魯 娜

Grafted cucumber plants were grown in a new hydroponic system (“Kappa Land”, Mitsubishi Chemical Aqua Solutions, Co., Ltd., Tokyo, Japan). Two different nutrient management methods were applied to the plants as treatments: Electrical Conductivity-based Management (ECM) and Quantitative Nutrient Management (QNM). During the growth period, we examined plant growth characteristics and productivity, fruit growth characteristics and quality, and nutrient use characteristics. The results revealed that the QNM technique significantly reduced the nutrient supply rate per plant for Ca2+, SO42−, and N by 28.5%, 25.5%, and 23.3%, respectively. Similarly, the absorption rates per plant of SO42−, K+, and PO43− were reduced by 17.8%, 11.9%, and 10.9%, respectively. However, N, Ca2+, and Mg2+ absorption rates slightly increased in the QNM treatment. The nutrient wastes generated per kilogram of produced fruits were also reduced by 66.4%, 60.7%, and 30.2% for N, Ca2+, and SO42−, respectively. Although the QNM technique reduced the plant’s leaf area, it significantly increased its total length by 9.4%. The total and marketable yields were not significantly different between the ECM (9.0 and 8.0 kg plant−1) and QNM (9.1 and 8.2 kg plant−1) treatments. However, the QNM treatment produced the highest total dry matter of 617 g plant−1, surpassing the ECM treatment by 6.9%. On the other hand, differences in nutrient management methods did not significantly affect fruit quality, including total soluble solids, water content, skin color, size, and shape. These results suggest that with the QNM method, it is possible to produce quality cucumbers with high nutrient use efficiency while protecting the environment from nutrient wastes.

<title>Abstract</title>The color and nutritional quality of vegetables directly affect the choices of consumers and thus affect the commercial value of the vegetable products. Green light can penetrate the outer leaves and reach the inner leaves to promote photochemical reaction of the overlapping leaves of head vegetables. However, whether this promotion can increase the nutritional components and change the color of the inner leaves of head cabbages, which is one of the major head vegetables largely produced worldwide, remains unclear. Therefore, we investigated the changes in the colors and the concentrations of chlorophyll (Chl) and carotenoid of the inner leaves of two types of cabbages by externally irradiating the cabbage with green light. The results showed that a short-term (48 h) irradiation with low light intensity (50 μmol m⁻² s⁻¹) of green light enhanced the Chl concentration and colors of the inner leaves of cabbages, and the positive changes of these indicators increased as the leaf layers approached the head center of the cabbage. Simultaneously, we also establish a method to effectively estimate the Chl concentration using luminosity (<italic>L*</italic>) and greenness (<italic>− a*</italic>) when the Chl concentration is so low that it is difficult or not possible to be measured by SPAD meter. Our findings demonstrated that green light, as a new tool, can be used to control the colors and nutritional components of the inner leaves of cabbages. The discoveries will help produce head vegetables with the preferred phenotype desired by consumers using a plant factory with artificial lighting.

Nasturtium (Tropaeolum majus L.), as a medicinal plant, has a high phenolic content in its leaves and flowers. It is often used in salads as a dietary vegetable. Attracting strong demand, it could be a good candidate crop for a plant factory with artificial lighting (PFAL) that can achieve the mass production of high-quality crops with high productivity by regulating environmental conditions such as light. In this study, two experiments were conducted to investigate the effects of continuous lighting (CL) and different daily light integrals (DLIs) under CL on the growth, secondary metabolites, and light use efficiency (LUE) of nasturtium, all of which are essential in the successful cultivation in PFALs. In Experiment 1, two lighting models, the same DLI of 17.3 mol m-2 d-1 but different light periods (24 and 16 h) with different light intensities (200 and 300 µmol m−2 s−1, respectively), were applied to nasturtium. The results showed that leaf production, secondary metabolites, and LUE were higher under the 24-h CL treatment than under the 16-h non-CL treatment. In Experiment 2, three DLI levels (17.3, 25.9, and 34.6 mol m-2 d-1) under the CL condition were applied. The results showed that the growth parameters were positively correlated with the DLI levels under CL. The lowest DLI had the highest LUE. We conclude that the mass production of nasturtium under CL in PFALs is feasible, and the yield increases as DLI increases from 17.3 to 34.6 mol m-2 d-1 under CL without causing physiological stress on plants.

