Search Results (40)

The increasing adoption of Plant Factories with Artificial Lighting (PFAL) has intensified the reliance on Internet of Things (IoT) technologies for real-time monitoring and control of environmental and operational variables. While IoT-based architectures enable precise resource management and productivity optimization, PFAL systems remain highly vulnerable to component failures, sensor malfunctions, communication faults, and energy disruptions, which may compromise crop integrity and system reliability. These risks are particularly critical in low-cost and small-scale PFAL implementations, where maintenance capacity and redundancy are often limited. Existing IoT-based PFAL monitoring systems typically address either hardware or software redundancy in isolation and rarely incorporate a dedicated maintenance-oriented fault detection layer validated under realistic multi-failure scenarios. This study addresses these challenges by proposing a low-cost redundant system architecture for PFAL applications that simultaneously integrates (1) hardware redundancy through multi-sensor configurations; (2) analytical redundancy based on residual generation and threshold-based fault isolation; and (3) a maintenance-oriented fault detection layer capable of identifying abnormal internal device conditions. Experimental validation was conducted using four hardware configurations—Arduino Nano with Ethernet, ESP32, STM32 with Wi-Fi, and STM32 with Ethernet—evaluated across five fault scenarios: dust accumulation, water exposure, high temperature, fire detection, and physical impact. The STM32 with Ethernet configuration consistently achieved the fastest fault detection response times across all tested scenarios. Future work will focus on the integration of machine learning-based predictive maintenance algorithms, multi-node PFAL network deployments, and long-term field validation. Full article

In plant factories with artificial lighting (PFALs), spectral regulation serves as the predominant factor governing plant growth and development. The implementation of red-enriched spectral regimens during cultivation promotes biomass accumulation, whereas blue-dominant spectra enhance the biosynthesis of phytochemicals and nutritional compounds in plants. Nevertheless, systematic investigations into the effects of staged spectral regimens on both plant development and secondary metabolite biosynthesis remain limited. This study evaluated four distinct stage-specific dynamic lighting regimens (T1–T4) under a constant total photosynthetic photon flux density (PPFD) of 200 μmol·m⁻²·s⁻¹. The treatments utilized three distinct red-to-white photon flux ratios (R:W = 3:1, 1:1, and 1:3) administered sequentially during critical developmental phases of Pak choi: the seedling stage, the early growth stage (15 days after transplanting, DAT), and the late growth stage (16–30 DAT). The effects of these treatments on biomass production, morphological development, photosynthetic pigments, nutritional metabolites, antioxidant levels and radical quenching capacity were evaluated. The results demonstrated that the T4 treatment significantly enhanced biomass production, increasing shoot fresh weight by 51.3% compared to the T1 treatment at the late growth stage. The application of a higher red-light proportion (HR, R:W = 3:1) during the seedling stage significantly increased leaf area by 70% compared to the low red-light treatment (LR, R:W = 1:3). Regarding nutritional quality, while carotenoid content showed no significant differences among treatments, higher blue-light proportions selectively stimulated the biosynthesis of chlorophyll, vitamin C, and soluble proteins. Specifically, the T3 treatment enhanced certain traits during the early growth stage, whereas the T2 treatment best maintained specific antioxidant capacities (FRAP and flavonoids) at the late growth stage prior to harvest. Notably, nitrate levels were not significantly affected by the spectral shifts. This study establishes that the temporal modulation of red-to-white spectral ratios enables the targeted optimization of either crop yield (T4) or specific harvest-stage nutritional attributes (T2) in Pak choi. Full article

As plant factories with artificial lighting (PFALs) expand beyond leafy greens to include flowering crops, understanding the role of light quantity and quality in regulating plant development becomes increasingly important. This study investigated how far-red (FR) radiation and daily light integral (DLI) influences flowering time, plant morphology, and FLOWERING LOCUS T (FT) gene expression in petunia. Four facultative commercial cultivars and one obligate long-day model cultivar, ‘Mitchell Diploid’, were grown under two DLI conditions with a gradient of FR radiation. Increasing FR consistently accelerated flowering across both DLI conditions without reducing flower bud number, branch number, or shoot fresh weight at harvest. Higher DLI generally produced more compact plants by reducing plant height and canopy area, whereas increasing FR promoted stem elongation, particularly in ‘Mitchell Diploid’. Cultivar responses varied substantially, indicating that genotype is an important factor when applying FR-based lighting strategies. To explore potential molecular mechanisms associated with FR-induced flowering acceleration, the expression levels of five petunia homologs, PhFT1 to PhFT5, were analyzed across developmental stages under low and supplemental FR conditions. PhFT2-5 expression was generally associated with flower initiation, with PhFT2 showing the strongest positive relationship with flowering and responsiveness to supplemental FR, whereas PhFT1 showed a decreasing trend over time and was not positively associated with flowering. Overall, this study demonstrates that FR radiation can be used to accelerate petunia flowering in PFAL production without compromising key quality traits and suggests that specific FT homologs, particularly PhFT2, may contribute to FR-mediated flowering regulation. Full article

