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In this paper, the indoor environment of a small-scale high-density controlled environment agriculture (CEA-HD) space was simulated using computational fluid dynamics. Spatial modelling of the indoor environment considering the influential phenomena (e.g. transpiration and photosynthesis) over the indoor temperature, relative humidity, carbon dioxide (CO2) concentration, and airflow velocity is still challenging. These indoor environment conditions were computed for a 3D model of a CEA-HD experimental space while simultaneously modelling crop airflow impingement, transpiration and photosynthesis. The crops being grown were represented in the model as porous media zones and their exchanges with the indoor air were modelled using user defined functions. The air distribution parameters and configuration were optimized using a simplified 2D model to overcome the steep computational time, and associated cost, of 3D simulation. The objective function of the optimization problem relied on a correlation analysis of the simulation output. The optimization of the 2D model yielded an airfoil configuration that reduced the mean airflow speed and relative humidity variations between the cultivation tiers while achieving higher mean velocities (≈1.9 m⋅s-1) at a lower inlet speed (8 m⋅s-1). The proposed modelling and optimization approach is a small step forward towards model-based design and operation of CEA-HD production spaces. [ABSTRACT FROM AUTHOR]

Understanding the influence of light spectra on plant growth and antioxidant activities is crucial for optimizing cultivation practices and enhancing crop quality. In this study, we investigated the effects of different light treatments on growth parameters and antioxidant activities in five plant species: peppermint, Thai basil, cumin, lemon basil, and green holy basil. Our results revealed distinct responses to varying light spectra, with green light consistently promoting taller plant heights across all species. Additionally, blue light induced notable increases in plant width for certain species. Analysis of antioxidant activities demonstrated dynamic fluctuations in Total Phenolic Content (TPC) and Flavonoid Content (TFC) among different light treatments and plant species. While white and red light generally promoted higher TPC levels, blue light unexpectedly exhibited the highest TPC levels at specific time points. Moreover, investigation into DPPH Radical Scavenging activity revealed diverse temporal responses to light spectra, with blue light demonstrating exceptional activity at early stages and white and red light showing heightened activity at later time points. These findings underscore the importance of tailored light regimes in optimizing growth parameters and enhancing antioxidant activities in cultivated plants, thereby offering promising avenues for sustainable agriculture and food production practices. [ABSTRACT FROM AUTHOR]

Watermelon Jing xin No.4 and pumpkin Jingxinzhen No.4 were used as test materials, and LED pure white light was taken as control (CK). Five treatments were set, namely, red-blue light alternating at 1 hour interval (R/B1), red-blue mixed light (RB), red-blue light alternating at 6 hours interval (R/B6), pure blue light (B) and pure red light (R). Besides, experiments were carried out in a fully artificial light plant to delve into the optimal light formula for the growth and development of watermelon and Pumpkin seedlings. The results showed as follows: (1) the absolute growth rate of plant height, stem diameter and leaf area of watermelon seedlings under R/B6 treatment were increased by 77.2%, 110.7% and 68.5% compared with the control, respectively; the number of leaves of watermelon seedlings under R/B1 treatment was significantly increased by 78.6% compared with the control at 40d (P<0.05). Under R/B1 treatment, the absolute growth rate of pumpkin seedling height and the number of leaves at 40d after planting were significantly increased by 211% and 18% (P<0.05), respectively, and the absolute growth rate of stem diameter was increased by 85%. (2) The crude polysaccharide content of watermelon and pumpkin seedlings under R treatment was increased by 25.5% and 13.4% compared with the control (P<0.05), and the crude protein content of watermelon seedlings under B treatment was increased by 9.4% compared with the control, and the chlorophyll content of watermelon and pumpkin seedlings under RB treatment was higher than that under the control 10 to 40 days after planting. Watermelon and pumpkin seedlings treated with RB showed a 1.8% and 0.3% increase in chlorophyll content, respectively, on the 40th day after planting, compared to control plants. (3) At 40th day after implantation, PIabs of watermelon seedlings under B and R/B6 treatments were 2.8 times and 1.1 times higher than that of control, respectively. Pumpkin seedlings treated with R/B1 and R/B6 had 110% times and 34% higher PIabs, respectively, than control seedlings. In summary, alternating irradiation of watermelon and pumpkin seedlings with red and blue light effectively improved the growth and development of watermelon and pumpkin seedlings and enhanced the chlorophyll fluorescence performance, while blue light can increased the crude protein content and red light can increase the crude polysaccharide content. Thus, when watermelon and pumpkin seedlings are cultured in a uniform manner, alternating red and blue light can maximize the seedling quality and provide high-quality seedlings for factory production [ABSTRACT FROM AUTHOR]

To intelligently remove the yellow-rotten leaf of hydroponic lettuce, a new leaf removal method was proposed. The lettuce position was adjusted for yellow-rotten leaf removal according to the visual recognition and localisation, and then the adsorbed yellow-rotten leaf was lifted by air pipes. Finally, the leaf was clamped and removed along the flipping-tearing-twisting trajectory. The adsorbing pressure, adsorbing position, and clamping position for yellow-rotten leaf removal were confirmed by the adsorbing and stretching tests. To improve the leaf removal success rate, the tearing angle, flipping angle, and torsional time radio were optimised by Box-Behnken tests. A quadratic model for the three factors and leaf removal success rate was established to analyse the orders of significance, and the order of significance for single factor was (i) the tearing angle, (ii) the flipping angle, and (iii) the torsional time radio. The order of significance for interaction terms was (i) the flipping angle and tearing angle, and (ii) the flipping angle and torsional time ratio. The solved optimal combination of factors was a flipping angle of 100.5°, a tearing angle of 131.0°, and a torsional time ratio of 0.68, which gave the maximum leaf removal success rate. The optimal combination of factors was verified, and the leaf removal process was shot by high speed camera. The verification tests showed that the maximum leaf removal success rate was 82.8%, and the leaf removal process took 6.58 s, meeting the requirements of yellow-rotten leaf removal for hydroponic lettuce. • A new yellow-rotten leaf removal method is proposed. • The adsorbed yellow-rotten leaf is lifted by the air pipes and the clamped leaf is removed. • A flipping-tearing-twisting trajectory is used. • The optimised combination of key trajectory factors is verified by tests. [ABSTRACT FROM AUTHOR]

[Objective] The biological effects of red light (R) and far-red light (FR) on growth and quality of lettuce were studied to provide support for lettuce cultivation in plant factories. [Method] Lettuce (Lactuca sativa L. cv. Italian) was used as the experimental material, and light treatments lasted for 28 days. The light intensity was 250 μmol/ (m-2•s) and white light was used as the control (CK) . Various R/FR ratios of 0. 2, 0. 4, 0. 8, 1. 6, and 3. 2 were set to analyze the effects on growth traits of lettuce (plant height, fresh mass, dry mass, and leaf area) and the optimal R/FR ratio was determined. Then, different irradiation durations (14, 21, and 28 days) were set under the optimal R/FR ratio. The first two treatments were switched to white light after 14 and 21 days till the end of experiments at day 28. Furthermore, the effects of different irradiation durations on growth traits of lettuce were analyzed, and the optimum R/FR irradiation duration was screened. Finally, the photosynthetic characteristics (light response curve, CO2 response curve, net photosynthesis rate (Pn), intercellular CO2 concentration (Ci), stomatal conductance (Gs), transpiration rate (Tr), chlorophyll a, Chlorophyll b, carotenoids, and total chlorophyll content), quality parameters (soluble sugar content, soluble protein content, and ascorbic acid content), and activity levels of antioxidant enzymes (SOD, POD, and CAT) of lettuce were analyzed under optimal R/FR ratio and irradiation duration. [Result] With the increase of R/FR ratio, plant height decreased by 50. 57% to 111. 49%, fresh mass decreased by 6. 03% to 21. 19%, dry mass decreased by 2. 70% to 23. 11%, and leaf area decreased by 1. 84% to 9. 77% compared to CK. When R/FR ratio was 1. 6, total fresh mass was significantly higher than that in CK and the treatment with R/FR ratio of 3. 2, but without significant diffe-rences with other treatments. With optimal R/FR ratio of 1. 6, radiation duration of 14 days greatly improved fresh mass, with 30. 26%, 4. 40%, and 22. 94% increases compared with those of 0, 21, and 28 days, respectively. Compared with CK, the optimal R/FR ratio and irradiation duration significantly promoted the accumulation of fresh mass, soluble sugar, and ascorbic acid of lettuce, significantly reduced net photosynthetic rate (Pn), chlorophyll a, chlorophyll b, total chlorophyll, soluble protein, and carotenoid, as well as antioxidant enzyme activities. There was no significant difference in intercellular CO2 concentration (Ci), stomatal conductance (Gs), and transpiration rate (Tr) . Light response curve and CO2 response curve showed that photosynthetic rate (Pn) decreased significantly when light intensity was higher than 200 μmol/ (m-2•s) or intercellular CO2 concentration (Ci) was higher than 50 μmol/mol. [Conclusion] The R/FR ratio of 1. 6 and irradiation time of 14 days were recommended for lettuce cultivation in plant factories. This light environment could significantly improve yield and contents of soluble sugar and ascorbic acid in lettuce. [ABSTRACT FROM AUTHOR]