The issue of low tomato production in the tropics like Ghana has been a long-standing challenge. The advent of greenhouse technology has not significantly improved the yield of tomato compared to Japan and the Netherlands. Immediate technological interventions are needed. Through hydroponics, the low-node order pinching at a high-density planting system has been recommended in some studies. This system was intended to be established in Ghana, and it would be expected to improve the yield and fruit quality of tomato. In effect, a study was carried out in the greenhouse, at Chiba University using this system. A tropical tomato cultivar (Jaguar) was evaluated with Momotaro York at 3.8 m s2 and pinched at the fourth truss. Data collected were water and nutrient use efficiencies, plant growth rate, dry matter partitioning, and fruit yield and quality, as well as some physiological characteristics. The experiment was laid out in a randomized complete block design with three replications. Results showed that Jaguar cultivar was two times more efficient in water and nutrient use than Momotaro York at first harvest. Root tissue density recorded in Jaguar was significantly lower compared to Momotaro York. The net assimilation rate (NAR) recorded was markedly higher in Jaguar than Momotaro York at last harvest. All the physiological attributes recorded in both cultivars were not significantly different. Plant dry mass (DM) recorded was similar in the two cultivars; however, the DM partitioned to fruits was 55% in Jaguar compared to 46.5% DM for Momotaro York. Fruit yield per area did not differ in the two cultivars. Fruit yields of 28.8 and 30 kg m−2 per year were recorded in Jaguar and Momotaro York, respectively. In comparison, this yield result is 1.2–1.25 times less and 14.4–15 times higher than current tomato yields recorded in Japan (greenhouse) and Ghana, respectively. Fruit quality, in terms of total soluble solids recorded in Jaguar cultivar being 5.4 %Brix, was within the 3.5–5.6 %Brix recorded in Ghana. This system could effectively enhance the yield and quality of tomato in the tropics as well as economising on the use of resources.

Population growth and increased stress caused by urbanization have led to social problems that are predicted to intensify in the future. In these conditions, the recently established ”nature therapy” has revealed that an environment rich in various plant life significantly contributes to the relief of physical and mental stress. Meanwhile, from the perspective of reduction in the energy required for transportation and the retention of plant freshness, urban horticulture, in which plant life exists harmoniously with the city, has attracted considerable attention. Interactions between humans and plants in urban horticulture are considered to contribute to the good health and wellbeing of people. Therefore, we incorporate human-centered thinking based on nature therapy into horticultural produce-centered thinking based on conventional urban horticulture. By introducing a pioneering urban horticulture plant factory as an example, we propose the possibility of sustainable urban horticulture based on nature therapy.

The demand for high-nutrient and fresh vegetables, including coriander, has been growing rapidly. A plant factory with artificial lighting enables the application or suppression of stress conditions to plants for producing high-quality vegetables. This study aimed to determine a suitable root-zone temperature (RZT) treatment for enhancing the biomass and secondary metabolite content of hydroponic coriander plants. The combination of a mid-RZT (25 °C) pre-treatment with low (15 °C or 20 °C) or high (30 °C or 35 °C) RZT for a short period (3 or 6 days) was applied to the plants before harvesting. The fresh weights of the coriander plants were reduced under RZT stress. By contrast, the content of secondary metabolites, including ascorbic acid, carotenoids, phenolic compounds, chlorogenic acid, and the antioxidant capacity of the plants were enhanced by the combination of the lowest or highest RZT (15 °C or 35 °C) and the longer stress period (6 days). Growing coriander under an RZT of 30 °C for 6 days can produce large amounts of bioactive compounds and water, whereas growing coriander at an RZT of 15 °C for 6 days can produce high dry biomass and secondary metabolite content.