Light availability is a key environmental factor regulating nitrogen assimilation, carbon metabolism, and nutritional quality in leafy vegetables grown in controlled environments. However, how practical lighting regimes used in plant factories with artificial lighting (PFALs) influence the coordination between nitrogen assimilation and central carbon metabolism across different lettuce cultivar types remains insufficiently understood. This study investigated how moderate differences in photosynthetic photon flux density (PPFD) influence nitrogen metabolism and metabolic coordination in hydroponically cultivated lettuce. Two cultivars representing contrasting morphological types, iceberg lettuce (‘Celebration’) and leaf lettuce (‘Sunny’), were grown under LED light intensities of 150 and 200 µmol·m⁻²·s⁻¹. Nitrate, nitrite, and ammonium concentrations were measured together with the activities of nitrate reductase (NRA) and nitrite reductase (NiRA), as well as ascorbic acid content. Metabolomic profiling was additionally performed to characterize broader metabolic responses. Higher light intensity enhanced nitrate reduction capacity in both cultivars, but the resulting patterns of nitrogen accumulation were strongly genotype-dependent. The leaf lettuce cultivar ‘Sunny’ exhibited increased NRA and reduced nitrate accumulation under higher light intensity, whereas the iceberg lettuce cultivar ‘Celebration’ accumulated more nitrate under the same conditions. Ammonium responses further suggested differences in downstream nitrogen assimilation processes. Elevated light intensity also increased ascorbic acid levels in both cultivars. Metabolomic analysis revealed contrasting cultivar-specific shifts in central carbon metabolism, particularly involving soluble sugars and tricarboxylic acid cycle intermediates, indicating differential coordination between carbon metabolism and nitrogen utilization. Overall, these findings demonstrate that moderate changes in light intensity within the practical PFAL cultivation range can significantly influence the integration of carbon and nitrogen metabolism in lettuce. Importantly, cultivar-specific physiological traits determine how these metabolic responses translate into nitrate accumulation and nutritional quality in controlled-environment production systems. Full article

This study evaluated the effects of different light-emitting diode (LED) spectral qualities on the early growth of kale at the baby-leaf harvest stage in a plant factory with artificial lighting (PFAL) by integrating morphological traits, biomass accumulation, plant quality indices, vegetation indices, and chlorophyll a fluorescence. Two kale (Brassica oleracea L.) cultivars, ‘Jellujon’ and ‘Manchoo Collard’, were grown for four weeks under monochromatic red, green, and blue LEDs, a purple composite LED with far-red wavelengths, and three white LEDs with different correlated color temperatures (3000, 4100, and 6500 K). Blue LED increased shoot height by approximately 14–28%, depending on cultivar and comparison among the white LED treatments, but this elongation did not translate into superior biomass production. In contrast, white LEDs, particularly at 3000–4100 K, increased leaf area to 24.2–24.9 cm² and SPAD units to 47.3–50.2, whereas blue or green LEDs generally resulted in smaller leaves and lower SPAD units. Shoot dry weight under 3000–4100 K white LEDs reached 0.25–0.26 g in ‘Jellujon’ and 0.26–0.29 g in ‘Manchoo Collard’, approximately twofold higher than under blue or green LEDs. Compactness, Dickson quality index, root investment ratio, and leaf efficiency index were also more favorable under white LEDs, indicating improved plant sturdiness and structural stability. Green LED light was associated with lower maximum photochemical efficiency (Φ_Po) and greater energy dissipation (Φ_Do and DI_o/RC), whereas photochemical reflectance index and PI_ABS tended to be more favorable under selected white LED treatments, although these responses were partly cultivar- and treatment-dependent. Taken together, among the LED spectral quality treatments tested, 3000–4100 K white LEDs provided the most consistently favorable conditions for producing structurally robust, high-quality kale at the early growth stage in PFAL systems. The purple LED showed partial advantages in leaf development and selected physiological responses, but these effects were less consistent across cultivars and indices. Full article

