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Spectrum conversion film (SCF) is a covering material that modifies incident solar spectrum to more-active wavelengths in photosynthesis. Due to its fluorescence property, the performance of SCF cannot be accurately evaluated in a conventional way for agricultural films. We proposed quantitative methods to evaluate the conversion performance of SCF and tested the plant responses. The performance of GR films [green light (500–600 nm) to red light (600–700 nm)] containing different concentrations of dye (40–3000 ppm) was tested in comparison to a transparent film (control). A method for estimating light emission was developed using a series of equations and values measured under artificial lighting. The spectral properties and photosynthetic rates of sweet pepper (Capsicum annuum L.) leaves covered with the GR film were measured using a solar simulator. The emission of GR film was detected using a spectroradiometer connected to an integrating sphere instead of using a spectrophotometer used in the conventional method. The transmittance of GR film and its change rate of transmitted photon flux densities at emission wavelength differed depending on the light source. The change rate calculated through the equations was constant within the target spectrum and could be used as a basis for conversion performance. The solar spectrum modified by the GR film caused to increase the red light reaching the leaves by 10.47% and thereby increased the photosynthetic rates by 15.41% compared to the control. The photosynthetic efficiency based on incident and absorbed photons under the GR film increased by 22.14% and 21.87%, respectively. These methods were proposed for quantifying spectral properties of SCF under the solar spectrum, confirming the application of solar simulator for photosynthetic evaluation. When used as a standard light source for SCF, a solar simulator provides indoor test conditions with a spectrum similar to solar radiation without long-term cultivation or a large-scale film test.

Hollow structural sections (HSSs) are highly efficient in resisting compression, torsion, and bending. Their high torsional rigidity generally eliminates lateral-torsional buckling (LTB), w...

A non-destructive analytical method to measure plant internal electrical conductivity (ECp) was developed to monitor plant responses to changes in environmental conditions. However, the relationship between ECp and plant physiological responses has not yet been established. The objective of the study was to evaluate the relationships among ECp, photosynthetic responses, and sap flow in paprika to monitor ECp in relation to changes in environmental conditions. High ECp levels were related to high photosynthetic rate, stomatal conductance, and transpiration rate. Sap flow in the plant was also associated with ECp with a correlation coefficient of 0.606. However, the sap flow reflected only water flux, while ECp was determined by both water and ion content in stems of paprika. The ECp was predicted using environmental factors including temperature, irradiation, and relative humidity. A comparison of measured and predicted ECps could be used to detect unusual cultivation conditions for paprika such as drought and high temperature. Plant responses to water shortage were reflected by lower ECp compared to the predicted value.

The measurement of xylem sap flow is essential to understanding plant physiology in agriculture. Advanced hydroponics, for instance, would require sap flow measurement to observe the plant reaction to environmental variables, such as sunlight, humidity, and soil water content. However, most conventional approaches for sap flow measurement have been limited to large woody plants. Plants grown in hydroponics, e.g., tomatoes and bell peppers, are smaller and softer, and can hardly survive the invasion of thick thermal probes for flow speed measurement. This report presents a microneedle thermal probe that can be implanted into a small plant for the measurement of sap flow through the xylem. A microscale single hot wire on a single probe is used to benefit from small-scale physics in a simple configuration. The single probe enables minimally invasive measurement with a small thermal impact on plant tissues. We show that the Granier method can be modified to use the single hot wire as a heater and a temperature sensor simultaneously. Tests with a tomato stem result in a universal calibration model that can be applied to the same species. We demonstrate routine measurements of sap flow in a greenhouse tomato tree over a month, opening up the possibility for production scale application. [2018–0006]