Grafting is a widely used technique, and graft compatibility between the rootstock and scion is a prerequisite for grafting. To date, the underlying causes of graft compatibility/incompatibility remain largely unknown. Here, using cucumber (Cucumis sativus L.) grafted onto pumpkin (Cucurbita L.) rootstocks with different degrees of graft compatibility, and both self-grafting and non-grafting as controls, an integrative analysis of mRNA and miRNA expression and regulatory networks was conducted by using RNA-Seq and sRNA-Seq at 25 days after grafting (DAG). A total of 223 differentially expressed genes (DEGs) and 30 differentially expressed miRNAs (DEMs) related to graft compatibility were identified based on their fold change. Using a combination of GO annotations and KEGG pathway data, the functional annotations and pathways of DEGs and DEM targets showed that a number of metabolic, physiological and hormonal responses are involved in graft compatibility in cucumber leaves including metabolic processes (e.g., “carbohydrate metabolic processes”), nutrient transport (e.g., “sugar transport”), signal transduction (e.g., “MAPK cascade”), plant hormone signal transduction (e.g., “abscisic acid-activated signaling pathway”), transcription factors (e.g., MYB, NAC and bHLH), oxidation-reduction processes, and defense responses. The results of our comprehensive analysis suggested that compatible rootstocks might possess a greater ability for cell proliferation and a more efficient carbohydrate metabolism that promotes plant growth. In contrast, incompatible grafts induced multiple defense response-related genes and various transcription factors, likely in response to stress. Additionally, they consumed large amounts of energy, which ultimately restrained the plants normal development. This study advances our understanding of the molecular mechanisms underlying plant graft compatible/incompatible responses and provides numerous mRNA and miRNA candidates for more in-depth studies into the graft compatibility process.

Background: High-temperature stress inhibited the growth of cucumber seedlings. Foliar spraying of 1.0 mmol·L-1 exogenous spermidine (Spd) to the sensitive cucumber cultivar 'Jinchun No. 2' grown at high-temperature (42 °C/32 °C) in an artificial climate box improved the high-temperature tolerance. Although there have been many reports on the response of microRNAs (miRNAs) to high-temperature stress, the mechanism by which exogenous Spd may mitigate the damage of high-temperature stress through miRNA-mediated regulation has not been studied. Results: To elucidate the regulation of miRNAs in response to exogenous Spd-mediated improvement of high-temperature tolerance, four small RNA libraries were constructed from cucumber leaves and sequenced: untreated-control (CW), Spd-treated (CS), high-temperature stress (HW), and Spd-treated and high-temperature stress (HS). As a result, 107 known miRNAs and 79 novel miRNAs were identified. Eight common differentially expressed miRNAs (miR156d-3p, miR170-5p, miR2275-5p, miR394a, miR479b, miR5077, miR5222 and miR6475) were observed in CS/CW, HW/CW, HS/CW and HS/HW comparison pairs, which were the first set of miRNAs that responded to not only high-temperature stress but also exogenous Spd in cucumber seedlings. Five of the eight miRNAs were predicted to target 107 potential genes. Gene function and pathway analyses highlighted the integral role that these miRNAs and target genes probably play in the improvement of the high-temperature tolerance of cucumber seedlings through exogenous Spd application. Conclusions: Our study identified the first set of miRNAs associated with the exogenous Spd-mediated improvement of high-temperature tolerance in cucumber seedlings. The results could help to promote further studies on the complex molecular mechanisms underlying high-temperature tolerance in cucumber and provide a theoretical basis for the high-quality and efficient cultivation of cucumber with high-temperature resistance.

Research and development on plant factory technologies has received increasing attention not only in the East, but also in Southeast Asia. Lighting technology using light-emitting-diodes (LEDs) of proper light spectrum improves plant production in a plant factory. What type of LED to be used for certain vegetables and whether it is economically feasible are two questions to be answered by the wide diffusion of the technology. This study intended to answer these questions by conducting an experiment wherein lettuce was grown in a plant factory using seven types of LED of different spectra. The experiment was conducted at Chiba University in Japan from January to March 2017. White LEDs could attain shoot-fresh-weight productivity, comparable to levels attained by fluorescent lamps. However, productivity varied greatly across different LEDs. High productivity LEDs had similar spectrum patterns in terms of percentage shares of photon flux density (PFD) of blue, green, red, and far-red lights, with red color taking about 50% of the entire PFD. At the current market price of lettuce, electricity, and LED lamps in Japan, the cost-performance of all the seven LEDs tested was above the break-even level, although there were large differences in performance between high and low productivity LED lamps.