Abstract Understanding the influence of light spectra on plant growth and antioxidant activities is crucial for optimizing cultivation practices and enhancing crop quality. In this study, we investigated the effects of different light treatments on growth parameters and antioxidant activities in five plant species: peppermint, Thai basil, cumin, lemon basil, and green holy basil. Our results revealed distinct responses to varying light spectra, with green light consistently promoting taller plant heights across all species. Additionally, blue light induced notable increases in plant width for certain species. Analysis of antioxidant activities demonstrated dynamic fluctuations in Total Phenolic Content (TPC) and Flavonoid Content (TFC) among different light treatments and plant species. While white and red light generally promoted higher TPC levels, blue light unexpectedly exhibited the highest TPC levels at specific time points. Moreover, investigation into DPPH Radical Scavenging activity revealed diverse temporal responses to light spectra, with blue light demonstrating exceptional activity at early stages and white and red light showing heightened activity at later time points. These findings underscore the importance of tailored light regimes in optimizing growth parameters and enhancing antioxidant activities in cultivated plants, thereby offering promising avenues for sustainable agriculture and food production practices.

Root morphology, an important determinant of nutrient absorption and plant growth, can adapt to various growth environments to promote survival. Solution flow under hydroponic conditions provides a mechanical stimulus, triggering adaptive biological responses, including altered root morphology and enhanced root growth and surface area to facilitate nutrient absorption. To clarify these mechanisms, we applied untargeted metabolomics technology, detecting 1737 substances in lettuce root samples under different flow rates, including 17 common differential metabolites. The abscisic acid metabolic pathway product dihydrophaseic acid and the amino and nucleotide sugar metabolism factor N-acetyl-d-mannosamine suggest that nutrient solution flow rate affects root organic acid and sugar metabolism to regulate root growth. Spatial metabolomics analysis of the most stressed root bases revealed significantly enriched Kyoto Encyclopedia of Genes and Genomes pathways: "biosynthesis of cofactors" and "amino sugar and nucleotide sugar metabolism". Colocalization analysis of pathway metabolites revealed a flow-dependent spatial distribution, with higher flavin mononucleotide, adenosine-5′-diphosphate, hydrogenobyrinic acid, and D-glucosamine 6-phosphate under flow conditions, the latter two showing downstream-side enrichment. In contrast, phosphoenolpyruvate, 1-phospho-alpha-D-galacturonic acid, 3-hydroxyanthranilic acid, and N-acetyl-D-galactosamine were more abundant under no-flow conditions, with the latter two concentrated on the upstream side. As metabolite distribution is associated with function, observing their spatial distribution in the basal roots will provide a more comprehensive understanding of how metabolites influence plant morphology and response to environmental changes than what is currently available in the literature. [ABSTRACT FROM AUTHOR]

Artificial light sources in plant factories offer numerous advantages over traditional plant production. Optimal artificial l ighting systems will provide sufficient light to promote plant growth. Thus, this study aimed to determine different artificial light sources on plant growth, especially on internode length, root length, potassium (K), Calcium (Ca), and magnesium (Mg) contents of green oak lettuce (Lactuca sativa L.). Three artificial light sources were utilized in the plant factory: a fluorescent lamp (FL) typically used in plant factories and two light-emitting diodes (LED): bulb-LED and bar-LED lamps. Alternate periods of 12 h of light and dark were applied to the used factories. The results indicated that the lettuce grown under bulb-LED irradiation exhibited the lowest internode length and highest root length of green oak lettuce, regardless to light intensity and the higher photos ynthetic photon flux density (PPFD) values of bulb-LED at the growing stage. K, Ca, and Mg contents in the lettuce shoot decreased in the order of K > Ca > Mg for all artificial light sources. The highest K, Ca, and Mg contents were 14.77±3.08, 4.77±0.92 and 108.14±9.36 mg/g dried weight (DW) obtained in lettuce grown under FL irradiation. Lower FL light intensity promotes nutrient deficiency, resulting in increased plant uptake. There was no significant difference in nutrient content betwe en plants grown with bulb-LED and bar-LED. The K/Ca and K/Mg mole ratios were lowest in plants grown under FL irradiation. These findings suggest that FL can be used to control lettuce nutrient levels, whereas bulb-LED can be used to control lettuce growth. [ABSTRACT FROM AUTHOR]

Although the plant factory (PF) industry is expanding worldwide, there are currently no regulatory measures for wastewater discharged from PFs in South Korea. This study aims to present the characteristics of major pollutants discharged from PFs that have not been reported in the literature and suggest effective management measures for them. The occurrence of 17 pollutants in hydroponic wastewater (HW) from 33 PFs was analyzed, and their potential ecological risk (PER) to aquatic life was assessed. Water samples were collected up to three times from each PF. The detection frequencies of 11 pollutants, including total organic carbon, total nitrogen, total phosphorus, Mn, Ni, B, Mo, Cr, Cu, Zn, and Ba, in HW exceeded 50%. Ni, Cr, and Ba are notably not recommended components of nutrient solutions in South Korea. Among the micropollutants, the concentration of Cu, which is a recommended component, was the highest, at 10.317 mg/L. The PER assessment identified Cu and Zn as "high-hazard" pollutants, with Cu, Zn, Ni, Mn, and B prioritized for management. To ensure the sustainability of hydroponic cultivation, these five pollutants must be managed. Nature-based techniques, such as the implementation of constructed wetlands and phyto-filtration, are recommended for effective treatment. [ABSTRACT FROM AUTHOR]

This research was conducted in Suntenjaya Village, Lembang, and West Bandung Regency, focusing on lemon agro-industrial development. Research was conducted using the Analytical Hierarchy Process (AHP) approach, area mapping, and water management to determine a sustainable factory location. The main objective is the selection of factory sites by integrating lemon production, considering sustainable agriculture aspects, product aspects, and water conservation programs. The results of this study provide a strong foundation for sustainable agro-industrial development that will support sustainable agriculture, local economy, and environmental protection. The research also combined qualitative and quantitative elements with a mixed approach that included Focus Group Discussion (FGD) and AHP, and the results showed that integrated drainage management was the top priority, followed by sanitation, clean water, reforestation, and sustainable agriculture. Mapping of areas based on geographical characteristics, such as rainfall, slope, and soil type, provided a map of water infiltration rates, which became a key guide in planning water conservation programs. The ultimate location for the lemon agroindustry is half of Desa Suntenjaya, mostly from the center to the northern area, which needs to consider proximity to markets in Bandung Regency and City, easy access to sources of raw materials for lemons, water availability, adequate transportation infrastructure, access to energy sources, suitable climate for lemon growth, and the availability of adequate labor in the region. [ABSTRACT FROM AUTHOR]