This study experimentally and analytically investigates an innovative double-HSS link (DHL) used as the active link in eccentrically braced frames (EBFs). Hollow structural sections (HSS) are mechanically efficient and are used in resisting compression, torsion, and bending. Their high torsional rigidity generally eliminates lateral-torsional buckling (LTB). As a result, the plastic rotational capacity and strength degradation rate are mainly governed by flange local buckling (FLB) and web local buckling (WLB). The proposed configuration consists of a double-HSS connected to braces or columns through a center gusset plate secured by flare-bevel groove welds. The advantages of the proposed configurations are: (1) They effectively reduce the width-thickness ratios (b/t) of the flanges by using two HSSs with much shorter flanges, which considerably increases the compactness thereby enabling a large rotational capacity. (2) They provide simple and practical connection details between the link and braces or columns. (3) Typically, double-HSS sections have an e/(Mp/Vp) ratio much larger than that of wide-flange sections due to the fact that double-HSS sections have four webs which significantly increase the shear capacity. Consequently, a DHL can yield in flexure even with a length similar to that of a wide-flange shear yielding link. This in turn eliminates the need for web stiffeners. (4) The welding requirement for DHLs is less than that of the conventional shear links since no stiffeners are required. (5) The overstrength factor due to strain hardening produced by flexural yielding links is generally less than that produced by shear yielding links leading to more economical designs for the elastic portion of the frame, and (6) the iteration design process is minimized by balancing the link length and rotational demand because of a single flexural yielding mode. Furthermore, experimental and analytical results indicated that the novel DHLs can sustain larger plastic rotations and meet AISC 341′s acceptance criterion for shear yielding links. In addition, DHLs can be potentially used in D-braced EBFs with links attached to columns because the link-to-column connection of DHL remains essentially elastic. DHLs can also be used as a replaceable link which is attached to the beam and column through bolted end plates.

The spectrum of light affects both the electrical energy consumption by plants and photosynthetic efficiency. In a plant factory, where light-emitting diodes (LEDs) serve as an alternative to solar light, the optimal spectrum of light should be carefully chosen to maximize the rate of photosynthesis and the electrical energy efficiency of the crop. The objectives of this study were to investigate the photosynthetic rate of different colored lettuces (reddish and green leaves), to quantify the spectral dependence of photosynthetic efficiency, and to optimize the LED spectrum for maximum canopy photosynthesis and electrical energy consumption in lettuce grown in a plant factory. Two lettuce cultivars (Lactuca sativa L.), ‘JeokChukMyeon’ and ‘CheongChukMyeon’, were assessed for light absorption and photosynthetic efficiency at the single leaf and canopy levels, and the relative consumption of electrical energy from the LED lights was measured at 18 narrow wavelength bands of 10 nm from 400 to 700 nm. Anthocyanin and chlorophyll content (SPAD value) were measured and correlated with leaf color. Light interception by the canopy was estimated with light transmittance models. The light absorption was similar among the green and reddish lettuce cultivars at most wavelengths, but slightly higher in the reddish leaves around 550 nm (green region). In the reddish leaves, photosynthetic rates per incident photon of a single leaf had two peaks at 650-660 and 400-410 nm, while the photosynthetic rate per absorbed photon had three peaks at 650-660, 400-410, and 540-560 nm. In the green region of the light spectrum, both photosynthetic rates per incident photon and those per absorbed photon were lower in the reddish cultivars than in the green cultivars. The spectral dependence of light absorption at the canopy level was much weaker than that at the single leaf level. The quantum yield and absorption of green light at the canopy level were nearly same as those of blue and red lights, indicating that the photosynthetic efficiency of green light at the canopy level was higher than that at the single leaf level. The relative electrical energy consumption was lower in the green region than in the red and blue regions. Therefore, the photosynthetic efficiency based on electrical energy consumption at the canopy level was much lower with green LEDs than with blue or red LEDs. These results describe the plant response to the light spectrum at the canopy level and can be useful for optimizing artificial lighting sources for maximum plant productivity and energy-savings in a plant factory.

The need for a very-long-span structure in sporting and industrial venues puts steel moment frames and braced frames at a disadvantage. In this regard, special truss moment frames (STMFs) c...