The global demand for medicinal plants is increasing. The quality of plants grown outdoors, however, is difficult to control. Myriad environmental factors influence plant growth and directly impact biosynthetic pathways, thus affecting the secondary metabolism of bioactive compounds. Plant factories use artificial lighting to increase the quality of medicinal plants and stabilize production. Photosynthetic photon flux density (PPFD) and electrical conductivity (EC) of nutrient solutions are two important factors that substantially influence perilla (Perilla frutescens, Labiatae) plant growth and quality. To identify suitable levels of PPFD and EC for perilla plants grown in a plant factory, the growth, photosynthesis, and accumulation of secondary metabolites in red and green perilla plants were measured at PPFD values of 100, 200, and 300 mu mol m(-2) s(-1) in nutrient solutions with EC values of 1.0, 2.0, and 3.0 dS m(-1). The results showed significant interactive effects between PPFD and EC for both the fresh and dry weights of green perilla, but not for red perilla. The fresh and dry weights of shoots and leafy areas were affected more by EC than by PPFD in green perilla, whereas they were affected more by PPFD than by EC in red perilla. Leaf net photosynthetic rates were increased as PPFD increased in both perilla varieties, regardless of EC. The perillaldehyde concentration (mg g(-1)) in red perilla was unaffected by the treatments, but accumulation in plants (mg per plant) was significantly enhanced as the weight of dry leaves increased. Perillaldehyde concentrations in green perilla showed significant differences between combinations of the highest PPFD with the highest EC and the lowest PPFD with the lowest EC. Rosmarinic acid concentration (mg g(-1)) was increased in a combination of low EC and high PPFD conditions. Optimal cultivation conditions of red and green perilla in plant factory will be discussed in terms of plant growth and contents of medicinal ingredients.

<p>手賀沼の富栄養化水を利用したヨウサイの養液栽培で水路に沈殿するSSを造粒し，園芸培地として有効利用できるかを検討した．SS培地のNO₃-N含有量は市販培地に比べて極めて少なかったが，交換性Mnは非常に高い値を示した．培地を好気発酵処理すると，SS培地のNO₃-N含有量は発酵処理温度30°Cで処理前に比べて顕著に増加し，さらに処理中の培地の水分量が少ない程高い値を示した．交換性および水溶性Mn含有量は，SS培地の30°C処理では処理前よりも高くなった．一方，SS培地とバーク堆肥を混合することで交換性および水溶性Mn含有量が低下し，30°C処理でも処理後の水溶性Mn含有量の増加は認められなかった．45°C条件では培地の水分量にかかわらず，いずれの培地でもMn含有量が30 mg・kg^–1以下となった．30°C処理のSS培地では，コマツナの初期生育が抑制されたが，それ以外の処理区では，コマツナの生育の差は比較的小さかった．以上，SS培地で栽培したコマツナの生育は市販の園芸培土での生育に及ばなかったが，SS培地とバーク堆肥の混合物を好気発酵処理することによって化学性が改善するため，園芸培土として利用できる可能性があり，未利用資源の活用や富栄養化湖沼水の浄化の一助となると考えられた．</p>

Grafting using a pumpkin (Cucurbita sp.) rootstock is an effective way to improve cucumber (Cucumis sativus) resistance to a combination of chilling and salinity stresses. We evaluated the tolerance of 15 pumpkin cultivars to chilling, salinity, and combined stresses at the germination and seedling stages. Selected plant characteristics, including germination rate, germination potential, germination index, plant height, stem thickness, fresh weight, and dry weight, were analyzed. We used the unweighted pair group method with arithmetic mean for cluster analyses to determine the stress tolerance levels of the pumpkin cultivars. The 15 cultivars were divided into three clusters: tolerant, moderately tolerant, and susceptible to stress treatments. The stress tolerances of all cultivars were variable in the germination and seedling stages, and most cultivars were not tolerant to individual treatments of chilling or salinity stresses at both stages. These results suggest that identifying suitable cultivars for use as rootstock during cucumber grafting should involve the evaluation of stress tolerance during different growth stages. Additionally, cultivars tolerant to chilling stress may not be tolerant to salinity stress; therefore, the choice of pumpkin rootstock should depend on where the grafted plant will be grown. Cultivars tolerant to a combination of chilling and salinity stresses may be useful as rootstock for cucumber grafting. Our findings may serve as reference material for choosing appropriate pumpkin rootstocks for cucumber grafting.

