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Panax notoginseng (Burkill) F. H. Chen, as a traditional Chinese medicinal herb with significant therapeutic effects, is highly sensitive to environmental factors during its growth process, particularly light and water conditions. Under traditional field conditions, natural limitations make it difficult to achieve optimal yield and quality. This study aimed in the past to determine the optimal light–water interaction model for the year-round cultivation of P. notoginseng in a controlled plant factory environment. The experiment used one-year-old, uniformly grown P. notoginsen seedlings. At the beginning of the experiment, the light source, without any shading treatment, provided a photosynthetically active radiation (PAR) intensity of 200 μmol·m−2·s−1, measured at a distance of 30 cm from the plant canopy. A total of 18 treatment combinations were established, specifically two different light quality treatments (A Treatment with a red-to-blue light ratio of 4:1 and B Treatment with a red-to-blue light ratio of 5:1) were each combined with three irrigation levels (field water capacities of 40%, 50%, and 60%) and three shading levels (one layer of 60% shading net, two layers of 60% shading net, and three layers of 60% shading net). Each light quality treatment was combined with all three irrigation levels and all three shading levels, resulting in 18 distinct treatment combinations. The effects of different light–water interactions on P. notoginseng growth were evaluated by measuring key agronomic traits, chlorophyll fluorescence parameters, and ginsenoside content. The results indicate that light–water interactions significantly affect the agronomic traits, chlorophyll fluorescence parameters, and ginsenoside content of P. notoginseng (light treatment had a more significant impact on the growth of P. notoginsen than water treatment). The best performance in terms of plant height (15.3 cm), stem diameter (3.45 mm), leaf length (8.6 cm), fresh weight (3.382 g), and total ginsenoside content (3.8%) was observed when the red-to-blue light ratio was 4:1 (A Treatment), the field water capacity was 50%, and the shading level was three layers. Based on this, the Pearson correlation analysis was used to identify eight highly correlated indicators, and the entropy-weighted TOPSIS model was applied to comprehensively evaluate the cultivation schemes. The evaluation results show that the optimal cultivation scheme for P. notoginseng is under the conditions of a red-to-blue light ratio of 4:1 (A Treatment), field water capacity of 50%, and three-layer shading. [ABSTRACT FROM AUTHOR]

The agricultural sector faces significant challenges, including resource depletion, climate change, and a growing global population projected to reach 9 billion by 2050, requiring a 70% increase in food production. Innovative techniques like soilless farming are gaining attention as potential solutions to ensure sustainable food production. Although other bibliometric reviews have examined the possibilities of soilless farming technologies, focusing separately on certain fields such as hydroponics, aquaponics, and aeroponics, the novelty of this analysis is to provide a comprehensive view of soilless farming in the current research landscape. Using VOSviewer software (1.6.20), the study conducts a thorough analysis of 256 articles, looking at key themes, emerging trends and influential works in the field. The results showed the relevance of soilless farming and its strong link to field such as digitalization, sustainable food production, and biofortification. A strong promising area is the connection between soilless farming and urban agriculture, investigated as a theoretical tool to implement these systems in sustainable cities. The major gap emerged in the research is the lack of studies on the economic feasibility. According to the study's findings, policymakers ought to concentrate on allocating specific funds to encourage the adoption of soilless farming, especially in urban areas. [ABSTRACT FROM AUTHOR]

This study examines the impact of daily light integral (DLI) from artificial lighting on tomato seedlings cultivated in plant factories. By adjusting the light intensity and photoperiod of LED, the research explored the effects of varying DLIs on the morphology, growth, physiological characteristics, photosynthetic pigment content, and chlorophyll fluorescence of tomato seedlings. The optimal DLI enhanced seedling growth, biomass, root vitality, antioxidant enzyme activity, and photosynthetic pigment synthesis. Excessively high DLI or light intensity inhibited photosynthesis, potentially leading to photoinhibition. This study identified the optimal DLI of 13.2 mol·m−2·d−1 through varying DLI gradients in Exp 1 and Exp 2. Based on these findings, Exp 3 established the optimal growth conditions by setting different light intensities and photoperiods under the most suitable DLI, which were a light intensity of 200 μmol·m−2·s−1 and a photoperiod of 18 h. These results provide significant guidance for optimizing the light environment in the cultivation of tomato seedlings in plant factories, helping to improve the light energy utilization efficiency. [ABSTRACT FROM AUTHOR]

Medicinal plants are valued for their contributions to human health. However, the growing demand for medicinal plants and the concerns regarding their quality and sustainability have prompted the reassessment of conventional production practices. Controlled-environment cropping systems, such as vertical farms, offer a transformative approach to production of medicinal plants. By enabling precise control over environmental factors, such as light, carbon dioxide, temperature, humidity, nutrients, and airflow, controlled environments can improve the consistency, concentration, and yield of bioactive phytochemicals in medicinal plants. This review explores the potential of controlled-environment systems for enhancing production of medicinal plants. First, we describe how controlled environments can overcome the limitations of conventional production in improving the quality of medicinal plants. Next, we propose strategies based on plant physiology to manipulate environmental conditions for enhancing the levels of bioactive compounds in plants. These strategies include improving photosynthetic carbon assimilation, light spectrum signalling, purposeful stress elicitation, and chronoculture. We describe the underlying mechanisms and practical applications of these strategies. Finally, we highlight the major knowledge gaps and challenges that limit the application of controlled environments, and discuss future research directions. [ABSTRACT FROM AUTHOR]