Sustaining crop production and food security are threatened by a burgeoning world population and adverse environmental conditions. Traditional breeding methods for vegetable crops are time-consuming, laborious, and untargeted, often taking several years to develop new and improved varieties. The challenges faced by a long breeding cycle need to be overcome. The speed breeding (SB) approach is broadly employed in crop breeding, which greatly shortens breeding cycles and facilities plant growth to obtain new, better-adapted crop varieties as quickly as possible. Potential opportunities are offered by SB in plant factories, where optimal photoperiod, light quality, light intensity, temperature, CO2 concentration, and nutrients are precisely manipulated to enhance the growth of horticultural vegetable crops, holding promise to surmount the long-standing problem of lengthy crop breeding cycles. Additionally, integrated with other breeding technologies, such as genome editing, genomic selection, and highthroughput genotyping, SB in plant factories has emerged as a smart and promising platform to hasten generation turnover and enhance the efficiency of breeding in vegetable crops. This review considers the pivotal opportunities and challenges of SB in plant factories, aiming to accelerate plant generation turnover and improve vegetable crops with precision and efficiency. [ABSTRACT FROM AUTHOR]

Container farms (CFs), a controlled environment agricultural technology designed to solve food insecurity, are receiving increasing attention from researchers. However, the complex geometric structures and artificial lighting used in CFs present challenges in effectively controlling the thermal environment. This study aims to identify the primary factors that impact the thermal environment of CFs while conducting factor ranking and significance analysis, providing a theoretical basis for future thermal environment optimization. The research method of theoretical analysis, CFD simulation, and an orthogonal experimental design were adopted to achieve the above objectives. Theoretical analysis revealed that factors influencing the thermal environment are the HVAC system's supply air temperature, humidity, flow rate, and the light source used. Four evaluation indices, including the mean value and range between layers of temperature and moisture content, were used. The results revealed that supply air temperature and light source are significant for mean temperature, while supply air temperature and humidity are significant for mean moisture content. In the case of range between layers, supply air flow rate and light source display a significant correlation. These findings suggest that future optimization should prioritize the regulation of the HVAC system's supply air and light source. [ABSTRACT FROM AUTHOR]

The effect of the ratio of red and blue light on fruit biomass radiation-use efficiency (FBRUE) in dwarf tomatoes has not been well studied. Additionally, whether white light offers a greater advantage in improving radiation-use efficiency (RUE) and FBRUE over red and blue light under LED light remains unknown. In this study, two dwarf tomato cultivars ('Micro-Tom' and 'Rejina') were cultivated in three red-blue light treatments (monochromatic red light, red/blue light ratio = 9, and red/blue light ratio = 3) and a white light treatment at the same photosynthetic photon flux density of 300 mmol m-2 s-1. The results evidently demonstrated that the red and blue light had an effect on FBRUE by affecting RUE rather than the fraction of dry mass partitioned into fruits (Ffruits). The monochromatic red light increased specific leaf area, reflectance, and transmittance of leaves but decreased the absorptance and photosynthetic rate, ultimately resulting in the lowest RUE, which induced the lowest FBRUE among all treatments. A higher proportion of blue light (up to 25%) led to a higher photosynthetic rate, resulting in a higher RUE and FBRUE in the three red-blue light treatments. Compared with red and blue light, white light increased RUE by 0.09-0.38 g mol-1 and FBRUE by 0.14-0.25 g mol-1. Moreover, white light improved the Ffruits in 'Rejina' and Brix of fruits in 'Micro-Tom' and both effects were cultivar-specific. In conclusion, white light may have greater potential than mixed red and blue light for enhancing the dwarf tomato FBRUE during their reproductive growth stage. [ABSTRACT FROM AUTHOR]

This study examined how the nutrient flow environment affects lettuce root morphology in hydroponics using multi‐omics analysis. The results indicate that increasing the nutrient flow rate initially increased indicators such as fresh root weight, root length, surface area, volume, and average diameter before declining, which mirrors the trend observed for shoot fresh weight. Furthermore, a high‐flow environment significantly increased root tissue density. Further analysis using Weighted Gene Co‐expression Network Analysis (WGCNA) and Weighted Protein Co‐expression Network Analysis (WPCNA) identified modules that were highly correlated with phenotypes and hormones. The analysis revealed a significant enrichment of hormone signal transduction pathways. Differences in the expression of genes and proteins related to hormone synthesis and transduction pathways were observed among the different flow conditions. These findings suggest that nutrient flow may regulate hormone levels and signal transmission by modulating the genes and proteins associated with hormone biosynthesis and signaling pathways, thereby influencing root morphology. These findings should support the development of effective methods for regulating the flow of nutrients in hydroponic contexts. [ABSTRACT FROM AUTHOR]

Computational fluid dynamics (CFD) simulations have been extensively used in designing air distribution systems for controlled environment agriculture (CEA). In recent years, more application studies using CFD simulations can be found for vertical farms due to the increasing interest in indoor vertical farming systems. However, it is well-known that CFD simulations are sensitive to many computational parameters and settings. The requirement of a crop response model in the CFD simulation for a vertical farm makes it even more complicated. Despite increased interest, guidelines for CFD simulations in vertical farms are scarce based on a literature study. Therefore, a systematic sensitivity analysis is conducted for a small generic multi-layer vertical farm with sole source lighting, which was the object of study in the literature before. The impact of a wide range of computational and physical parameters is investigated, including grid resolution, turbulence model, turbulence intensity, discretisation scheme, drag coefficient of the crops and computational time. The analysis shows that in this case (inlet Re = 46,923, Ar = 0.078, cultivated with lettuce), the RNG k-ε turbulence model outperforms other commonly used two-equation turbulence models. Compared to the experimental results from the literature, the simulation results from the first-order upwind scheme show large discrepancies, especially on the coarse grid. Although the influence of drag coefficient on the airflow inside the crop canopy is pronounced, little difference is observed in the air distributions in the vertical farm away from the crops. • Literature review on computational settings in CFD simulations of indoor farming. • Validation of RANS CFD simulations including a crop response model. • RNG k-ε turbulence model outperforms the other two-equation turbulence models. • First-order upwind discretisation scheme shows large discrepancies. • Influence of the momentum sink of lettuce canopy on the air distributions is limited. [ABSTRACT FROM AUTHOR]

Unable to move on their own, plants have acquired the ability to produce a wide variety of low molecular weight compounds to survive against various stresses. It is estimated that there are as many as one million different kinds. Plants also have the ability to accumulate high levels of proteins. Although plant-based bioproduction has traditionally relied on classical tissue culture methods, the attraction of bioproduction by plants is increasing with the development of omics and bioinformatics and other various technologies, as well as synthetic biology. This review describes the current status and prospects of these plant-based bioproduction from five advanced research topics, (i) de novo production of plant-derived high value terpenoids in engineered yeast, (ii) biotransformation of plant-based materials, (iii) genome editing technology for plant-based bioproduction, (iv) environmental effect of metabolite production in plant factory, and (v) molecular pharming. [ABSTRACT FROM AUTHOR]

In this paper, the indoor environment of a small-scale high-density controlled environment agriculture (CEA-HD) space was simulated using computational fluid dynamics. Spatial modelling of the indoor environment considering the influential phenomena (e.g. transpiration and photosynthesis) over the indoor temperature, relative humidity, carbon dioxide (CO2) concentration, and airflow velocity is still challenging. These indoor environment conditions were computed for a 3D model of a CEA-HD experimental space while simultaneously modelling crop airflow impingement, transpiration and photosynthesis. The crops being grown were represented in the model as porous media zones and their exchanges with the indoor air were modelled using user defined functions. The air distribution parameters and configuration were optimized using a simplified 2D model to overcome the steep computational time, and associated cost, of 3D simulation. The objective function of the optimization problem relied on a correlation analysis of the simulation output. The optimization of the 2D model yielded an airfoil configuration that reduced the mean airflow speed and relative humidity variations between the cultivation tiers while achieving higher mean velocities (≈1.9 m·s−1) at a lower inlet speed (8 m·s−1). The proposed modelling and optimization approach is a small step forward towards model-based design and operation of CEA-HD production spaces.