Greenhouses with sophisticated environmental control systems, or so-called plant factories with solar light, enable growers to achieve high yields of produce with desirable qualities. In a greenhouse crop with high planting density, low photosynthetic photon flux density (PPFD) at the lower leaves tends to limit plant growth, especially in the winter when the solar altitude and PPFD at the canopy are low and day length is shorter than in summer. Therefore, providing supplemental lighting to the lower canopy can increase year-round productivity. However, supplemental lighting can be expensive. In some places, the cost of electricity is lower at night, but the effect of using supplemental light at night has not yet been examined. In this study, we examined the effects of supplemental LED inter-lighting (LED inter-lighting hereafter) during the daytime or nighttime on photosynthesis, growth, and yield of single-truss tomato plants both in winter and summer. We used LED inter-lighting modules with combined red and blue light to illuminate lower leaves right after the first anthesis. The PPFD of this light was 165 mu mol m(-2) s(-1) measured at 10 cm from the LED module. LED inter lighting was provided from 4:00 am to 4:00 pm for the daytime treatments and from 10:00 pm to 10:00 am for the nighttime treatments. Plants exposed only to solar light were used as controls. Daytime LED inter-lighting increased the photosynthetic capacity of middle and lower canopy leaves, which significantly increased yield by 27% in winter; however, photosynthetic capacity and yield were not significantly increased during summer. Nighttime LED inter-lighting increased photosynthetic capacity in both winter and summer, and yield increased by 24% in winter and 12% in summer. In addition, nighttime LED inter-lighting in winter significantly increased the total soluble solids and ascorbic acid content of the tomato fruits, by 20 and 25%, respectively. Use of nighttime LED inter-lighting was also more cost-effective than daytime inter-lighting. Thus, nighttime LED inter-lighting can effectively improve tomato plant growth and yield with lower energy cost compared with daytime both in summer.

Root zone high-temperature stress is a major factor limiting hydroponic plant growth during the high-temperature season. The effects of root zone cooling (SRP, 0.1 mM) on growth, leaf photosynthetic traits, and chlorophyll fluorescence characteristics of hydroponic Lactuca sativa L. grown in a high-temperature season (average temperature &gt; 30 degrees C) were examined. Both treatments significantly promoted plant growth and photosynthesis in the high-temperature season, but the mechanisms of photosynthesis improvement in the hydroponic grown lettuce plants were different between the RZC and SRP treatments. The former improved plant photosynthesis by increasing stoma conductance (G(s)) to enhance CO2 supply, thus promoting photosynthetic electron transport activity and phosphorylation, which improved the level of the photochemical efficiency of photosystem II (PSII), rather than enhancing CO2 assimilation efficiency. The latter improved plant photosynthesis by enhancing CO2 assimilation efficiency, rather than stomatal regulation. Combination of RZC and SRP significantly improved P-N of lettuce plants in a high temperature season by both improvement of G(s) to enhance CO2 supply and enhancement of CO2 assimilation. The enhancement of photosynthetic efficiency in both treatments was independent of altering light-harvesting or excessive energy dissipation.

In greenhouses during the winter season, a high vapor pressure deficit (VPD), particularly due to air exchange during midday period, can limit plant biomass and yield. Thus, the VPD control in greenhouses is of immense importance for cultivating plants. In the present study, the effects of VPD controlled by a fogging system on greenhouse environment and tomato plant growth were studied during a winter season. The VPD was effectively reduced by the fogging system from 1.4 to 0.8 kPa on average in the midday during the entire winter season. Maintaining a lower VPD in the midday increased tomato leaf stomatal index and stomatal conductance during the major part of the day, which led to increase in net photosynthetic rate. Furthermore, maintaining a lower VPD increased mean tomato biomass and yield by 17.3% and 12.3%, respectively. Thus, it is concluded that the VPD control via the fogging system promotes plant growth and productivity by improving photosynthesis during the winter season. (C) 2015 Elsevier B.V. All rights reserved.