Interest in the life cycle assessment (LCA) methodology to determine the environmental performance of agricultural products has increased in recent years. However, the application of LCA is sometimes limited by the lack of accurate, precise, and complete inventory data. In this study, we reviewed publications related to the LCA of fresh tomato production in greenhouses to provide an overview of the inventory data and identify opportunities for a more complete assessment of the environmental impact of tomato production. Among the reviewed publications, thirty-six papers were chosen for in-depth investigation. Additionally, the inventory data from seventeen of them were rigorously investigated, analyzed, and classified to be applied in the LCA of greenhouse tomato production. The selected papers cover forty-three scenarios involving the production of fresh greenhouse tomatoes in various regions. This review underlines the variations in inventory data among the studies and highlights inventory inputs that are commonly not considered in most assessments. In addition, the tomato production datasets of the commercial database Ecoinvent are discussed, and a recommendation on the usage of this database is provided. It is expected that future LCAs will disclose their inventory data in greater detail to improve transparency and help stakeholders in forming a more complete and informed opinion regarding LCA inventory content and its results.

Plant growth and development strongly influenced by light quantity and its spectral composition. Young tomato plants were cultivated in growth cabinets under artificial light provided by red and blue light emitting diodes(LEDs) during 12 hours, then plants were exposed to monochromatic ultraviolet, blue, green and red lights as an end-of-day(EOD) treatment during 4 hours to study their effect on plant growth parameters. EOD lighting from various LEDs increased total fresh and dry weights as well as assimilation area compared to those in control. Blue light increased stem height, internode length and stem diameter. Monochromatic UV-A light reduced stem elongation, highly increased stomatal conductance. Compactness and health index of young tomato plants were increased in UV-A and red light treatments.

The ice plant (Mesembryanthemum crystallinum L.), a medicinal plant with well-known effects on retarding diabetes mellitus, is increasingly being produced in plant factories in Asia. The ice plant is a Crassulacean Acid Metabolism (CAM) plant, but performs C3 photosynthesis during the juvenile period. The objective of this study was to develop a photosynthetic model of ice plants growing under plant factory conditions. C3 photosynthesis was observed in juvenile plants in plant factory growth conditions and a conversion from C3 to CAM photosynthesis was observed under salt-stressed condition at an electrical conductivity (EC) of 6.0 dS·m-1. The light saturation and compensation points, determined by a regression analysis of C3 light curves for the ice plant leaves, were 609.4 and 53.2 μmol·m-2·s-1, respectively. The accuracy of the light response was compared between negative exponential and non-rectangular hyperbolic function models. The non-rectangular hyperbola was more accurate with complicated parameters while the negative exponential function was more practical with simple parameters in the light response curves. Measurement of net CO2 assimilation rate (A) and intercellular CO2 concentration (C i ) allowed construction of the A-Ci curve and regression analysis of this curve revealed the CO2 saturation and compensation points as 632.9 and 117.2 μmol·mol-1, respectively. A coupled photosynthetic model was developed for the simultaneous prediction of photosynthesis, stomatal conductance, transpiration, and temperature of the ice plant leaves. Sharkey’s regression method was used to determine the photosynthetic parameters of maximum carboxylation rate, the potential rate of electron transport, and the rate of triose phosphate utilization, which were 222.3, 234.9, and 13.0 μmol·m-2·s-1, respectively. The parameters of minimum stomatal conductance of water vapor at the light compensation point (b) and the empirical coefficient (m) for the sensitivity of stomatal conductance and relative humidity in the Ball, Woodrow and Berry model could be solved as b = 0.0487 and m = 0.0012 by linear regression analysis using the measured A-Ci values. Although the A-Ci curve of the negative exponential function had higher accuracy than the biochemical model, the coupled biochemical model could physiologically explain the photosynthesis of the ice plant leaves under plant factory conditions.

