Japanese adult females (46.1 +/- 8.2 years) viewed a kiwifruit orchard landscape or a building site (control) for 10 min. The heart rate variability and heart rate were determined. The modified semantic differential method and the short-form Profile of Mood States were used to assess the psychological effects. Compared with viewing the building site, viewing the kiwifruit orchard landscape resulted in a significant increase in the parasympathetic activity, a marginally significant decrease in the heart rate, a significant increase in comfortable, relaxed and natural feelings and a significant improvement in mood states.

Protected cultivation, especially in Asia, is operated at a small scale (<0.1 ha) using a relatively low-cost structure. This type of operation is a low-input, low-output system with low resource use efficiency, while larger industrial operations (>1 ha) with high-input, high-output systems that adopt modern high technologies have increased in number during the past few decades. In contrast, technology-intensive indoor agriculture operations (i.e., plant factories with artificial lighting or PFALs) in urban/suburban areas are steadily increasing in number. Such operations are a potential driving force for the development of resource-efficient technology to enhance the sustainability of both small- and large-scale protected cultivation. This paper focuses on recently developed controlled-environment technologies for these contrasting but technologically complementary applications. We discuss: A) low-cost intelligent environment controllers suitable for small-scale greenhouses; B) the concept and methodology of variable rate control; and C) closed plant production system (CPPS) and PFALs. Topic A includes intelligent controllers that can be used independently at a cost of around 100 Euro, and can also be used as a distributed environmental controller connected with an integrative environment control system for a large-scale greenhouse. Examples include controllers for: 1) null balance CO2 enrichment; 2) variable-rate fogging; and 3) multi-purpose heat pumps.

Background: It is widely believed that contact with the natural environment can improve physical and mental health. Urban green spaces may provide city residents with these benefits; however, there is a lack of empirical field research on the health benefits of urban parks. Methods: This field experiment was performed in May. Seventeen males aged 21.2 +/- 1.7 years (mean +/- standard deviation) were instructed to walk predetermined 15-minute courses in an urban park and a nearby city area (control). Heart rate and heart rate variability (HRV) were measured to assess physiological responses. The semantic differential (SD) method, Profile of Mood States (POMS), and State-Trait Anxiety Inventory (STAI) were used to measure psychological responses. Results: Heart rate was significantly lower while walking in the urban park than while walking in the city street. Furthermore, the urban park walk led to higher parasympathetic nervous activity and lower sympathetic nervous activity compared with the walk through the city street. Subjective evaluations were generally in accordance with physiological reactions, and significantly higher scores were observed for the 'comfortable', 'natural', and 'relaxed' parameters following the urban park walk. After the urban park walk, the score for the 'vigor' subscale of the POMS was significantly higher, whereas that for negative feelings such as 'tension-anxiety' and 'fatigue' was significantly lower. The score for the anxiety dimension of the STAI was also significantly lower after the urban park walk. Conclusions: Physiological and psychological results from this field experiment provide evidence for the physiological and psychological benefits of urban green spaces. A brief spring-time walk in an urban park shifted sympathetic/parasympathetic balance and improved mood state.

2014年優秀論文賞

Background: Interaction with nature has a relaxing effect on humans. Increasing attention has been focused on the therapeutic effects of urban green space; however, there is a lack of evidence-based field research. This study provided scientific evidence supporting the physiological and psychological effects of walking on young males in urban parks in winter. Findings: Subjects (13 males aged 22.5 +/- 3.1 years) were instructed to walk predetermined 15-minute courses in an urban park (test) and in the city area (control). Heart rate and heart rate variability (HRV) were measured to assess physiological responses. The semantic differential (SD) method, Profile of Mood States (POMS), and State-Trait Anxiety Inventory (STAI) were used to determine psychological responses. Heart rate was significantly lower and the natural logarithm of the high frequency component of HRV was significantly higher when walking through the urban park than through the city area. The results of three questionnaires indicated that walking in the urban park improved mood and decreased negative feelings and anxiety. Conclusions: Physiological and psychological data from this field experiment provide important scientific evidence regarding the health benefits of walking in an urban park. The results support the premise that walking in an urban park has relaxing effects even in winter.

