White (W) light-emitting diode (LED) light has been used as an efficient light source for commercial plant cultivation in vertical farming. This study aimed to examine the effect of W LED light sources on the growth and quality of butterhead and romaine lettuce. Three W LED light sources including normal W light (NWL) which has 450 nm as its pumping wavelength and two specific W lights (SWL1 and SWL2) with shorter blue peak wavelength (437 nm) were used to grow lettuce in comparison to a red (R) and blue (B) LED combination. As a result, SWL1 and SWL2 treatments with the same electrical power or photosynthetic photon flux density (PPFD) resulted in more growth of both lettuce cultivars compared to RB treatment. Some phenolic and flavonol contents were increased in the RB treatment, whereas SWL2 treatment stimulated the accumulation of other phenolic and flavonol compounds. Meanwhile, neither NWL nor SWL1 treatments increased the individual phenolic and flavonol contents in either cultivar (except for some flavonols in romaine lettuce in the SWL1 group). In addition, light and energy use efficiencies were also highest in the SWL1 and SWL2 treatments. These results illustrate the positive effects of specific W LED light on lettuce growth and quality, and suggest that the specific W LED light sources, especially SWL2, could be preferably used in vertical farming.

In this study, the primary (such as amino acids, fatty acids, and minerals) and secondary (including ginsenosides, phenolic acids, and flavonols) metabolites and antioxidant effects of Panax ginseng sprouts (PGSs) by different cultivation systems, such as soil–substrate cultivation (SSC) and deep-water cultivation (DWC), in a plant factory has been observed. There was no significant difference in the total fatty acid (FA) contents. Particularly, the major FAs of PGSs were palmitic acid (207.4 mg/100 g) of saturated FAs and linoleic acid (397.6 mg/100 g) and α-linolenic acid (222.6 mg/100 g) of unsaturated FAs in the SSC system. The values of total amino acids were all higher in SSC than in DWC. In the case of ginsenosides, the total protopanaxtriol product was 30.88 mg/g in SSC, while the total protopanaxdiol product was 34.83 mg/g in DWC. In particular, the values of total phenolic acids and total flavonols were 133.36 and 388.19 ug/g, respectively, and SSC had a higher content than DWC. In conclusion, the SSC system was shown to be higher in nutritional constituents and antioxidant activities in soil cultivation, suggesting that PGS with SSC has a positive effect on the quality of PGS in a plant factory.

This study analyzed growth patterns, biological compounds, antioxidant properties, ginsenoside contents, metabolites, and the annual net production of ‘Yunpoong’ and ‘K-1’ to find the optimal harvesting time of ginseng sprouts. One-year-old ginseng seedlings were cultivated in a container-type vertical farm under a temperature of 20 °C, a humidity of 60%, and average light intensity of 46.4 µmol m⁻² s⁻¹ (16 h photoperiod). Growth patterns at 2, 3, 4, and 5 weeks after transplanting (WAT) differed between cultivars. Regarding biological compounds and antioxidant properties, ‘Yunpoong’ took 5 WAT (43.59%; 2,2-diphenyl-1-picryl-hydrazine-hydrate radical scavenging activity, 1.47 OD_593nm; ferric reducing antioxidant power assay, 78.01%; 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activity), and ‘K-1’ took 4 WAT (0.98 Re mg g⁻¹; total flavonoid contents, 35.93%; DPPH) to show a high content. Two cultivars showed the highest total ginsenoside contents at 5 WAT. Most of the analyzed metabolites had a higher content in ‘Yunpoong’ than in ‘K-1’. In both cultivars, it was confirmed that the longer the growth period (3 − > 5 WAT), the lower the yield and the annual ginsenoside net production. Therefore, ‘Yunpoong’ and ‘K-1’ cultivars should be grown as ginseng sprouts in the vertical farms for approximately 3 WAT and 4 WAT, respectively.

Low root-zone temperatures (RZTs) are known to cause various physiological changes in plants, which ultimately result in reduced overall plant growth and productivity. However, the effects of temperature on the below-ground parts remain largely unknown; a notable gap exists in understanding the effects of low RZTs on plants. Therefore, we explored the impact of short-term root-zone temperature cooling (RZTC) on the growth, physiological responses, and amino acid levels of Taraxacum coreanum in hydroponic systems. We also investigated the monoamine oxidase (MAO) inhibitory activity of T. coreanum leaves and roots following RZTC treatment. T. coreanum roots were exposed to low-temperature nutrient solutions over 5 days to cool the root zone at 53 days after sowing. RZTC treatments included gradual cooling (GC), with temperatures gradually decreasing from 15 to 5 °C for 5 days, and rapid cooling (RC), in which roots were exposed to 5 °C for 5 days. RZTC caused a decrease in total amino acid content, except for glutamic acid and proline in T. coreanum leaves. In roots, the RC treatment significantly increased proline and glutamine, with glutamine exhibiting the most significant changes, thus increasing total amino acids. MAO inhibition assays indicated improved activity in both leaves and roots following RZTC treatments, with RC enhancing the inhibitory effects to a greater extent than GC treatment. Therefore, exposing the roots of T. coreanum to 5 °C for 5 days can result in roots with high glutamine content and leaves and roots with improved inhibition rates against MAO.