Strawberries are valued globally for their nutritional, aesthetic, and economic benefits. Optimizing blue-to-red LED ratios and nitrogen levels is essential for sustainable indoor strawberry cultivation. This factorial study investigated the effects of blue and red LED combination ratios (L1; 1:3, L2; 1:4, and L3; 1:6) and nitrogen levels (N1; 100 and N2; 200 mg/L) on the physiology and performance of strawberries in a plant factory. The results revealed that the interaction of L3 coupled with N2 maximized the vegetative growth of strawberry plants, whereas L2 and N2 produced the greatest biomass, while L2 interacted with N1 to expedite flowering. Photosynthesis and transpiration were enhanced by L3, particularly with 100 mg/L of nitrogen. The highest fruit yield and total soluble solids were obtained at the interaction of L3 and N1. Leaf nutrient analysis showed the highest nitrogen concentration at L1, while potassium increased with higher red LED ratios. The 100 mg/L nitrogen treatment resulted in higher leaf potassium concentrations than the 200 mg/L. These findings emphasize that LED spectra and nitrogen levels interact to optimize the physiology, vegetative and reproductive growth, maximizing fruit yield and quality in indoor strawberry cultivation. The study also concludes that the application of blue and red LED in the ratio of 1:6 with 100 mg/L nitrogen can improve indoor 'Praratchatan 80' strawberry performance. [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.

Harvest time is one of the key factors for obtaining high-quality cherry tomatoes. This parameter depends on environmental conditions and tomato variety. In plant factories with artificial lighting (PFALs), it is possible to control environmental conditions to enhance tomato production and quality. Since the ripening status of tomato fruit is correlated with cumulative temperature (CT), and the temperature inside PFALs can be easily controlled, CT could be used as an alternative method to predict tomato harvest time. In this study, three experiments were conducted to determine the optimal CT for harvesting high-quality cherry tomatoes in a PFAL. The experiments aimed to (1) evaluate the yield and quality of cherry tomatoes as affected by different harvest times based on CT (ranging from 900 to 1400 °C), (2) comparatively evaluate the yield and quality of cherry tomatoes that were still on the plant and off the plant (in storage) based on the same CT levels (i.e., 1100, 1200, and 1300 °C), and (3) investigate the fruit-cracking percentage during the ripening stage based on CT levels. The results showed that the fruit harvested at lower CTs exhibited higher hardness values, while those harvested at higher CTs had a higher sugar content. The on-the-plant treatment resulted in a higher yield and sugar content compared with the off-the-plant treatment, indicating that harvesting tomatoes early would come at the expense of a certain yield and sweetness. Moreover, the fruit-cracking percentage tended to increase with increasing CT, possibly due to the fast fruit growth rate and increased internal turgor pressure. These results indicated that producers can use CT as an index to predict the harvest time, thereby optimizing profits in cherry tomato production. [ABSTRACT FROM AUTHOR]

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·L21) increased by 42.3% when the PPFD was 422 µmol·m-2·s21; 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 (217.1%) 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·m22·s21. 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·L21 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. [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. [ABSTRACT FROM AUTHOR]