2013年優秀論文賞

Net photosynthetic rate of whole-plant (P-n) can be used to estimate plant growth and CO2 use efficiency (CUE) in a 'closed system with artificial lighting' (CSAL). CUE is defined as the ratio of the canopy net photosynthetic rate in a CSAL to the CO2 supply rate. P-n can be estimated based on the CO2 balance in the CSAL if the air exchange rate is known. The air exchange rate is usually estimated using CO2 as a tracer gas, but this method cannot be applied in the presence of plants. We propose a method for estimating P-n in a CSAL based on the air exchange rate estimated using water vapour instead of CO2 as a tracer gas. In this study, a growth chamber was used as an experimental CSAL. The air exchange rate was defined as the number of air exchanges per hour (N), which is the ratio of the hourly exchanged air volume to the air volume of the CSAL. Firstly, N was estimated using water vapour (N-W) and CO2 (N-C) as tracer gases in the absence of plants. Then, P-n and CUE of the tomato plants were estimated using the proposed method. The results showed that N-W agreed well with N-C and P-n was accurately estimated by the proposed method. The estimated CUE decreased with increases in N and CO2 concentration inside the growth chamber. It was concluded that the method can be used to estimate P-n and CUE in a CSAL. (C) 2012 IAgrE. Published by Elsevier Ltd. All rights reserved.

Water spinach (Ipomoea aquatica Forsk; I. aquatica) of the green-stemmed type (green type) is widely consumed, but there also exists a red-stemmed variety (red type). In the present study, the antioxidant capacity of the red type was compared to that of the green type in carbon tetrachloride (CCl4)-treated mice. CCl4-induced thiobarbituric acid reactive substrate (TBARS) formation in the liver was significantly suppressed in mice fed 5% red-type I. aquatica, while the green type showed no effect. Hydrophobic oxygen radical absorbance capacity (H-ORAC(FL)) in the red type showed a lower level than that in the green type: however, lipophilic ORAC (L-ORAC(FL)) and total-ORAC(FL) levels were significantly higher in the red type than in the green type. alpha-Tocopherol, anthocyanidin/proanthocyanidin, and beta-carotene contents were all significantly higher in the red type than in the green type. These results suggest that the wild red-type I. aquatica contains certain lipophilic components that exert antioxidant capacities not only in vitro but also in vivo. Such effective components in the red type would be beneficial phytochemicals for suppressing several diseases related to oxidative stress.

It is well-known that major irrigation projects have a strong scale economy, handicapping irrigation development in sub-Saharan Africa (SSA) because of the difficulty in formulating large-scale projects. Using project-level investment cost and performance data of major and minor irrigation projects, this paper examines the causes of the economy of scale phenomenon. We find that strong scale economy exists not only for major but also for minor projects, i. e., small- and micro-scale, projects. This is largely because of the existence of indivisible overhead costs such as high-opportunity-cost human resources for planning, designing and engineering management and supervision. We also find that large differences between major and minor projects in the absolute level of overhead as well as construction costs creates a strong scale diseconomy and results in better performance of minor projects. The advantage of minor projects holds even when their higher risk associated with the water source is taken into consideration. We argue that there is an urgent need to promote irrigation development in SSA through developing minor projects, and to reduce the heavy burden of overhead costs by developing the capacity of human resources at the national, local and farmer levels in the fields of irrigation engineering, irrigation agronomy, institutional development, and micro water management technologies. © 2011 Springer Science+Business Media B.V.

アジアでは1960年代にはじまった「緑の革命」により、土地生産性が飛躍的に増加したが、サブサハラアフリカでは、長期間にわたり土地生産性が停滞している。近年、サブサハラアフリカに「緑の革命」をもたらす可能性のある作物としてコメが注目されている。その理由が新品種ネリカ（NERICA：New Rice for Africa）の開発である。本稿では、ネリカの特徴とサブサハラアフリカのネリカ普及状況を整理した。また、サブサハラアフリカでネリカの普及が最も進んでいるウガンダにおいて、その要因を調査した。その結果、ネリカは従来の品種に比べて有利な特徴があるものの多くの国で普及の初期段階にあること、農家によるネリカ採用には研修によって「ネリカについての十分かつ適切な情報を提供する」ことが重要であることが明らかになった。

窒素 (N) 肥料の施肥は東南アジアをはじめ様々な国において収入源の食糧生産を増加させるために重要である.収穫後に土壌中に多くの窒素が残存している場合, 硝酸態窒素による地下水汚染や亜酸化窒素 (N₂O) による大気汚染の原因となる.この研究の目的は3種類の緩効性N肥料が a) 葉物野菜の生長, b) 硝酸態窒素の表土 (0-20cm) からの溶脱, c) 土壌表面からのN₂O放出にそれぞれ与える影響を調査することである.プラスチック製のコンテナに畑土壌を充填し, コマツナ (Brassica campestrisL.) を栽培し, 以下の5つの試験区条件-CDU, UBF, UBM2, 尿素, 対照区 (無N肥料区) -をコンテナごとに与えた.3種類の緩効性N肥料と尿素はそれぞれ150kg N ha^-1の割合で施肥した.コマツナの生長測定項目とN吸収量はUBM2と尿素区で最も高かった.溶脱した硝酸態窒素量はUBM2とUBF区においてCDUと尿素区よりも有意に高かった.土壌からのN₂O放出量はCDU区において最も高く, 続いてUBF, UBM2, 尿素, 対照区の順であった.N利用効率はUBM2と尿素区において最も高かった.