For the production of plants in controlled environments such as greenhouses and plant factories, crop modeling and simulations are effective tools for configuring the optimal growth environment. The objective of this study was to develop a coupled photosynthetic model of sweet basil (Ocimum basilicum L.) reflecting plant factory conditions. Light response curves were generated using photosynthetic models such as negative exponential, rectangular hyperbola, and non-rectangular hyperbola functions. The light saturation and compensation points determined by regression analysis of light curves using modified non-rectangular hyperbola function in sweet basil leaves were 545.3 and 26.5 µmol·m-2·s-1, respectively. The non-rectangular hyperbola was the most accurate with complicated parameters, whereas the negative exponential was more accurate than the rectangular hyperbola and could more easily acquire the parameters of the light response curves of sweet basil compared to the non-rectangular hyperbola. The CO2 saturation and compensation points determined by regression analysis of the A-Ci curve were 728.8 and 85.1 µmol·mol-1, respectively. A coupled biochemical model of photosynthesis was adopted to simultaneously predict the photosynthesis, stomatal conductance, transpiration, and temperature of sweet basil leaves. The photosynthetic parameters, maximum carboxylation rate, potential rate of electron transport, and rate of triose phosphate utilization determined by Sharkey’s regression method were 102.6, 117.7, and 7.4 µmol·m-2·s-1, respectively. Although the A-Ci regression curve of the negative exponential had higher accuracy than the biochemical model, the coupled biochemical model enable to physiologically explain the photosynthesis of sweet basil leaves.

Plant structure is a significant factor for influencing the light interception and photosynthesis of plants. The light interception on the plant surface can be analyzed by three-dimensional (3D) plant model and optical simulation, but its accuracy is directly affected by the structural accuracy of the 3D model. This study aims to analyze and compare the effect of the accuracy of 3D structural models on light interception and photosynthesis. 3D-scanned plant models with different structural accuracies were constructed, and the light interception and photosynthetic rate were analyzed at single leaf and whole-plant scales. When using a low accuracy model that lacked the fine structural details of the plant, it was overestimated in light interception and photosynthetic rate compared to the 3D-scanned model that has high structural accuracy. At the single leaf scale, the light interception was higher in the low-accuracy model than that in the 3D-scanned model due to self-shadings from higher curvature in the leaf surface. At the whole-plant scale, the light interception and the subsequent photosynthetic rate in the low-accuracy model were 18% and 45 to 58% higher than those in the 3D-scanned model at light intensities of 700–2000 μmol m−2 s−1 at the upper canopy. The 3D-scanned plant model could accurately estimate the light interception and photosynthetic rate of the plants through optical simulation. The presented methodology can contribute to accurate analyses of plant light environment, plant physiological response, and plant growth modelling.

Light is a major environmental factor affecting the regulation of secondary metabolites, such as pigments and flavor. The Solanaceae plant family has diverse patterns of fruit metabolisms that serve as suitable models to understand the molecular basis of its regulation across species. To investigate light-dependent regulation for fruit pigmentation and volatile flavors, major fruit pigments, their biosynthetic gene expression, and volatiles were analyzed in covered fruits of tomato and bell pepper. Immature covered fruits were found to be ivory in color and no chlorophyll was detected in both plants. The total carotenoid content was found to be reduced in ripe tomato and bell pepper under cover. Naringenin chalcone decreased more than 7-fold in ripe tomato and total flavonoids decreased about 10-fold in immature and ripe pepper fruit under light deficiency. Light positively impacts fruit pigmentation in tomato and bell pepper by regulating gene expression in carotenoid and flavonoid biosynthesis, especially phytoene synthase and chalcone synthase, respectively. Nineteen volatile flavors were detected, and seven of these exhibited light-dependent regulations for both ripe tomato and pepper. This study will help in improving fruit quality and aid future research works to understand the molecular mechanisms regulating the influence of light-dependency on pigments and flavor volatiles.

We addressed the question of whether it is useful to apply a titanium dioxide (TiO2) solution to promote the growth of strawberry plants in a greenhouse when they suffer from insufficient solar radiation during the winter season. A TiO2 solution was sprayed on strawberry plants three times during the growth period. This treatment occurred once on the 5th day of each month from December to February at concentrations of 50, 100 or 150 mg·kg -1. The control strawberry plants were treated with a foliar solution lacking TiO2. The length of the petiole was inhibited by TiO2 treatments, especially those in January and February. In terms of the fruits, the TiO2 applications were found to increase the yield and hardness of strawberries compared to the control. In addition, the contents of chlorophyll a and b in the leaves of the strawberries were increased by the treatment with TiO2 foliar spray. In contrast, the phenolic compounds of the fruits were decreased as a result of the TiO2 treatments. Combined, our results reveal that the application of TiO2 can promote the yield and quality of strawberry plants sufferings from a shortage of sunlight in a plastic greenhouse during the winter season.