Indoor vertical farms can optimize light, temperature, humidity, and nutrient use, thus potentially maximizing crop growth and yield. However, the reported potential for enhanced crop growth and yield within these systems needs to be tempered against the understanding of the effects of this “forced growth”/optimal growth environment on “actual” plant performance to fully reap the benefits of these innovative vertical farming systems. We investigated the effect of calcium (Ca) on the production of strawberries in an indoor vertical farm system with varying photosynthetic photon flux density (PPFD). Fruit yield of plants fed with high Ca (9 meq·L−1) increased by 42.3% when the PPFD was 422 µmol·m−2·s−1; however, a subsequent increase to 572 µmol·m−2·s−1 resulted in a decline in fruit production. Plants treated with low Ca (5 meq·L−1) had a reduced yield and demonstrated no response to the PPFD. The observed increase in yield was associated with increased fruit production and total soluble solids. Plants exhibited 21.5% and 57.8% increases in the total dry weight when exposed to 422 and 572 µmol·m−2·s−1, respectively; however, Ca did not have any impact on this response. Independent of the Ca concentration, the photosynthesis rate increased by 16.1% and 22.2% when the PPFD increased to 422 and 572 µmol·m−2·s−1, respectively; however, the highest photosynthesis rate was recorded with 422 µmol·m−2·s−1 when the Ca level was 9 meq·L−1. High Ca-fed plants exhibited a reduction in Ca (−17.1%) content in their fruits when exposed to 572 µmol·m−2·s−1, which was likely caused by a dilution effect attributable to increased fruit biomass. In contrast, shoot Ca increased when plants were given high Ca when the PPFDs were 422 and 572 µmol·m−2·s−1. The Ca concentration in shoots correlated with the increasing yield, and a higher Ca concentration was associated with the increasing transpiration rate and stomatic conductance. Shoot phosphorus declined when plants were exposed to increased PPFD, and phosphorus was lower when plants were provided with 9 meq·L−1 of Ca; however, plants watered with low Ca solutions had more potassium. The shoot nitrogen content and micronutrient contents were unchanged regardless of the variations in PPFD or Ca. In summary, the favorable conditions for the cultivation of strawberry under controlled environments resulted in greater growth and fruit yield as long as Ca was provided at higher concentrations in the irrigation solutions (from 5 to 9 meq·L−1). We suggest that the higher demand of Ca that is necessary to satisfy the enhanced plant development observed in indoor farming systems may be connected to the role of Ca in the formation of new tissues, cell walls, and cell membranes.

During this study, an indoor experiment was conducted to determine the effect of mixed seeding rates of legumes used as green manure on the substrate fertilizer, growth characteristics, and bioactive compounds of baby leaf vegetables. The mixed seeding treatment was designed for milkvetch (Astragalus sinicus L.), tatsoi (Barassica rapa L.), kale (Brassica oleracea var. sabellica L.), and spinach (Spinacia oleracea L.) using five rates for each. Accordingly, a total of 15 treatments (3 baby leaf species × 5 mixed seeding rates) were constructed using a randomized complete block design with three replications for each treatment. During the baby leaf vegetable harvest, we evaluated the macronutrient levels (nitrogen, phosphorus, and potassium) in the substrate as well as the growth parameters and carotenoid contents. The substrate in the treatment mixed with milkvetch showed significantly higher levels of nitrogen, phosphorus, and potassium compared with those of tatsoi and kale sown alone (P ≤ 0.05). However, there were no significant differences in macronutrients observed in substrate-sown spinach with or without the milkvetch mixture. The growth and carotenoid levels of each baby leafy vegetable sown alone were significantly higher than those of each baby leafy vegetable sown with the mixed seeding treatment (P ≤ 0.05). Sowing the milkvetch-vegetable mixtures did not result in a significant increase in the growth and carotenoid levels of the three baby vegetables. The results showed that planting milkvetch with tatsoi and kale had a significant impact on substrate fertilization. However, regarding short-term vertical indoor farming, the growth and carotenoid responses of the three greens may be different. Nonetheless, we still believe that the combined interactions of legumes can provide long-term benefits by enhancing the biological functionality of the growing medium for balanced indoor agriculture production. [ABSTRACT FROM AUTHOR]

Pea shoots is a popular vegetable in certain regions of the world due to their unique taste and abundance of health-promoting phytochemicals. The perishable nature and susceptibility to root rot of pea shoots necessitate a new soilless production system located close to the market. This study compared the growth of pea shoots using various cultivation methods in an LED plant factory. The results showed that early topping (4 days after transplanting, ET) promoted early harvest compared to later topping (20 days after transplanting, LT) and increased the number of harvested shoots by extending the harvest time to 2.8 times, ultimately resulting in a substantial yield improvement. Moreover, the yield of ET with a lower planting density (72 plants m−2, ET-LD) was 8.7% higher than ET with a higher planting density (126 plants m−2, ET-HD). Particularly, the average shoot fresh weight (AFW) under ET-LD exceeded that of ET-HD by 48.9%. It is advisable to consider adopting ET-LD for the cultivation of pea shoots in LED plant factories. Based on ET-LD, the yield, nutritional quality, and light use efficiency of pea shoots were further explored at different stages under three levels of light intensity (50, 100, and 150 μmol m−2·s−1). Contrasted against a light intensity of 50 μmol m−2·s−1, AFW, number of harvested shoots, and total fresh yield under a light intensity of 150 μmol m−2·s−1, increased by 60.2%, 62.8%, and 165.1%, respectively. Meanwhile, AFW, photosynthetic capacity, soluble sugar and vitamin C levels in leaves, as well as light use efficiency and photon yield, initially increased and then decreased with the extension of the planting period. Among these, soluble sugar, light use efficiency, and photon yield started to decrease after reaching the maximum value at 60–70 days after transplanting. In conclusion, a light intensity of 150 μmol m−2·s−1 with a photoperiod of 16 h d−1 using LEDs, combined with early topping within a planting period of 60–70 days, proves to be suitable for the hydroponic production of pea shoots in LED plant factories. [ABSTRACT FROM AUTHOR]

Plant factories offer a promising solution to some of the challenges facing traditional agriculture, allowing for year-round rapid production of plant-derived foods. However, the effects of conditions in plant factories on metabolic nutrients remain to be explored. In this study, we used three rice accessions (KongYu131, HuangHuaZhan, and Kam Sweet Rice) as objectives, which were planted in a plant factory with strict photoperiods that are long-day (12 h light/12 h dark) or short-day (8 h light/16 h dark). A total of 438 metabolites were detected in the harvested rice grains. The difference in photoperiod leads to a different accumulation of metabolites in rice grains. Most metabolites accumulated significantly higher levels under the short-day condition than the long-day condition. Differentially accumulated metabolites were enriched in the amino acids and vitamin B6 pathway. Asparagine, pyridoxamine, and pyridoxine are key metabolites that accumulate at higher levels in rice grains harvested from the short-day photoperiod. This study reveals the photoperiod-dependent metabolomic differences in rice cultivated in plant factories, especially the metabolic profiling of taste- and nutrition-related compounds. [ABSTRACT FROM AUTHOR]

The tomato variety 'Micro Tom' is used as an experimental material in a fully artificial light-type plant factory. An LED light with adjustable illumination modes was used as the light source and a pure white LED light was used as the control. Different illumination mode, such as pure red light, pure blue light, mixed red and blue light, and alternating red and blue light were used as supplementary light. The influence of different red and blue supplemental lighting modes on the growth, development, and fluorescence characteristics of greenhouse tomatoes was explored. The results showed that: (1) in all treatments, the growth indicators and fruit weight of the tomato plants increased to a certain extent. The dynamic change of chlorophyll fluorescence was significantly affected by supplementary light. Pure red light supplementation had the greatest effect on the increase in plant height, stem thickness, leaf area, and yield of the tomato plants. Alternating red and blue light supplementation at intervals of 1h or 6h significantly promoted the increase in chlorophyll content and the improvement of PSII photosynthetic performance. (2) During the vegetative growth stage of tomatoes, under pure red light supplementation, the relative growth rate and absolute growth rate of plant height increased by 106.8% and 60% respectively compared to the control. The relative growth rate and absolute growth rate of stem thickness increased by 50% and 80% respectively. 44 days after sowing, the leaf area of the tomato plants under pure red light supplementation increased by 92.1% compared to the control.(3) During the reproductive growth period of tomatoes, compared with the control, 83 days after sowing, the number of fruits set under pure red light supplementation increased by 73.6%. The horizontal and vertical diameters and volume of tomato fruit increased by 34.4%, 35.3%, and 129.6% respectively.(4) Compared with the control, 44 days after sowing, the chlorophyll content in tomato leaves under alternating red and blue light supplementation at intervals of 1h or 6h increased by 30.3% and 31.8% respectively. 83 days after sowing, the performance index (PIABS) of tomato plants after alternating red and blue light supplementation at intervals of 1h or 6h increased by 100% and 30% respectively compared to the control. The electron transfer efficiency (ETo/CS) of PSII after alternating red and blue light supplementation at intervals of 1h or 6h increased by 16% and 23% respectively compared to the control. In summary, pure red light supplementation can effectively promote the growth and development of facility tomatoes. Alternating red and blue light supplementation at intervals of 1h or 6h significantly affects the fluorescence characteristics of tomatoes. In the future, the most suitable supplementary lighting mode can be chosen based on different production objectives. [ABSTRACT FROM AUTHOR]