This study investigated how different LED spectral compositions affect seed germination, early growth, photosynthetic efficiency, and the postharvest quality and microbiological stability of Ipomoea aquatica Forsk. cultivated in a plant factory system, aiming to propose an integrated management strategy for stable year-round production. Five LED light treatments with varying red and blue light ratios (R10, R7B3, R5B5, R3B7, and B10) were applied during cultivation. After harvest, the plants were stored under low-temperature conditions using either carton box packaging or modified atmosphere packaging (MAP) to evaluate postharvest quality and microbial changes. Germination analysis indicated that red-dominant treatments (R10 and R7B3) significantly enhanced germination percentage, rate, and uniformity. These treatments also promoted greater plant height and fresh biomass accumulation during early growth while maintaining a higher maximum quantum yield of photosystem II (Fv/Fm), indicating improved photochemical efficiency. In contrast, blue-dominant treatments led to reduced growth performance and lower Fv/Fm values. Postharvest quality and microbiological stability were more significantly affected by the packaging method than by the LED light treatment. MAP effectively minimized fresh weight loss and inhibited the growth of aerobic bacteria, Escherichia coli, total coliforms, and yeast and mold during storage. Overall, the findings demonstrate that red-centered LED spectra are optimal for enhancing early growth and physiological stability of I. aquatica, while MAP is crucial for preserving postharvest quality and microbial safety. This study underscores the synergistic potential of combining LED spectral management during cultivation with optimized packaging strategies to achieve stable year-round production and extended shelf life of I. aquatica in controlled plant factory systems. Full article

Enhancing selenium (Se) content of aromatic plants addresses micronutrient deficiencies affecting billions. Plants are the primary dietary Se source, so biofortification can enhance Se intake. This study examined the effects of Se biofortification with sodium selenate (5 μM Na₂SeO₄) and moderate salinity stress (10 mM sodium chloride NaCl) on dill (Anethum graveolens L.) grown in a Plant Factory with Artificial Lighting using Nutrient Film Technique (NFT-PFAL) or Floating System (FS-PFAL), and in a Greenhouse with FS (FS-GH). Se biofortification and moderate salinity stress did not affect dill yield in any hydroponic system. Plants under combined Se biofortification and salinity stress (Se + NaCl) showed increased Se concentration in leaves of 31.78 mg kg⁻¹, 33.12 mg kg⁻¹, and 23.32 mg kg⁻¹ in NFT-PFAL, FS-PFAL, and FS-GH, respectively, compared to Se alone. Total phenolics content in leaves increased under Se biofortification with salinity stress across all systems, showing 159.57%, 223.13%, and 82.64% increases over control in NFT-PFAL, FS-PFAL, and FS-GH. Oxidative stress enzymes increased in response to Se, NaCl, and combined treatments across systems. FS-GH showed highest ascorbate peroxidase and guaiacol peroxidase activities, while PFAL systems showed lower but comparable activities. This study demonstrates that combining Se biofortification with moderate salinity stress in hydroponic systems can enhance plant functionality and human nutrition. Full article

Optimizing lighting in plant factory with artificial lighting (PFAL) is essential for balancing lettuce growth and quality. Rapid plant growth in PFAL often induces physiological disorders, especially tipburn, which is associated with calcium deficiency in newly emerging leaves. This study aimed to evaluate the effects of different proportions of green light substitutions on tipburn incidence and the growth of romaine lettuce cultivated in a PFAL. Plants were grown under different proportions of green light at a total light intensity of 200 µmol m⁻² s⁻¹, consisting of 40% (G40), 60% (G60), 80% (G80), and 100% (G100) green light. The results showed that increasing the proportion of green light significantly reduced tipburn incidence from 49% to 25%, while shoot fresh weight declined by 7% and 25% when green light substitution increased to 80% and 100%, respectively. Net CO₂ assimilation of outer leaves remained similar among G40, G60, and G80 but declined by approximately 13% under 100% green light (G100). Higher proportions of green light markedly increased calcium accumulation and chlorophyll content in the inner leaves. These results suggest that higher proportions of green light may improve the inner-leaf light environment, enhance inner-leaf physiological function, and thereby reduce tipburn incidence. Substituting 60% green light achieved a good balance between growth performance and tipburn reduction. This approach offers an effective method to mitigate tipburn and improve lettuce quality in PFALs. Full article