In this study, geometrically nonlinear analysis of plate and shell structures is carried out by using a degenerated shell element. The present shell element is formulated by using the isogeometric concept. Reissner-Mindlin assumption is adopted in the element formulation where total Lagrange formulation is used. In particular, the positions of control points is consistently used to create the normal vector for the mapping between control points and associated points on real surface. The arc-length method is employed to handle the snap-through behaviour of shells. Several benchmark tests are tackled to verify the performance of the present shell element. From numerical tests, the present shell element can remove locking phenomena with the only use of refinement technique and it performs satisfactorily for both thin and thick plate and shell structures under geometrically nonlinear situations.

Three leaf vegetables, namely green lettuce, red lettuce (Lactuca sativa) and red-veined chicory (Cichorium intybus) were grown in minigreenhouses covered with two new functional films and conventional polyethylene film (PE). Seedlings of leaf vegetables were transplanted in a plastic troughs filled with soil-perlite mixture. Two functional films were made from polyolefin (PO) material. Measurement of optical characteristics showed that polyolefin films have better transmittance for the photosynthetic active radiation (PAR, 400-700nm) and higher absorptance for the ultraviolet radiation (UV, 300-400nm) in comparison with the conventional PE film. After three months of utilization higher loss in PAR transmittance was observed for conventional PE film. Leaf vegetables growth was enhanced and yield was increased in greenhouses covered by new functional films.

We examined the effect of two greenhouse covering materials (glass or solid polycarbonate sheets) on the light environment and growth of tomato and cucumber plants. Spectral analysis showed that polycarbonate sheets entirely blocked radiation in both the UV - B (300 - 320 ㎚) and UV - A (320 - 400 ㎚) ranges, whereas glass transmitted UV - A and was only opaque to UV - B. The transmittance of photosynthetically active radiation (400 - 700 ㎚) and near infrared radiation (700 - 1100 ㎚) was higher in polycarbonate than glass. Air and soil temperatures were not significantly different between greenhouses covered with either material. The growth of cucumber plants was slightly affected by covering materials, whereas no significant changes in growth parameters were observed for tomato plants. The color parameters of tomato fruits were affected by the cover material, whereas cucumber fruits showed similar coloration in both glass and polycarbonate greenhouses.

In this study, linear static analysis of continuum shell structures is conducted by using a degenerated shell element which is developed by using isogeometric approach. Notably, the present isogeomeric shell element uses the positions of control points to create the normal vector via the mapping between control points and associated points on real surface. A series of benchmark tests are performed to verify the performance of the present isogeometric degenerated shell element. From numerical test, the present shell element can overcome locking phenomena with only use of refinements and therefore any special treatment such as reduced integration, assumed strains, non-conforming modes are not required in the formulation.

Effect of 376 nm UV-A LED irradiation on the growth and morphology of tomato seedlings was studied. Tomato seedlings were grown under the 658 nm red LEDs or the red LED supplemented with two irradiation levels of the UV-A. The growth and development of tomato seedlings were significantly enhanced under the red light supplemented with the UV-A. Under the UV-A treatments, the tomato seedlings became more compact, the growth of plant organs was balanced, the leaf area was increased, and the total plant fresh and dry weights were also enhanced. Our findings suggested that the 376 nm UV-A from LEDs had a beneficial effect on the growth and development of tomato seedlings as similarly to the blue light.