In recent years, a plant factory has gradually become a new model of facility agriculture, and the optimization problem of low-carbon design of production system in a plant factory has become more prominent. In the design of the production system, needs of high efficiency, high yield, and low carbon emission must be considered. In this study, the leafy vegetable factory is taken as the research object, and the carbon footprint calculation model of products is established based on the life cycle assessment method. Taking production capacity and carbon footprint as design indicators, the logical correlation and mathematical relationship between them and production line design parameters are analyzed layer by layer to determine the key design parameters. The leafy vegetable production line is modeled by plant simulation software, and multifactor simulation experiments are set up to explore the influence of key design parameters on design indexes to guide the optimal decision of parameter design scheme. The new design scheme increases the productivity of the plant factory by 35.40%, reduces the carbon footprint of leafy vegetables by 15.54%, and solves the problem that leafy vegetables at the bottom of the planting frame in the original plant factory grow poorly because of insufficient light. [ABSTRACT FROM AUTHOR]

While it is commonly understood that air temperature can greatly affect the process of photosynthesis and the growth of higher plants, the impact of root zone temperature (RZT) on plant growth, metabolism, essential elements, as well as key metabolites like chlorophyll and carotenoids, remains an area that necessitates extensive research. Therefore, this study aimed to investigate the impact of raising the RZT on the growth, metabolites, elements, and proteins of red leaf lettuce. Lettuce was hydroponically grown in a plant factory with artificial light at four different air temperatures (17, 22, 27, and 30°C) and two treatments with different RZTs. The RZT was raised 3°C above the air temperature in one group, while it was not in the other group. Increasing the RZT 3°C above the air temperature improved plant growth and metabolites, including carotenoids, ascorbic acids, and chlorophyll, in all four air temperature treatments. Moreover, raising the RZT increased Mg, K, Fe, Cu, Se, Rb, amino acids, and total soluble proteins in the leaf tissue at all four air temperatures. These results showed that raising the RZT by 3°C improved plant productivity and the metabolites of the hydroponic lettuce by enhancing nutrient uptake and activating themetabolism in the roots at all four air temperatures. Overall, this research demonstrates that plant growth and metabolites can be improved simultaneously with an increased RZT relative to air temperature. This study serves as a foundation for future research on optimizing RZT in relation to air temperature. Further recommended studies include investigating the differential effects of multiple RZT variations relative to air temperature for increased optimization, examining the effects of RZT during nighttime versus daytime, and exploring the impact of stem heating. This research has the potential to make a valuable contribution to the ongoing growth and progress of the plant factory industry and fundamental advancements in root zone physiology. Overall, this research demonstrates that plant growth and metabolites can be improved simultaneously with an increased RZT relative to air temperature. This study serves as a foundation for future research on optimizing RZT in relation to air temperature. Further recommended studies include investigating the differential effects of multiple RZT variations relative to air temperature for increased optimization, examining the effects of RZT during nighttime versus daytime, and exploring the impact of stem heating. This research has the potential to make a valuable contribution to the ongoing growth and progress of the plant factory industry and fundamental advancements in root zone physiology. [ABSTRACT FROM AUTHOR]

Xiang FZ001 was used as a test variety in this experiment, which was conducted in a plant factory with a cycle of 16 hours of light and 8 hours of darkness to study the effects of varying light intensities on the growth and development of cotton (Gossypium hirsutum L.), three light intensity treatments with parameters of L1: 450 µmol⋅m-2⋅s-1, L2: 600 µmol⋅m-2⋅s-1, and L3: 750 µmol⋅m-2⋅s-1, were established to determine the dry weight of each cotton organ. The height of the cotton plant was measured using a straightedge, the chlorophyll content of cotton leaves was measured using a SPAD-502 chlorophyll meter. Additionally, six chlorophyll fluorescence parameters were measured, including initial fluorescence (F0) and maximum fluorescence (Fm), using a Flour Pen 110. The relative chlorophyll content and plant height of cotton were greatest under the L1 light intensity treatment, the root dry weight of cotton was greatest under the L2 light intensity treatment, and the total weight of cotton stems, leaves, and individual plants under the three light intensity treatments were L3>L2>L1 in descending order, and the F0 and Fm were L1>L2>L3 in descending order. The maximum photochemical quantum yield (Fv/Fm) was L2>L3>L1 in descending order. The photochemical bursting coefficient (qp) and effective quantum yield (φPSII) of cotton under the same light intensity treatment showed the same curves of change. During the pre-growth era, there was no significant difference in the qp, φPSII, and nonphotochemical burst (NPQ) of cotton under the three light intensity treatments. However, in the late period, there was a greater difference. For the late growth stage, cotton's qp and φPSII under the three light intensity treatments were high to low in the order of L3>L2>L1, and high to low in the order of L2>L3>L1. High light intensities increase the dry weight, stem dry weight, and leaf dry weight of cotton plants; low light intensities enhance the height of the cotton plant, but too high or too low a light intensity prevents the growth of cotton roots. Compared with cotton under L1 and L3 light intensity treatments, L2 light intensity was suitable for cotton growth, avoiding both inter-plant competition for light and the phenomenon of photoinhibition, with moderate chlorophyll content, resulting in the highest photochemical efficiency of cotton. This study can provide a guidance for cotton factory production and cotton breeding accelerator development and application. [ABSTRACT FROM AUTHOR]

To drive LEDs for plant cultivation using an alternating-current (AC) power supply, full-wave rectification (FWR) is a reasonable method to supply a unidirectional forward current to LEDs because of the simple configuration and low energy loss of the rectification circuit. We grew cos lettuce hydroponically using a white LED light source that emitted continuous light, 100 Hz square-wave (SW) pulsed light, or pulsed light generated with FWR of 50 Hz sine-wave AC with the same averaged photosynthetic photon flux density of 150 µmol m-2 s-1. The results showed that shoot fresh weight, shoot dry weight, leaf area, and number of leaves did not differ significantly among the treatments. Plants grown under FWR pulsed light showed similar net photosynthetic rates under continuous light and SW pulsed light. Shoot fresh weight per power consumption was estimated to be significantly greater with FWR pulsed light than with continuous light, and we concluded that the use of FWR pulsed light without elaborated transformation to a flat waveform direct current is a promising lighting method to reduce the lighting cost. [ABSTRACT FROM AUTHOR]

Real-time monitoring and management of lettuce plants, especially during the seedling growth stage, is important in order to protect them from various environmental stresses and to prevent yield loss. Various and similar symptoms may occur as a result of different unfavorable environmental stresses. Visual inspection alone may result in an incorrect and late diagnosis, obstructing subsequent corrective action for the damaged seedlings in an early stage. The purposes of this study were to detect and segment lettuce seedlings from the background of seedling-growing trays using an improved mask R-CNN and to estimate seedling size based on the output of the proposed technique. Lettuce seedling images were taken from a plant factory using an automatic image acquisition tool. The seedlings in the images were 1 to 3 weeks old. An annotation of 1,000 lettuce seedling image datasets was prepared using an online annotation tool. An improved mask R-CNN was implemented using ResNet-101 with CB-Net, which provided enhanced image feature extraction. Transfer learning was used to train the model network with a smaller dataset and reduce the processing time. Bounding boxes and annotations were set as inputs for the training model. Training and test datasets were prepared for the model evaluation. The sizes of the seedlings were determined by applying a binary mask to the output-masked seedling images. The total number of pixels was used to determine the seedling size. The training loss of the selected method was less than 0.20 %. The identification of lettuce seedlings from 150 randomly chosen test photos revealed that the best-fit image had a performance F1 score of 93 %, corresponding to 92 % precision and 95 % recall. A strong linear relationship (R2>0.99) between manual and model-estimated leaf area confirmed the proposed model accuracy throughout the lettuce growth stages. The improved mask R-CNN could detect lettuce seedlings in the tray image background and also extract the leaf area of identified lettuce seedlings.