The light environment in a plant factory with artificial light (PFAL) can be determined based on the optical properties of the plants or structural components and lighting design (LD). Although an optimal LD can create the desired light environment, determining it is difficult because it is a complex problem with multiple variables, objectives, and constraints. In this study, we aimed to search for optimal LD using the ray-tracing method for optical simulations and ε-constrained multi-objective differential evolution for optimization. First, the LD of a cultivation system was optimized, and komatsuna plants were cultivated under the optimal LD. The correlation coefficients between the objective functions and corresponding indices calculated from the komatsuna dry weights were larger than 0.75. Therefore, an LD suitable for a specific cultivation purpose can be obtained through optimization. Thereafter, the LD of a virtual cultivation system was optimized. The photosynthetic rate and its uniformity showed a broadly positive correlation, whereas electric energy use efficiency showed trade-off relationships with other objective functions. Therefore, the threshold of electric energy use efficiency could serve as an indicator for selecting a suitable LD. These results demonstrate that LD optimization can be used to suggest optimal LD with concrete values for practical application. Full article

The consumption of edible flowers is gaining global popularity due to their culinary appeal, vibrant colors, and health-promoting compounds. Traditional production methods—including wild collection, open-field cultivation, and greenhouse systems—offer limited control over environmental factors, often resulting in inconsistent yield, quality, and safety. To address these limitations, plant factories with artificial lighting (PFALs) have emerged as a promising technology for producing high-quality edible flowers year-round in controlled environments. This review explores the evolution of edible flower cultivation, from conventional methods to PFALs, and highlights key environmental factors—light, temperature, and nutrient management—that influence growth, flowering, and phytochemical profiles. Special attention is given to how light intensity, spectrum, and photoperiod affect morphogenesis and metabolite accumulation, and how nutrient solution composition, particularly nitrogen form and EC levels, modulates flowering and plant health. While recent studies have demonstrated the potential of PFALs in cultivating species such as calendula, nasturtium, and marigold, research remains limited for many commercially relevant species. The review identifies current challenges, such as high operational costs and knowledge gaps in species-specific protocols, and outlines future research directions aimed at improving efficiency, optimizing quality, and expanding market viability. PFALs offer a transformative opportunity for the edible flower industry by integrating precision agriculture with consumer demand for safe, functional, and visually appealing food products. Full article

Developing environmentally friendly and cost-effective substrates is critical to enhance resource efficiency and productivity in plant factories with artificial lighting (PFALs). This study employed a molded coconut coir substrate (coconut coir composited with polyurethane hydrophilic adhesive, MCCS) in PFALs to cultivate lettuce (Lactuca sativa L.) and pak choi (Brassica rapa ssp. chinensis). During the transplanting stage, the roots exposed outside the MCCS of lettuce and pak choi were 13.40% and 19.92% shorter, respectively, than in the sponge treatment, and more amenable to mechanical transplanting. This compensated for the neglect of operational efficiency in traditional lifecycle assessment (LCA). Furthermore, compared with sponge and rockwool, MCCS significantly enhanced the yield of lettuce and pak choi by up to 27.33% and 67.19%, respectively. Meanwhile, MCCS significantly increased the chlorophyll content of lettuce compared to sponge by 8.56%. Compared with rockwool, MCCS significantly increased the chlorophyll b content (7.36%), antioxidant content, and antioxidant activity (total phenolics by 13.59%, total flavonoid by 18.43%, FRAP by 12.96%, and DPPH by 19.87%) of lettuce. For pak choi, MCCS increased the soluble protein content in the blade and total phenolics content in the petiole by 32.01% and 14.76%, respectively. More importantly, the use of MCCS led to a significant reduction in the energy consumption per unit area yield of lettuce and pak choi, with maximum reductions of 22.98% and 40.91%, respectively. This eco-friendly substrate is suitable for replacing sponge and rockwool in the production of lettuce and pak choi in PFALs. Full article

Calendula (Calendula officinalis L.), an edible and medicinal flower, faces challenges in yield uniformity and quality stability under open-field cultivation. Plant factories with artificial lighting (PFALs) are highly controlled systems that enable year-round production, efficient resource use, and consistent crop quality, making them promising for the cultivation for calendula. To optimize calendula cultivation in PFALs, this study investigates the effects of far-red (FR) light and nutrient solution modification on calendula growth, flowering, and nutrient use efficiency (NUE). The experiment was conducted using a dwarf calendula cultivar, ‘Orange Gem’. After transplanting, seedlings were subjected to a 2 × 3 factorial design comprising white (W) and end-of-day far-red (EOD-FR) lighting, in combination with three ammonium (NH₄⁺) levels (1/3×, 1×, and 3× of the Enshi formula). The EOD-FR lighting and the increase in the NH₄⁺ level resulted in taller plants and earlier first flower appearance. The shoot fresh and dry weight, the number of flowers, and the flower yield also increased under the higher NH₄⁺ concentration, regardless of the light treatment. The 3× NH₄⁺ treatment tended to enhance the nutrient absorption, leading to the highest nutrient use efficiency (NUE) based on the flower yield. These findings suggest that the application of EOD-FR lighting and high NH₄⁺ in nutrient solution can improve calendula productivity and resource-use efficiency in PFALs. Full article

