This study investigates the development and application of an automatic irrigation system based on hourly cumulative evapotranspiration (ET) to optimize cabbage growth while reducing agricultural water usage. Traditional irrigation methods often result in inefficient water use due to reliance on human judgment or fixed schedules. To address this issue, the proposed system utilizes environmental data collected from a field sensor (FS), the Korea meteorological administration (KMA), and a virtual sensor based on a machine learning model (ML) to calculate the hourly ET and automate irrigation. The ET was calculated using the FAO 56 Penman–Monteith (P-M) ET_o. Experiments were conducted to compare the effectiveness of different irrigation levels, ranging from 40, 60, 80, and 100% crop evapotranspiration (ET_c), on plant growth and the irrigation water productivity (WP_I). During the 46-day experimental period, cabbage growth and WP_I were higher in the FS and KMA 60% ET_c levels compared to other irrigation levels, with water usage of 8.90 and 9.07 L/plant, respectively. In the ML treatment, cabbage growth and WP_I were higher in the 80% ET_c level compared to other irrigation levels, with water usage of 8.93 L/plant. These results demonstrated that irrigation amounts of approximately 9 L/plant provided the optimal balance between plant growth and water conservation over 46 days. This system presents a promising solution for improving crop yield while conserving water resources in agricultural environments.

This study aimed to explore the possibility of exogenous ethanol treatment as a technology to regulate the growth and the synthesis of secondary metabolites in herbaceous plants. After transplantation, sweet basil, Korean mint, and sweet wormwood were cultivated in a controlled vertical farming system and consistently exposed to exogenous ethanol at concentrations of 0, 0.5, 1, 2, 4, and 8 mM. Their growth parameters, antioxidant activity, and secondary metabolite contents were Everything is fine. measured to investigate the effects of the exogenous ethanol treatment on the three plants. The low-concentration ethanol treatments increased the shoot dry weight of the sweet basil and sweet wormwood compared to that of the control. As the ethanol concentration increased, the shoot fresh weight and leaf area in the sweet basil and Korean mint decreased compared to those of the control (0 mM). The DPPH (2,2-Diphenyl-1-picrylhydrazyl) radical scavenging activity and total phenolic content of the three plants increased with the ethanol concentration, while the total flavonoid content did not demonstrate a significant trend. The chlorophyll and carotenoids of the basil showed no apparent concentration-dependent trends; however, the chlorophyll and carotenoids of the Korean mint and sweet wormwood decreased with high ethanol concentrations. Moreover, the antioxidant enzyme activity increased with high ethanol concentrations, indicating that high ethanol concentrations induce oxidative stress in plants.

Hemp (Cannabis sativa) has gained global attention since being legalized in the USA in 2018. The legalization of hemp is also underway in Korea; however, it requires facility cultivation and an agricultural technological system that can produce high-quality plants. This study investigated the changes in the growth and secondary metabolite content of female hemp following treatment with the plant growth retardant diniconazole (DIN). Treatment with DIN decreased the plant growth rate with increasing concentrations; however, at a concentration of 25 mg∙L⁻¹, it increased inflorescence biomass and apical inflorescence size. The high-performance liquid chromatograph analysis of major cannabinoids showed no statistically significant differences in total cannabidiol (CBD) and Δ9-tetrahydrocannabinol (Δ9-THC) contents among the treatment groups (25, 50, 100, 200, and 400 mg∙L⁻¹). However, the calculated production of CBD and THC per plant was significantly highest at DIN 25 mg∙L⁻¹. Overall, at a concentration of 25 mg∙L⁻¹, DIN treatment not only decreased the height of female hemp but also enhanced the production of female hemp inflorescences as well as major cannabinoids (CBD and Δ9-THC). Our results indicate that at a concentration of 25 mg∙L⁻¹, DIN is suitable for use in a vertical farming system. However, the Δ9-THC content needs to meet the 0.3% standard for industrial use. These findings can be applied in various fields that use hemp.

This study was conducted to determine the optimal temperature difference in day–night indoor cultivation conditions to enhance the flower yield and functional component contents of female hemp plants. Hemp clones were cultivated under five distinct day and night temperature differences (DIF) during the reproductive stage. The daytime and nighttime temperature settings were as follows: 18:30 °C (negative 12 DIF), 21:27 °C (negative 6 DIF), 24:24 °C (0 DIF), 27:21 °C (positive 6 DIF), and 30:18 °C (positive 12 DIF). Seven weeks after transplantation, the growth parameters, leaf gas exchange, total phenolic compounds, 2,2-diphenylpicrylhydrazyl scavenging activity, and cannabinoid contents were analyzed. The total shoot biomass based on dry weight was highest at 21:27, reaching 41.76 g, and lowest at 30:18, measuring 24.46 g. However, the flower biomass, which is the primary production site, was highest at 24:24 and lowest at 18:30, showing a 4.7-fold difference. The photosynthesis-related parameters were temperature-dependent and strongly correlated with biomass production. The cannabinoid content of the hemp leaves increased at 21:27, whereas that of the hemp flowers increased at 27:21. The findings of this study indicate that the optimal temperature condition for female hemp flower production in a limited space is positive 6 DIF treatment, which corresponds to 27:21 °C. These results can contribute to advancements in indoor crop cultivation technology.

Cannabis sativa, a versatile plant containing over 150 cannabinoids, is increasingly valued for its medicinal properties. It is classified into hemp and marijuana based on its Δ9-tetrahydrocannabinol (Δ9-THC) content. The objective of this study was to optimize cannabinoid production in hemp within a vertical farming system by investigating the effects of methyl jasmonate (MeJA) on plant growth and specific cannabinoid contents. After propagating hemp plants, they were treated with various concentrations of MeJA (0, 100, 200, and 400 μM). Plant growth parameters, glandular trichome (GT) density, and the contents of specific cannabinoids—cannabidiolic acid (CBDA), cannabidiol (CBD), tetrahydrocannabinolic acid (THCA), and Δ9-THC—were analyzed. The results showed that MeJA treatment decreased plant height and leaf area while increasing GT density and the synthesis of CBDA and THCA at lower concentrations. Specifically, treatment with 100 μM MeJA provided optimal conditions for enhancing cannabinoid production while controlling plant height, which is advantageous for vertical farming. These findings suggest that precise application of MeJA in controlled environments can increase yields of valuable cannabinoids with efficient use of space, thereby enhancing the commercial and medicinal value of hemp.