タイ国カセサート大学カンペンセンキャンパス内の熱帯野菜研究所圃場に設置した16メッシュのネットハウス内において, 農薬施用量の低減を目的とした三種類の葉菜類の短期栽培における適正な化学肥料施用量と収穫日数を調査した.試験は10月から12月にかけて行い, 葉菜類として1) カイラン (Brassica oleracea var. alboglabra) , 2) パクチョイ (Brassica napa var. chinensis) 及び3) チンゲンサイ (Brassica chinensis var. chinensis) の3種類を供試した.葉菜類の短期栽培に対する窒素施用量の効果を, 生育と窒素利用効率により評価した.3種類の葉菜類を4水準の窒素施用量 (156, 312, 468and625kg ha^-1) 条件下で栽培した.生育と窒素利用効率の両方から判断した適正施用量は, 3種類の葉菜ともに156kg ha^-1であった.また, 最も効率的な収穫日数はカイランとパクチョイでは播種後35日, チンゲンサイでは播種後28日であった.短期栽培では, 窒素肥料の施用量を従来の水準より減らすことで, 生育を抑制することなく窒素利用効率を上げることが出来ることが確認された.

各種有機質資材を培地の容水量から 1) 高容水量培地 (>45%v/v) ; やし殻 (CC) , もみ殻くん炭 (RHC) , バガスチャコール (BGC) とピートモスおよび2) 低容水量培地 (<45%v/v) ; もみ殻 (RH) と落花生英くん炭 (PHC) の二つのグループに分け, 容水量の高い培地と低い培地を組み合わせ, CC: RH, CC: PHC, RHC: RH, RHC: PHC, BGC: RH, BGC: PHC, PM: RHおよびPM: PHC, をそれぞれ1: 1の比 (v/v) で均一に混合し, トウガラシおよびキュウリ育苗用培地としての可能性を明らかにするため, 市販の育苗用培養土 (COM) (セル培土: スミリン農産工業株式会社) と比較した.CC: RHおよびCC: PHCで育苗したトウガラシ苗では茎径, 草丈, 葉面積, 地上部および全体の乾物重がその他の有機質資材を混合した培地で育苗した苗と比較して大きくなった.さらに, CCを含む培地でトウガラシ苗では播種後42日目の生育調査ではいずれの測定項目もPMを含む培地およびCOMの値よりも等しいか大きくなった.PHCを含む培地で育苗したキュウリ苗においては, 茎径, 草丈, 葉面積, 地上部および全体の乾物重の値がRHを含む培地で育苗した苗の値よりも大きくなった.キュウリ苗では播種後30日目の生育調査ではCCを含む培地での各値とPMを含む培地での値がほぼ等しくなった.最終的にいずれの苗においても今回の供試培地では外見上の違いは見られなかった.熱帯地域でのコストや利用性を考慮するとCCを含む培地がピートモスの代替培地としてトウガラシおよびキュウリの育苗に効果的であると結論した.

サツマイモ (lpomoea batatas (L.) Lam., 品種ベニアズマ) の単節単葉を増殖体として用い, 栽植密度 (D) を225, 473, 840および1313m^-2として増殖および苗化した.育成した母株およびセル成型苗の生育量, およびそれらの育成に関わる電気エネルギ消費量を調べた.増殖サイクルは18日間, 苗化期間は15日間とした.実験期間中は気温30℃, 相対湿度75%, 光合成有効光量子束100/200/300μmolm^-2s^-1 (実験0-4/5-9/10日目以降) , 明期16hd^-1, CO₂濃度1000μmolmol^-1とした.育成実験で得られた測定値より, 数理モデルを用いてサイクルを繰り返した場合の増殖体生産数 (N _(n) , n: 繰り返し数) および苗あたりの電気エネルギ消費量 (E_{t (n)} ) を推定した.さらに, 苗の定植後の生育量も調べた.閉鎖型苗生産システム内のトレイの収容面積に制約が無く、トレイを置く場所が不足しない場合、サイクルの経過に伴うN _(n) の増大の割合はDが225m^-2のときに最大となった.一方, システム内のトレイの収容面積が、その最大値とした500m²に達した後は, Dが840m^-2のときにN _(n) が最大となった.E_{p (n)} は, システム内のトレイを収容する面積の制約の有無にかかわらずDが840m^-2のときに最小 (1.15MJ, 電力料金4.3～4.5円) となった.Dの増大とともに圃場に定植後の塊根収量は減少した.閉鎖型システムにおいて栄養繁殖による苗生産を効率的に行うためには, 短期間で増殖体生産数および苗当たりの電気エネルギ消費量を, Dなどを変数として, 適切に管理する方法を考案する必要がある.