Indoor farming in plant factories with artificial lighting (PFAL) offers optimized growing conditions and higher water, light, and land surface use efficiencies compared to greenhouses or open field agriculture but faces challenges related to energy consumption. The objective of this work is to evaluate the feasibility of using a rotational cultivation system for indoor-grown lettuce production. We compare a rotational cultivation system to a horizontal control cultivation system in terms of yields, resource efficiency, quality at harvest, and postharvest storage capacity. No significant differences were observed in yields, water use efficiency, light use efficiency, or postharvest storage capacity between the systems. Energy and land surface use efficiencies were higher in the rotational cultivation system compared to the control and consistent with the literature. However, a slight trend toward lower fresh and dry weights throughout the cultivation period in the rotational system was noted, correlating with reduced net photosynthesis during the first two hours and at the end of the lighting period. This effect was attributed to decreased stomatal conductance and photosystem II efficiency. Furthermore, the rotational cultivation system modified the quality by modifying the global polyphenol profile of the lettuce compared to the control. Based on yields and efficiencies, we show the feasibility of using a rotational cultivation system for indoor lettuce production. Full article

Innovation in cultivation methods is essential to address the growing challenges in agriculture, including abiotic and biotic stress, soil degradation, and climate change. Aeroponics, a particular type of hydroponics, presents a promising solution by improving yield and resource use efficiency, especially in controlled environments such as plant factories with artificial lighting (PFALs). Additionally, non-thermal plasma (NTP), a partially ionized gas containing reactive oxygen and nitrogen species, can affect plant development and physiology, further enhancing crop production. The objective of this study was to explore the potential of NTP as an innovative method to enhance crop production by treating the nutrient solution in aeroponic systems. During this study, three experiments were conducted to assess the effects of NTP-treated nutrient solutions on baby leaf lettuce (Lactuca sativa L.) aeroponically grown indoors. The nutrient solution was treated with ionized air in a treatment column separated from the aeroponic system by making the ionized air bubble from the bottom of the column. After 2 min of NTP application, a pump took the nutrient solution from the treatment column and sprayed it on the roots of plants. Various frequencies of NTP application were tested, ranging from 2.5% to 50% of irrigation events with nutrient solution activated with NTP. Results indicated that low-frequency NTP treatments (up to 5% of irrigations) stimulated plant growth, increasing leaf biomass (+18–19%) and enhancing the concentration of flavonoids (+16–18%), phenols (+20–21%), and antioxidant capacity (+29–53%). However, higher NTP frequencies (25% and above) negatively impacted plant growth, reducing fresh and dry weight and root biomass, likely due to excessive oxidative stress. The study demonstrates the potential of NTP as a tool for improving crop quality and yields in aeroponic cultivation, with optimal benefits achieved at lower treatment frequencies. Full article

Plant factories with artificial lighting (PFALs) are a notable choice for urban agriculture due to the system’s benefits, where light can be manipulated to enhance the product’s yield and quality. Our objective was to test the effect of light spectra with different red-blue combinations and white light on the growth, physiology, and overall quality of three baby-leaf vegetables (green lettuce, kale, and pak choi) grown in a restaurant’s PFAL. Leaf mass per area was lower under the most blue-containing treatments in all species. The performance indices (PI_abs and PI_tot) of the photosynthetic apparatus were lower under more red light with the exception of PI_abs in pak choi. Total soluble solids accumulation was diminished under most of the blue-containing LEDs, while total phenolics and antioxidant activity were induced by red-blue environments rich in blue light. Moreover, chlorophyll and carotenoid accumulation was also enhanced under blue-rich light treatments. Nitrate content was the lowest under monochromatic blue in all species. Finally, the employees were asked about their views on the PFAL within the restaurant’s compounds and they expressed positive opinions. Overall, a light environment including red and blue wavelengths proved beneficial for baby leafy vegetable production in terms of yield and quality. Full article