In the context of plant factories relying on artificial light sources, energy consumption stands out as a significant cost factor. Implementing early seedling removal and replacement operations has the potential to enhance the yield per unit area and the per-energy consumption. Nevertheless, conventional transplanting machines are limited to handling older seedlings with well-established roots. This study addresses these constraints by introducing a transplanting workstation based on the UR5 industrial robot tailored to early plug tray seedlings in plant factories. A diagonal oblique insertion end effector was employed, ensuring stable grasping even in loose substrate conditions. Robotic vision technology was utilized for the recognition of nongerminating holes and inferior seedlings. The integrated robotic system seamlessly managed the entire process of removing and replanting the plug tray seedlings. The experimental findings revealed that the diagonal oblique-insertion end effector achieved a cleaning rate exceeding 65% for substrates with a moisture content exceeding 70%. Moreover, the threshold-segmentation-based method for identifying empty holes and inferior seedlings demonstrated a recognition accuracy surpassing 97.68%. The success rate for removal and replanting in transplanting process reached an impressive 95%. This transplanting robot system serves as a reference for the transplantation of early seedlings with loose substrate in plant factories, holding significant implications for improving yield in plant factory settings.

This paper proposes a novel method to predict the fresh weight of lettuce at the shipping stage in a plant factory using the early-stage growth images. It is well-established that the size and shape of plants correlate with their fresh weight. The proposed method captures chlorophyll fluorescence-based growth images daily and extracts geometric features such as projection area, edge length, and skeleton length. We design a regression model to predict the fresh weight using the dimensionality-reduced historical features. However, without considering growth statuses, the dimensionality reduction approach leads to decreased predictive performance for mature and slower-growing plants. In this paper, we generate a plant growth model that simulates the growth process by integrating multiple growth records based on the comparison of growth statuses. The proposed method then reduces the dimensionality by fitting historical features to the plant growth model to obtain future features. Experimental results demonstrate that the proposed method accurately predicts the fresh weight and achieves the coefficient of determination of 0.885, root mean square error of 8.790 g, and mean absolute error of 6.684 g when predicting the fresh weight ten days ahead using growth images from the past ten days.

In blueberry (Vaccinium corymbosum L.), a perennial shrub, flower bud initiation is mediated by a short-day (SD) photoperiod and buds bloom once the chilling requirement is satisfied. A plant factory with artificial lighting (PFAL) is a planting system that can provide a stable and highly efficient growing environment for blueberry production. However, the characteristics of bud differentiation of blueberry plants inside PFAL systems are poorly understood. To better understand flower bud initiation and the flowering mechanism of blueberry in PFAL systems, the anatomical structure of apical buds under SD conditions in a PFAL system was observed using the southern highbush cultivar 'Misty' and a transcriptomic analysis was performed to identify the candidate flowering genes. The results indicated that the apical bud of 'Misty' differentiated gradually along with SD time course and swelled obviously when chilling was introduced. A total of 39.28 Gb clean data were generated, and about 20.31–24.11 Mb high-quality clean reads were assembled, yielding a total of 17370 differentially expressed genes (DEGs), of which 9637 were up-regulated and 7733 were down-regulated. Based on the functional annotation, 26 DEGs were identified including 20 flowering-related and 6 low-temperature DEGs, out of which the expressive level of four flowering-related DEGs (VcFT2, VcFPA, VcFMADS1, and VcCOP1) and two low-temperature-induced DEGs (VcTIL-1 and VcLTI 65-like) were confirmed by qRT-PCR with a good consistency with the pattern of transcriptome. Functional analysis indicated that VcFT2 was highly conserved with nuclear and cytoplasmic subcellular localization and was expressed mainly in blueberry leaf tissue. In Arabidopsis, ectopic overexpression of VcFT2 results in an early flowering phenotype, indicating that VcFT2 is a vital regulator of the SD-mediated flowering pathway in blueberry. These results contribute to the investigation of photoperiod-mediated flowering mechanisms of blueberry in PFAL systems. [ABSTRACT FROM AUTHOR]

In the context of plant factories relying on artificial light sources, energy consumption stands out as a significant cost factor. Implementing early seedling removal and replacement operations has the potential to enhance the yield per unit area and the per-energy consumption. Nevertheless, conventional transplanting machines are limited to handling older seedlings with well-established roots. This study addresses these constraints by introducing a transplanting workstation based on the UR5 industrial robot tailored to early plug tray seedlings in plant factories. A diagonal oblique insertion end effector was employed, ensuring stable grasping even in loose substrate conditions. Robotic vision technology was utilized for the recognition of nongerminating holes and inferior seedlings. The integrated robotic system seamlessly managed the entire process of removing and replanting the plug tray seedlings. The experimental findings revealed that the diagonal oblique-insertion end effector achieved a cleaning rate exceeding 65% for substrates with a moisture content exceeding 70%. Moreover, the threshold-segmentation-based method for identifying empty holes and inferior seedlings demonstrated a recognition accuracy surpassing 97.68%. The success rate for removal and replanting in transplanting process reached an impressive 95%. This transplanting robot system serves as a reference for the transplantation of early seedlings with loose substrate in plant factories, holding significant implications for improving yield in plant factory settings. [ABSTRACT FROM AUTHOR]

Simultaneous Localization and Mapping (SLAM), as one of the core technologies in intelligent robotics, has gained substantial attention in recent years. Addressing the limitations of SLAM systems in dynamic environments, this research proposes a system specifically designed for plant factory transportation environments, named GY-SLAM. GY-SLAM incorporates a lightweight target detection network, GY, based on YOLOv5, which utilizes GhostNet as the backbone network. This integration is further enhanced with CoordConv coordinate convolution, CARAFE up-sampling operators, and the SE attention mechanism, leading to simultaneous improvements in detection accuracy and model complexity reduction. While mAP@0.5 increased by 0.514% to 95.364, the model simultaneously reduced the number of parameters by 43.976%, computational cost by 46.488%, and model size by 41.752%. Additionally, the system constructs pure static octree maps and grid maps. Tests conducted on the TUM dataset and a proprietary dataset demonstrate that GY-SLAM significantly outperforms ORB-SLAM3 in dynamic scenarios in terms of system localization accuracy and robustness. It shows a remarkable 92.59% improvement in RMSE for Absolute Trajectory Error (ATE), along with a 93.11% improvement in RMSE for the translational drift of Relative Pose Error (RPE) and a 92.89% improvement in RMSE for the rotational drift of RPE. Compared to YOLOv5s, the GY model brings a 41.5944% improvement in detection speed and a 17.7975% increase in SLAM operation speed to the system, indicating strong competitiveness and real-time capabilities. These results validate the effectiveness of GY-SLAM in dynamic environments and provide substantial support for the automation of logistics tasks by robots in specific contexts. [ABSTRACT FROM AUTHOR]