A stagnant airflow area can often occur in the increasing cultivation layers in a plant factory with artificial light, leading to the low growth of the plant, and even physiologic diseases, like tipburn. Furthermore, stagnant airflow can also lead to uneven distribution of environmental factors in the plant canopy, resulting in uneven growth of plants. The optimal air velocity is in the range of 0.3-1.0 m/s in plant canopy. A ventilation system can effectively solve these challenges. Previous studies have focused on the airflow to the plant cultivation spaces. However, these ventilation systems can only provide a single direction of airflow with low penetration, which is heavily obstructed by leaves, resulting in stagnant airflow zones within the canopy. Besides, the devices can also increase the equipment complexity to decrease operational efficiency. In this study, an assembled system of dual channel aeration cultivation was designed to increase the airflow within the plant canopy using simple equipment with operation convenience. A cultivation experiment was conducted in a plant factory. There was one control group (common aeration ventilation of a plant factory generated an airflow velocity of 0.2 m/s within the plant canopy) and three experiment groups (the dual channel aeration ventilation mode generated the airflow velocity of 0.6 (T1 ), 0.9 (T2 ) and 1.2 (T3 ) m/s, respectively). A systematic investigation was made to explore the impact of different ventilation modes on plant growth, tipburn occurrence, heat exchange with the surrounding environment, and the canopy microenvironment. The results showed that the dual channel aeration ventilation outperformed the conventional one, in terms of the lettuce canopy environment, lettuce growth, and heat exchange capacity. Specifically, the best growth for lettuce plants was observed at a canopy airflow velocity of 0.9 m/s, with a shoot fresh weight of 56.7 g. The optimal canopy environment and heat exchange capacity for lettuce were achieved at a canopy airflow velocity of 1.2 m/s. There was a decrease of 8.8% and 2.8 ℃ in average canopy relative humidity and average air temperature, compared with the control group. The airflow regime was first transitioned from the laminar to a transitional flow and then changed to a turbulent flow at an airflow velocity of 0.9 m/s. The convective heat transfer coefficient was also significantly improved with the increasing airflow velocity. The sensible heat flux in the light and dark periods increased by 48.5% and 52.3%, respectively, while the latent heat flux rose by 52.9% and 37.9%, respectively, with the airflow velocity within the plant canopy increased from 0.2 m/s to 1.2 m/s. Besides, there was no tipburn occurred in the experiment groups, while the tipburn occurrence of the control group was 20.9%. It infers that the dual channel aeration ventilation can be expected to effectively alleviate tipburn. In conclusion, compared with the conventional ventilation mode, dual channel aeration ventilation can effectively enhance the plant canopy environment, plant yield, and quality, as well as heat exchange between plants and their surroundings. And the assembled structure can improve transportation and installation efficiency. Furthermore, the integrated structure of ventilation ducts and cultivation tanks also reduced equipment complexity. This mode can provide technical support to precise microenvironment control in plant factories. [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]

[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]

In recent years, food problems have arisen due to population changes. To solve this problem, Advanced technologies such as robots and artificial intelligence are increasingly being used to improve the efficiency of agriculture. In particular, plant factories are attracting attention because they have a high affinity for advanced technologies and can be produced regardless of the cultivation location and climate. However, production in plant factories exhibits of higher management costs and lower profitability than traditional cultivation methods. It is thought that this problem can be solved by predicting plant growth and notifying the farm manager. In this research, we will use data that can be measured at plant factories to create a machine learning model which predicts, both the size and weight of an agricultural product from a single piece of data. As a result, we were able to predict multiple items using a relatively lightweight model. The overall error was small, with an average error rate of about 15%. Although the average error rate for weight was about 30%, we were able to create a model that behaves close to the actual measured values. [ABSTRACT FROM AUTHOR]

As the global population exceeds 8 billion and is projected to reach 9.7 billion by 2050, the demand for sustainable food production has become increasingly pressing. This study investigates the integration of aquaponics into solar-assisted plant factories as an innovative solution to enhance agricultural productivity and minimize environmental impacts. The aquaponics establishes a closed-loop nutrient cycle, utilizing fish waste to nourish plants and optimize water recycling.Employing a two-tiered design, optimized through the Design of Experiments (DOE), the system enables effective resource management and operational efficiency. Operational data reveal the system's ability to maintain favorable temperature and humidity conditions, promoting uniform plant growth. The analysis identifies the mist irrigation method and LED lighting as critical factors that positively influence both root and leaf growth, establishing an optimal combination for sustainable cultivation.These findings underscore the potential of renewable energy-powered plant factories as a viable model for sustainable food production, contributing to local food self-sufficiency and regional economic revitalization. This research highlights the importance of advancing innovative agricultural practices to address the dual challenges of population growth and climate change, advocating for the development and implementation of sustainable technologies to secure future food production.

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]

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]

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]

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]

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]

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.

Strawberries are valued globally for their nutritional, aesthetic, and economic benefits. Optimizing blue-to-red LED ratios and nitrogen levels is essential for sustainable indoor strawberry cultivation. This factorial study investigated the effects of blue and red LED combination ratios (L1; 1:3, L2; 1:4, and L3; 1:6) and nitrogen levels (N1; 100 and N2; 200 mg/L) on the physiology and performance of strawberries in a plant factory. The results revealed that the interaction of L3 coupled with N2 maximized the vegetative growth of strawberry plants, whereas L2 and N2 produced the greatest biomass, while L2 interacted with N1 to expedite flowering. Photosynthesis and transpiration were enhanced by L3, particularly with 100 mg/L of nitrogen. The highest fruit yield and total soluble solids were obtained at the interaction of L3 and N1. Leaf nutrient analysis showed the highest nitrogen concentration at L1, while potassium increased with higher red LED ratios. The 100 mg/L nitrogen treatment resulted in higher leaf potassium concentrations than the 200 mg/L. These findings emphasize that LED spectra and nitrogen levels interact to optimize the physiology, vegetative and reproductive growth, maximizing fruit yield and quality in indoor strawberry cultivation. The study also concludes that the application of blue and red LED in the ratio of 1:6 with 100 mg/L nitrogen can improve indoor ‘Praratchatan 80’ strawberry performance.

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

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]

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]

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]

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]

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]