We evaluated the effect of a newly-developed nutrient solution of red perilla (NSP) with various electrical conductivity (EC) levels on plant growth, mineral content, and bioactive compounds. Four-week-old seedlings were grown in greenhouse nutrient solution as control (CT) (EC 1–3 dS m⁻¹) or NSP (EC 1–6 dS m⁻¹). NSP 1 dS m⁻¹ induced better growth characteristics, whereas higher EC levels inhibited plant growth. Most of the macro-elements contents significantly decreased under NSP 6 dS m⁻¹, whereas the micro-elements contents fluctuated according to EC levels. Total phenolic concentration in NSP was lower than that in CT, and total phenolic content was highest under NSP 1 dS m⁻¹. Total anthocyanin and antioxidant concentrations and contents increased at lower EC levels. Rosmarinic and caffeic acids concentrations increased at higher EC levels, whereas there were no significant differences in these compound contents among the EC levels. No difference in perillaldehyde concentration was observed, whereas the content was higher at lower EC levels. Overall, these results suggest that NSP 1 dS m⁻¹ is suitable for cultivating red perilla in plant factories.

The medicinal plant, coastal glehnia (Glehnia littoralis F. Schmidt ex Miq.), belongs to the Apiaceae, which is known to exhibit morpho-physiological seed dormancy (MPD). In this study, we aimed to determine the dormancy type of this plant, along with the conditions for breaking dormancy, and how to increase its germination rate for mass production. Initially, the seeds of coastal glehnia had undeveloped embryos, which gradually developed following cold (5 °C) stratification over eight weeks. The embryo to seed (E:S) ratio increased to 66.7%, confirming that the seeds had the MPD type. Coastal glehnia seeds with pericarp did not show inhibited water uptake, and the germination inhibitory chemicals were not detected. However, removal of the pericarp improved the final germination percentage, germination speed, and T₅₀ of coastal glehnia seeds compared with those of seeds with pericarp at 20 °C, which showed the highest value compared with other temperature treatments. Thus, cold stratification at 5 °C for eight weeks and removing the pericarp of germinating seeds maintained at 20 °C is efficient ways to break dormancy and improve the germination rate for the mass production of coastal glehnia.

Achyranthes japonica Nakai (AJN) is a medicinal plant known to be beneficial for the joints. Since it takes at least two years from sowing to harvesting in an open field, new AJN cultivation strategies are needed to shorten the production period and improve quality. In this study, high-quality AJN is produced as microgreens in a vertical farm using a commercial ginseng soil mix (Myeongpum-Insamsangto, Shinsung Mineral Co., Ltd., Goesan, Republic of Korea) and controlled environmental conditions. The cultivation conditions included a temperature of 23 ± 2 °C, relative humidity of 50 ± 10%, and a photosynthetic photon flux density of 170 ± 15 µmol·m⁻²·s⁻¹. Pre-harvest intermittent UV-B exposure, with an intensity of 1.0 ± 0.3 W/m⁻², was applied for one day before harvest to evaluate its effects, using controlled environmental conditions in the vertical farm. Ultraviolet-B (UV-B) irradiation increases secondary metabolite levels in plants; however, the effect of UV-B on 20-hydroxyecdysone (20E), an indicator of AJN, is unclear. Therefore, we aimed to investigate whether UV-B treatment of AJN microgreens affected growth and secondary metabolites. The treatment group was set to 12 h of continuous UV-B treatment during the day, two 6 h UV-B treatments, and four 3 h UV-B treatments to confirm the effectiveness of regular and intermittent treatment and recovery. Short-term UV-B treatment before harvesting increased phenols, flavonoids, antioxidant capacity, and 20E levels without affecting AJN biomass. The intermittent 6 h UV-B irradiation with a 6 h recovery time stimulated 20E content by approximately 1.4 times compared to the control. These study findings indicate that short-term UV-B treatment before harvesting, an appropriate recovery time, and intermittent UV-B exposure are more effective at increasing 20E content than continuous treatment. This approach provides a promising strategy for improving the nutritional and health benefits of AJN microgreens in vertical farming systems.

This study was conducted to develop a nutrient solution for coastal glehnia, evaluate the performance of the newly developed nutrient solution, and determine an adequate electrical conductivity (EC) level for growth and bioactive compounds production in controlled environment agriculture (CEA). Coastal glehnia plants cultivated in Hoagland nutrient solution with EC 1, 2, 3, 4, and 5 dS·m⁻¹ for 20 weeks had the same ratio of cations and anions in terms of macro essential elements. Based on the ratio, a new nutrient solution for coastal glehnia was developed. Subsequently, seedlings with two main leaves were grown in Hoagland nutrient solution (H1 and H2; EC 1 and 2 dS·m⁻¹) or a newly developed nutrient solution (N1–5; EC 1–5 dS·m⁻¹) for 23 weeks (about 6 months), and the leaves were harvested every 5 weeks. The N1 treatment resulted in significantly higher accumulated and average shoot fresh and dry weights than in the H1 and H2 treatments. In addition, the total phenolic content and antioxidant capacity per shoot were the highest under the N1 treatment. Individual bioactive compounds, such as xanthotoxin, bergapten, and imperatorin, levels per shoot with the N1 treatment were significantly higher than those with the H1 and H2 treatments. These results demonstrate that the newly developed nutrient solution of EC 1 dS·m⁻¹ increases the biomass and bioactive compound levels of coastal glehnia and is suitable for cultivating coastal glehnia in CEA, such as vertical farms and greenhouses.

Environmental control in crop production typically relies on real–time sensor data to monitor environmental conditions. However, the data does not reflect the immediate physiological status of crops, limiting the precision of crop-based environmental management. To enhance crop productivity, quality, and resource use efficiency, it is necessary to collect direct information about crop health status and reflect this in crop–specific environmental control. Plant electrical signals, which reflect physiological responses to external environment, can be used as biosensors for crop health. Here, electrical signals from lettuce seedlings were measured under different temperature and lighting conditions. Machine learning techniques were applied to both raw and extracted feature signals to classify the electrical responses to each environmental parameter. Lettuce seedlings were exposed to different air temperature conditions, with and without light. The electrical signals were detected through electrode needles inserted into the stems of the seedlings under each condition. Gaussian smoothing, moving average, and peak–to–peak methods were used to remove noise from raw electrical signals and extract the features, which were then used in a machine learning model to classify the temperature and light environments. The results showed that decision tree model achieved high F1 scores of 0.9778 for temperature and 0.9316 for lighting conditions. Additionally, evaluating the generalisation performance of the model by adding another lettuce variety resulted in F1 scores confirmed the robustness of model. These findings suggest that plant electrical signals can be used to monitor crop health in complex environments, offering the potential for more precise environmental management in crop production.