To produce tomato fruits with 6% average Brix without decreasing yield, we investigated the effect of moderate salinity stress on Brix and yield in a single-truss, high-density tomato production system. Because tomato fruit development can be predicted from cumulative temperature, we also assessed cumulative temperature after anthesis as a potential indicator for determining the starting points of salinity stress treatments. When transverse diameters of the first fruit reached 4 cm (i.e., early increase treatment) or the first fruits were at the mature green stage (i.e., late increase treatment), nutrient solution electrical conductivity was slowly increased until the breaker stage from 1.8 dS.m(-1) to 6.0 dS.m(-1). Plants subjected to the late increase treatment produced tomato fruits with Brix values of 6% without reductions in marketable yield. We also increased nutrient solution electrical conductivity based on cumulative temperature after anthesis and found that early-treated plants produced tomatoes with higher Brix levels and yields than late-treated plants. In summary, moderate salinity stress to avoid excessive stress on plants increased sugar concentrations without decreasing fruit yield and resulted in tomato fruits with average Brix of about 6% when nutrient solution electrical conductivity was increased at a rate of 0.1 dS.m(-1).day(-1). Because seasonal differences in cumulative temperature influence the appropriate timing of salinity stress applications, further study is needed to optimize year-round growth under moderate salinity stress in single truss, high-density tomato production systems.

Light conditions are poor around the lower trusses of tomato plants in a low truss number, high plant density production system. We determined the effects of leaf rearrangements above the fruit trusses on fruit maturation and quality in tomato plants pinched above the third truss and cultivated under a high-density growing system. Integrated solar radiation at first and second fruit trusses and surface temperature of fruits at second fruit truss were increased in plants treated with leaf rearrangements above the trusses compared with those of the control, and the maturation of fruits at the third truss treated with leaf rearrangement was 4.6 days earlier than that of the control. The concentration of ascorbic acid (AsA) in fruits of plants treated with leaf rearrangement was higher than that of control fruits. However, leaf rearrangement had no effect on yield and Brix of the fruit. These results indicated that higher solar radiation together with leaf rearrangement promoted fruit maturation and increased AsA content in the fruit of lower trusses of tomato plants cultivated under a low truss number, high plant density growing system.

In the present study, we investigated the effects of supplemental lighting (SL) with white, red, and blue light-emitting diodes (LEDs) on the yield and quality of tomato grown under the single-truss tomato production system (STTPS). SL was applied for 28 days during the rapid fruit development stage. Based on the same power consumption, the light treatments with the white and red LEDs increased the fresh yield of tomato by 12 and 14%, and the dry yield by 16 and 14%, compared with the control (without SL), respectively. Based on the unit photons emitted, the white LEDs showed high efficiency as the red LEDs in increasing tomato yield, followed by the blue ones. The results were probably due to the white LEDs that contained more than 50% of green light characterized by high penetration into the canopy. The sugar and ascorbic acid contents were not affected by SL from the LEDs. These results indicated that the white and red LEDs were effective in enhancing tomato yield and, in particular, the white LEDs with a combination of red, blue, and abundent green light would be more suitable to the use of STTPS at a high plant density.

The single trass tomato production system (STTPS) was used to grow tomato plants at a density of 14.3 plants-irT2 for increasing the tomato yield in Japan. We applied supplemental lighting within the canopy at different tomato development stages to identify the most sensitive stage at which supplemental lighting will most effectively increase yield and quality of tomato fruits. Fluorescent lamps were used to supply intra-canopy lighting to tomato plants (5:00 21:00) during the stages of an thesis (stage 1), rapid fruit development (stage 2), fruit ripening (stage 3), and from initial anlhesis to red-ripe fruit (whole stage), respectively. Supplemental lighting applied to tomato plants during stage 2 and whole stage significantly increased the yield and sugar content of tomato fruits. Moreover, the contribution of supplemental lighting to the daily increase of tomato yield was highest at stage 2. The increase of fruit fresh weight and amount of supplemental lighting showed positive linear relationship. Supplemental lighting did not affect the ascorbic acid content of tomato fruits, fruit number per plant, and plant shoot weight among all the treatments. Thus, based on economic advantage, the use of supplemental lighting during the rapid fruit development stage of tomato plants under STTPS was most efficient.