Industrialized seeding production is one of the most important methods used to raise seedlings in a standardized and efficient manner. However, its consumption of light energy limits its development. In this paper, we studied the effects of LED light intensities (30 (L1), 60 (L2), 90 (L3), 120 (L4), 150 (L5), 180 (L6), and 210 (L7) µmol·m−2·s−1) on the phenotypic parameters and health index of seedlings during different growth stages (cotyledon flattening (CF), one bud and one leaf (OBOL), and one bud and two leaves (OBTL)). Ten out of sixteen plants were selected to measure the parameters in every treatment. The control group was treated with 150 µmol·m−2·s−1 all the time. The results show that the height of the L1-treated plants was greatest during the cotyledon flattening stage. The L7 treatment produced the largest stem diameter, the greatest biomass, the largest leaf area, and the largest leaf circumference, the values of which were 2.61 mm, 3.3 g, 60.67 cm2, and 39.71 cm, respectively. During the one bud and one leaf stage, the L1 treatment produced the tallest plants. The L7 treatment resulted in the largest stem diameter, the greatest biomass, the largest leaf area, and the largest leaf circumference. During the one bud and two leaves stage, the plant height, stem diameter, leaf circumference, and biomass produced of the L6 treatment were the greatest, with values of 68.37 mm, 3.09 mm, 51.54 cm, and 4.47 g. L5 resulted in the largest leaf area (63.91 cm2). The seedling index of the three stages showed an inflection point at the L4 level. The experimental results showed that the light intensity required by the cucumber seedlings was 120 µmol·m−2·s−1, 150 µmol·m−2·s−1, and 120 µmol·m−2·s−1 during the three stages, from the cotyledon flattening stage to the one bud and two leaves stage. The results provide references regarding the light required during the cultivation of cucumber seedlings. [ABSTRACT FROM AUTHOR]

In the plant factories using stereoscopic cultivation systems, the cultivation plate transport equipment is an essential component of production. However, there are problems, such as high labor intensity, low levels of automation, and poor versatility of existing solutions, that can affect the efficiency of cultivation plate transport processes. To address these issues, this study designed a cultivation plate transport system that can automatically input and output cultivation plates, and can flexibly adjust its structure to accommodate different cultivation frame heights. We elucidated the working principles of the transport system and carried out structural design and parameter calculation for the lift cart, input actuator, and output actuator. In the input process, we used dynamic simulation technology to obtain an optimum propulsion speed of 0.3 m·s−1. In the output process, we used finite element numerical simulation technology to verify that the deformation of the cultivation plate and the maximum stress suffered by it could meet the operational requirements. Finally, operation and performance experiments showed that, under the condition of satisfying the allowable amount of positioning error in the horizontal and vertical directions, the horizontal operation speed was 0.2 m·s−1, the maximum positioning error was 2.87 mm, the vertical operation speed was 0.3 m·s−1, and the maximum positioning error was 1.34 mm. Accordingly, the success rate of the transport system was 92.5–96.0%, and the operational efficiency was 176–317 plates/h. These results proved that the transport system could meet the operational requirements and provide feasible solutions for the automation of plant factory transport equipment. [ABSTRACT FROM AUTHOR]

The accurate prediction of lettuce physiological indexes is of great significance for the digital and accurate management of lettuce growth in plant factory environment. In order to provide a reference for the prediction of physiological indexes of leaf vegetable crops in plant factories, in this study, hydroponic lettuce from plant factories was taken as the research object, and the data of longest leaf length, leaf number, and plant height of hydroponic lettuce treated with 5 different nutrient solution formulations were collected. Physiological index data of lettuce were predicted by Sparrow Search Algorithm-Back Propagation neural network(SSA-BP). And mean absolute error(MAE), mean square error(Mean Square Error, MSE), root mean square error(RMSE), and mean absolute percentage error(MAPE) were used as precision indexes to analyze and evaluate the test results. The results showed that the mean absolute errors of SSA-BP neural network were 9.21, 0.563, and 8.34 for predicting the longest leaf length, number of leaves, and plant height of lettuce. The mean square errors were 143.79, 0.599, and 110.69. The root mean square errors were 11.991, 0.774, and 10.521, respectively. The mean absolute percentage errors were 15.639%, 6.181%, and 13.318%. All the evaluation indexes were better than those obtained by the traditional BP neural network. The prediction error in the experimental results was less than 16%, but the improvement of the prediction error was not obvious. Therefore, the SSA-BP neural network model could effectively predict the physiological indexes of lettuce, and the model had good prediction accuracy and generalization. [ABSTRACT FROM AUTHOR]

It is already known that light quality and intensity have major influences on the growth, etiolation, germination, and morphology of many plant species, but there is limited information about the effect of wavelength and light intensity on nutrient absorption by plants. Therefore, this study was established to evaluate the plant growth, stomata formation, chlorophyll index, and absorption of macro- and micronutrients by common bean plants under six light treatments. The experimental design was completely randomized and consisted of six treatments: strong blue (blue LED at high light intensity); weak blue (blue LED at low light intensity); strong red (red LED at high light intensity); weak red (red LED at low light intensity; pink (combined red + blue LED), and white (combined red + white led). The stomatal density (stomata mm−2); the SPAD index; plant height (cm); root length (cm); plant dry weight (g); root dry weight (g); and the concentrations of N, S, K, Mg, Ca, B, Zn, Mn, and Fe on leaf analysis were influenced by all treatments. We found that plant photomorphogenesis is controlled not only by the wavelength, but also by the light intensity. Etiolation was observed in bean plants under blue light at low intensity, but when the same wavelength had more intensity, the etiolation did not happen, and the plant height was the same as plants under multichromatic lights (pink and white light). The smallest plants showed the largest roots, some of the highest chlorophyll contents, and some of the highest stomatal densities, and consequently, the highest dry weight, under white LED, showing that the multichromatic light at high intensity resulted in better conditions for the plants in carbon fixation. The effect of blue light on plant morphology is intensity-dependent. Plants under multichromatic light tend to have lower concentrations of N, K, Mg, and Cu in their leaves, but the final amount of these nutrients absorbed is higher because of the higher dry weight of these plants. Plants under blue light at high intensity tended to have lower concentrations of N, Cu, B, and Zn when compared to the same wavelength at low intensity, and their dry weight was not different from plants grown under pink light. New studies are needed to understand how and on what occasions intense blue light can replace red light in plant physiology. [ABSTRACT FROM AUTHOR]

Stress-resilient and highly nutritious legume crops can alleviate the burden of malnutrition and food security globally. Here, we focused on cowpea, a legume grain widely grown and consumed in regions at a high risk of micronutrient deficiencies, and we discussed the past and present research on carotenoid biosynthesis, highlighting different knowledge gaps and prospects for increasing this micronutrient in various edible parts of the crop. The literature survey revealed that, although carotenoids are important micronutrients for human health and nutrition, like in many other pulses, the potential of carotenoid biofortification in cowpea is still underexploited. We found that there is, to some extent, progress in the quantification of this micronutrient in cowpea; however, the diversity in content in the edible parts of the crop, namely, grains, pods, sprouts, and leaves, among the existing cowpea genetic resources was uncovered. Based on the description of the different factors that can influence carotenoid biosynthesis and accumulation in cowpea, we anticipated that an integrated use of omics in breeding coupled with mutagenesis and genetic engineering in a plant factory system would help to achieve a timely and efficient increase in carotenoid content in cowpea for use in the food systems in sub-Saharan Africa and South Asia. [ABSTRACT FROM AUTHOR]

Bio-based carbon capture and utilization emerges as a critical pathway to mitigate carbon dioxide (CO2) emissions from industrial activities. Within this context, plant factories become an innovative solution for biological carbon capture within industrial parks, fed with the substantial carbon emissions inherent in industrial exhaust gases to maximize their carbon sequestration capabilities. Among the various plant species suitable for such plant factories, Pennisetum giganteum becomes a candidate with the best potential, characterized by its high photosynthetic efficiency (rapid growth rate), perennial feature, and significant industrial value. This paper studies the feasibility of cultivating Pennisetum giganteum within an intelligent plant factory situated in an industrial park. An automated and intelligent plant factory was designed and established, in which multiple rounds of Pennisetum giganteum cultivations were performed, and life cycle assessment (LCA) was carried out to quantitatively evaluate its carbon capture capacity. The results show that the primary carbon emission in the plant factory arises from the lighting phase, constituting 67% of carbon emissions, followed by other processes (15%) and the infrastructure (10%). The absorption of CO2 during Pennisetum giganteum growth in the plant factory effectively mitigates carbon emissions from industrial exhaust gases. The production of 1 kg of dry Pennisetum giganteum leads to a net reduction in emissions by 0.35 kg CO2 equivalent. A plant factory with dimensions of 3 m × 6 m × 2.8 m can annually reduce carbon emissions by 174 kg, with the annual carbon sequestration per unit area increased by 56% compared to open-field cultivation. Furthermore, large-scale plant factories exhibit the potential to offset the carbon emissions of entire industrial parks. These findings confirm the viability of bio-based carbon capture using intelligent plant factories, highlighting its potential for carbon capture within industrial parks. [ABSTRACT FROM AUTHOR]