Deficient insolation conditions (DICs) frequently occur during the winter and early spring season in Korea and negatively affect crop growth. This study was conducted to investigate changes in the yields and qualities of strawberry fruits under DICs that result from an insufficient input of sunlight. To induce DIC, strawberry plants were treated with 40 or 70% shading by covering the plants with curtains during growth in a plastic greenhouse. The shaded plants were cultivated from March to May of 2012. When the strawberry plants were subjected to the shading treatments, their photosynthesis and fruit yields were significantly reduced. Although the mineral element and organic acid contents of the fruits were not affected by the shading treatments, the total nitrogen (T-N) of the stems and roots were noticeably reduced. Furthermore, the shading treatments of the plants also resulted in reductions in the sugar contents and total phenolics of the fruits. In parallel with these observations, the shading treatments were also found to decrease the antioxidant activities of the fruits as measured with the DPPH assay. We suggest that the DIC-induced losses of strawberry fruit yield resulted from the reduced photosynthetic performances of the plants that were caused by insufficient sunlight.

A study on the static analysis of Timoshenko beams is presented. A beam element is developed by using isogeometric approach based on Timoshenko beam theory which allows the transverse shear deformation. The identification of transverse shear locking is conducted by three refinement schemes such as h-, p- and k-refinement and compared to other reference solutions. From numerical examples, the present beam element does not produce any shear locking in very thin beam situations even with full Gauss integration rule. Finally, the benchmark tests described in this study is provided as future reference solutions for Timoshenko beam problems based on isogeometric approach.

This experiment was conducted to investigate the effect of bed position and planting densities of watermelon grown on two-story bed on fruit quality in summer season (strawberry resting period). The width, length and height of a bed were 22, 102, and 13 cm and the medium in bed were used coir. Watermelon was treated in accordance with the bed position and planting density, one crop planting per one bed (A), upper bed (B) and lower bed (C) as one crop planting per one bed, upper bed (D) and lower bed (E) as two crop planting per one bed, respectively. Watermelons (Citrullus vulgaris Schard) were planted on two-story bed on May 8 and grown by drip irrigation

This study was conducted to elucidate the relationship between light and coloring and to obtain basic results for promoting redness expression in 'Kalle' (Pyrus communis L.) pear skin. It was investigated in location of anthocyanin layer by microscopic observation and differences in skin color expression of 'Kalle' bagged with paper bag which has different light transmittance rate and inside temperature. However, there was no anthocyanin layer in the brown skin and golden yellow color, anthocyanin layer was distributed in epidermins or hyperdermis of red skin pear and apple. Dark red colored 'Kalle' had more anthocyanin content, FW than light red colored apple 'Hongro'. Light transmittance rate of physical characteristics used paper bags was the highest in white paper bag, 42.2% and it also had more light quantity, than any other tested paper bags in specific wave length 650-655 nm. The maximum temperature of inner bag was higher about in yellow paper bag. The red coloration and anthocyanin contents in no bagged fruits were higher than in any other bagged fruit. However, red color expression among the bagged fruits was higher in white paper bag than in double layered black paper bag and yellow paper bag. Also, chromaticity value seemd to be a good index to explain variation of fruit skin color, because anthocyanin content and chromaticity value were higher. Based on these results, it is desirable to cultivate 'Kalle' without bag for stable redness expression but bagging is essential for decreasing damage by insect in Korea. Further examination to find suitable time of removing paperbag for redness expression and decreasing insect damage. In addition, it is required to develop paperbag whose transmittance rate is high in specific light wavelength or temperature of inner bags is low. Additional key words: anthocyanin, bagging, chromaticity value, light transmittance, Pyrus communis L.

A study on the free vibration analysis of Timoshenko beams is presented here. In order to determine natural frequencies of beams, a thick beam element is developed by using isogeometric approach based on Timoshenko beam theory which allows the transverse shear deformation and rotatory inertia effect. Three refinement schemes such as h -, p - and k -refinement are used in the analysis and the identification of shear locking is also conducted by using numerical examples. From numerical results, the present element can produce very accurate values of natural frequencies and the mode shapes due to exact definition of the geometry. With higher order basis functions, there is no shear locking phenomenon in very thin beam situations. Finally, the benchmark tests described in this study are provided as future reference solutions for Timoshenko beam vibration problem.