New production system, reaping and regrowth system (RRS) using automatic reaping harvester and rail system, was developed for lettuce and some leaf vegetables. With this system labor saving and better efficiency of harvest works should be achieved in lettuce and some leaf vegetable production. Simultaneously the products harvested could be distributed directly as cut-vegetables and packing works also might be simplified. A rail system developed for tea plantation was introduced into the plastic house and set up along the cultivation bed. The harvesting system we used was automatic reaping harvester developed from the tea harvester moving on the railways. With this system, upper leaves could be reaped off at a specific height precisely, allowing the plants to redeveloping new leaves or shoots for successive harvest. Vegetable jute (Corchorus olitorius L.), sweet basil (Ocimum basilicum L.), leaf lettuce (Lactuca saliva L.) was cultivated under protected condition. The influences of the planting density and reaping height for each vegetable on the yield and quality of the produce were investigated. The efficiency of this harvest system was also evaluated as the time used for harvest. Higher yield was obtained with higher planting density and the time required for harvesting unit area of each vegetable with this system was markedly reduced in this system to 1/100 or less compared with conventional cultivation method. For leaf lettuce culture, reaping at 13 cm from the base resulted in higher yield. Total of 15 harvests of lettuce could be obtained with planting distance of 10 x 10 cm. We concluded RRS should be feasible for leaf vegetables with high harvest efficiency. Further research is needed on this system for application to other vegetables and produce sterilization and packaging works.

Two leaf vegetables, Pak Choi (Brassica campestris L. chinesis group) and Chinese kale (Brassica oleracea L.), were cultivated using a capillary hydroponics system in greenhouse. A reaping method was introduced for harvesting leaves to reduce labor and other costs. In this method, upper leaves or shoot were reaped off at a specific height, allowing the plants to regenerate new leaves or shoot for successive harvest. Seedlings were transplanted to the systems with 30 liters of 1/2 strength Enshi nutrient solution and leaves or shoot were harvested at a 3-cm height from surface of the substrate every 15 to 20 days for three times. For Pak Choi, average production rates (g FW/plant/d) showed no significant differences among three harvesting times and they were significantly higher than those of plants harvested conventionally. Reaping method can be applied for leafy vegetable production, and suitable duration or height of cutting needed to be investigated. Regardless of plant species, production rates during the second to the third harvest were greater with rice husk charcoal with rice husk top or coconut coir than with the other substrates. For cultivation longer than two months, rice husk charcoal with rice husk top and coconut coir were suitable. We concluded that the harvest method examined in the present study was feasible for leaf vegetable production based on the hydroponic systems.

地下水の過剰利用や地球環境の変化により, 旱害は農業生産において深刻な問題となりつつあることから, 乾燥条件下における植物生理の理解を深め, 乾燥ストレス耐性を付与した品種育成を目的とした研究が急務となっている. Capsicum annuum L.の中で, タイチリとニューエースは環境ストレスに対して対照的な反応を示す品種として知られていることから, この2品種を用いて乾燥ストレスに対する生理的反応を調査した.乾燥ストレス処理に際し, ヒートパルス法によるサップフロー, 気孔コンダクタンス, 葉の水ポテンシャルの測定を行った. タイチリは乾燥に対してより高い感受性を示し, 水分供給量が限られている場合に蒸散による余分な水分損失を押さえていると思われた.また, 潅水を再開した後の, サップフロー, 気孔コンダクタンス, 葉の水ポテンシャルの回復はタイチリの方がニューエースよりも早かった. さらに, 一度乾燥ストレス処理を受けた植物は二度目のストレス処理の際に, 以前に乾燥ストレスを受けていない植物よりも強い乾燥ストレス耐性を示した. 品種間における形態, 生理的な違い, つまり, 葉や根の構造, 及び, 乾燥に対する水ポテンシャル調整機能の違いが, 乾燥ストレスに対する反応の違いをもたらしたと考えられた.

播種後100日のトウガラシ属4品種を用いて, 屋外の人工気象室内を使用して, 夜温を一定 (22℃) として昼温 (6: 00～18: 00) を3段階 (37℃, 32℃, 27℃) に変えた処理を7日間与え, 昼温が相対生長速度, 純光合成速度および蒸散速度におよぼす影響を調査した.<BR>蒸散速度は, 昼温が高くなると大きくなった.純光合成速度は, 蒸散速度の変化と対応せず, 昼温と果実生長の両方の影響を受けていたと考えられた.<BR>昼温の変化に伴う相対生長速度の変化は, 品種により異なっていた.昼温が高くなったとき生殖生長と栄養生長のどちらに生長が偏るかは, 器官によるsink能の差異によっており, 果実の生育段階と大きさによる影響が最も大きかった.未成熟果実を付けた植物体では, 果実の小さな品種は栄養生長に偏り, 果実の大きな品種は果実の生長に偏った.