Plant factories with artificial light are less affected than open-air areas to environmental factors in crop cultivation and are attracting attention as one of the solutions to the world's food problems. However, the cost of cultivation in plant factories is higher than open-air cultivation, and currently, profitable factory-grown crop varieties are limited to those that are small or have a short growing period. Tomatoes are one of the main crops consumed around the world, but due to their large plant height and width, they are not yet suitable for mass production in plant factories. In this study, the DWARF (D) and SELF-PRUNING (SP) genes of the GABA hyperaccumulating tomato variety #87-17 were genome-edited by the CRISPR-Cas9 method to produce dwarf tomato plants. The desired traits were obtained in the T1 genome-edited generation, and the fruit traits were almost the same as those of the original variety. On the other hand, the F2 cross between #87-17 and Micro-Tom containing the d and sp mutations was dwarfed, but the fruit phenotype was a mixture of the traits of the two varieties. This indicates that genome editing of these two genes using CRISPR-Cas9 can efficiently impart traits suitable for plant factory cultivation while retaining the useful traits of the original cultivar. [ABSTRACT FROM AUTHOR]

During this study, an indoor experiment was conducted to determine the effect of mixed seeding rates of legumes used as green manure on the substrate fertilizer, growth characteristics, and bioactive compounds of baby leaf vegetables. The mixed seeding treatment was designed for milkvetch (Astragalus sinicus L.), tatsoi (Barassica rapa L.), kale (Brassica oleracea var. sabellica L.), and spinach (Spinacia oleracea L.) using five rates for each. Accordingly, a total of 15 treatments (3 baby leaf species × 5 mixed seeding rates) were constructed using a randomized complete block design with three replications for each treatment. During the baby leaf vegetable harvest, we evaluated the macronutrient levels (nitrogen, phosphorus, and potassium) in the substrate as well as the growth parameters and carotenoid contents. The substrate in the treatment mixed with milkvetch showed significantly higher levels of nitrogen, phosphorus, and potassium compared with those of tatsoi and kale sown alone (P ≤ 0.05). However, there were no significant differences in macronutrients observed in substrate-sown spinach with or without the milkvetch mixture. The growth and carotenoid levels of each baby leafy vegetable sown alone were significantly higher than those of each baby leafy vegetable sown with the mixed seeding treatment (P ≤ 0.05). Sowing the milkvetch–vegetable mixtures did not result in a significant increase in the growth and carotenoid levels of the three baby vegetables. The results showed that planting milkvetch with tatsoi and kale had a significant impact on substrate fertilization. However, regarding short-term vertical indoor farming, the growth and carotenoid responses of the three greens may be different. Nonetheless, we still believe that the combined interactions of legumes can provide long-term benefits by enhancing the biological functionality of the growing medium for balanced indoor agriculture production.

Abstract Ozonated water (OW) is now being recognized as an innovative and eco-friendly solution for managing plant growth while also promoting the production of bioactive compounds and essential plant metabolites. This study aimed to identify the most effective duration of OW treatment to promote plant growth and accumulation of antioxidant activity and bioactive compounds in Agastache rugosa in a plant factory. Whole plants were subjected to OW soaking treatments for varying durations (0, 1, 10, 20, 40, and 80 s) at a concentration of 1 µmol·mol−1, once per week, at 0, 1, 2, 3, and 4 weeks after transplantation. Five weeks after transplantation, plant samples were collected for the analysis of their plant growth parameters, photosynthetic pigments and parameters, total flavonoid, antioxidant activity, and bioactive compounds. Stem length was decreased in all OW treatments, while the number of flower branches, the flower fresh and dry weights were significantly increased under 20, 40, and 80 s OW treatments than in the control group. The net photosynthetic rate decreased significantly in 20, 40, and 80 s OW treatments compared with the control. Chlorophyll a concentration was the highest in the 20-s OW treatment, and chlorophyll b concentration was the highest in the 10-s OW treatment. Total flavonoid levels in plants increased significantly under 20-, 40-, and 80-s OW treatments, and their antioxidant activity (superoxide dismutase, catalase, and peroxidase) were significantly higher under 40- and 80-s OW treatments than in the control. Rosmarinic acid content increased significantly under the 10- and 40-s OW treatments, whereas the tilianin and acacetin contents increased significantly under the 20-, 40-, and 80-s OW treatments compared to those in the control. Our results suggest that soaking whole plants in OW for 20–80 s enhances the flower growth and bioactive compounds in A. rugosa for medicinal use. Graphical Abstract

The effects of different concentration nutrient solution on the growth characteristics, yield and quality of lettuce (Lactuca sativa L. Lvju) were studied for providing appropriate nutrient concentrations for the planting of lettuce under plant factory conditions. In this experiment, different concentration nutrient solution of EC 1.0,1.5,2.0,2.5,3.0 dS/m (CK,T1,T2,T3, T4) were designed and the physiological indicators, yield, and quality of lettuce were measured at 14,21, and 28 d after planting. The results show that when planting 14,21, and 28 d, different concentration nutrient solution had a significant impact on the shoot fresh weight, shoot dry weight, root fresh weight, number of leaves, leaf thickness, plant stretching, stem, and chlorophyll content. The soluble sugar content had a little difference between 21 and 28 days of transplanting. Based on the above measurement indicators, when planting 28 d, the concentration of nutrient solution is better in the growth status of lettuce at T2 and T3, the optimal yield and quality, and it is a relatively suitable nutritional solution irrigation concentration. [ABSTRACT FROM AUTHOR]

【Objective】Light is the most important factor affecting plant growth, development, metabolism and external phenotype. In the process of plant growth, artificial light sources are often used instead of natural light to fill the seeds and seedlings to improve the quality, yield and efficiency of fruits and vegetables. Artificial light plant is one of the important ways for standardized and efficient seedling cultivation, but its high energy consumption, accounting for 60% to 80% of the total energy consumption of plant factories, seriously hinder the promotion and application of factory seedling technology. Therefore, reducing the energy consumption of light source and improving the utilization rate of light is one of the core goals for plant seedling.【Method】Aiming at the problems of fixed height, high energy consumption and difficult to match the light demand of seed and seedling growth, this study developed a precise light cultivation platform for seedlings based on Programmable Logic Controller (PLC) technology by combining theoretical analysis, model construction and experiment. Taking cucumber seedlings as the object, the performance of the light intensity control system of the precision light cultivation platform for seedlings was verified, and its effect on the growth of cucumber seedlings was explored.【Result】The experimental results showed that the light intensity and light distribution uniformity were improved after the optimization of the lamp bead structure. The developed platform can fill the light of cucumber seedlings by manual, automatic, Human Machine Interface (HMI) and host computer. Through the platform optical radiation energy consumption model and the layer level adjustment control strategy, the LED operating power is effectively reduced, saving about 40.65% of electric energy. The maximum and minimum relative error of the optical platform radiation model are 34.37% and 3.57%, respectively, and the average relative error is 11.45%. Cultivation experiments showed that under the same light intensity treatment, there was no significant difference in seedling phenotype parameters and strong seedling index by comparing the precision light cultivation platform with the traditional high floor fixed platform.【Conclusion】The precision light cultivation platform of seedlings based on PLC technology realizes automatic lifting and intelligent dimming, and saves up to 40.65% power without affecting the growth of seedlings.

An appropriate design for air distribution systems is crucial for achieving optimal and uniform growth conditions while reducing energy costs in vertical farms. This study employs steady computational fluid dynamics (CFD) simulations to investigate the influence of several key design parameters of air distribution systems in a small generic vertical farm with a lateral air supply. The simulation results reveal that an air supply orifice of reduced dimensions, positioned proximally to the LED lamps, coupled with an exhaust mechanism integrated into the corridor ceiling, proves most effective in removing the excess heat generated by the LED lamps. Moreover, enhanced uniformity in air distribution is attained by positioning the air supply closer to the LED lamps, utilizing larger orifices, and eliminating the corridor space. In contrast, the vertical distance between the lateral air exhaust orifices and the cultivated regions is found to have a negligible effect.