The plant factory with artificial light (PFAL) is a novel cultivation system of agriculture technology for crop production under controlled-environment conditions. However, there are a number of issues relating to low quality of seed germination and seedling vigor that lead to decreased crop yields. The present study investigates the optimal KNO₃ concentration for seed germination, and the influence of different light spectra on early plant growth in holy basil (Ocimum tenuiflorum) under a PFAL system. Experiment 1 investigated the effects of KNO₃ concentration (0, 0.2, 0.4 and 0.6%) on germination of seeds primed for 24 h under white Light emitting diodes (LED). Results show that sowing holy basil seeds in 0.4% KNO₃ enhanced seed germination percentage (GP) and germination index (GI), while decreasing mean germination time (MGT). Experiment 2 investigated the effect of four light spectra on seed germination and early plant growth by sowing with 0 and 0.4% KNO₃ and germinating for 15 days continuously under different monochromatic light settings: white, red, green and blue in PFAL. It was found that the green spectrum positively affected shoot and root length, and also decreased shortened MGT at 0 and 0.4% KNO₃ when compared with other light treatments. Additionally, pre-cultivated seedlings under the green spectrum showed significant improvement in the early plant growth for all holy basil varieties at 15 days after transplanting by promoting stem length, stem diameter, plant width, fresh weights of shoot and root, and dry weights of shoot and root. These findings could be useful in developing seed priming and light treatments to enhance seed germination and seedling quality of holy basil resulting in increased crop production under PFAL.

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.

Radish (Raphanus sativus L.) is highly nutritious and contains antioxidants that help reduce the risk of diseases. Light is a crucial factor in their growth and the stimulation of secondary metabolite production. Therefore, this study aimed to investigate the effects of light spectra on the development, physiological responses, and antioxidant capacity of radish varieties including cherry belle (CB), black Spanish (BS), hailstone white (HW), Malaga violet (MV), and sparkler white tip (SW) under a controlled environment. Various spectra of red (R), green (G), and blue (B) light were used. The study found that using a combination of red and blue light (3R:1B) resulted in the highest growth in root diameter, fresh weight, and dry weight across all five radish varieties, with values ranging from 1.83 to 4.63 cm, 13.58 to 89.33 g, and 1.20 to 4.64 g, respectively. In terms of physiological responses, the CB and BS varieties showed a higher photosynthetic rate after exposure to mixed red and blue light (1R:3B, 3R:1B). Additionally, adding green light to the red and blue light also enhanced the photosynthetic rate, with statistically significant differences ranging from 3.31 to 3.99 µmol m⁻² s⁻¹. The SW variety of radish exhibited an increase in phenolic compounds, flavonoids, and anthocyanins when exposed to light spectra of 1R:1G:1B, 1R:2G:1B, 1R:3G:1B, and 1R:3B. The highest levels of phenolic compounds were 4.67–5.14 mg GAE/g DW, flavonoids were 1.62–1.96 mg Rutin/g DW, and anthocyanins were 1.20–1.58 µg/g DW. However, the antioxidant capacity of five radish varieties under different light spectra did not show significant differences. Thus, the growth, photosynthesis, and antioxidant capacity depend on the optimal light spectrum for each radish variety.

The growing media is one of the significant elements affecting microgreens’ yield and quality. This experiment investigated the possibility of waste utilization instead of employing peat moss to produce sunflower and water-spinach microgreens. The treatments consisted of peat moss (Control), coconut coir dust (CD), leaf compost (LC), food waste compost (FC), CD:LC = 1:1 v/v, CD:FC = 1:1 v/v, LC:FC = 1:1 v/v, and CD:LC:FC = 1:1:1 v/v. The results proved that the highest yield of sunflower microgreens was observed when cultivated in 1:1 v/v of CD:LC media (10,114.81 g m⁻²), whereas the highest yield of water spinach microgreens was recorded under the treatments of CD, Control, 1:1 v/v of CD:LC, and 1:1:1 v/v of CD:LC:FC media (10,966.67–9800.00 g m⁻²). The biochemical composition of the microgreens varied within the types. Our findings demonstrated that a tendency of an increase in chlorophyll and carotenoid contents depended on the growth of both microgreens under different growing media. All growing media did not cause excess nitrate residue or pathogenic contamination in both microgreens, namely Clostridium perfringens, Salmonella spp., and Staphylococcus aureus. In contrast, almost all the growing media resulted in a higher population of Bacillus cereus contamination in both microgreens than the standard set limit, except for sunflower microgreens grown in the control and CD growing media. These findings could suggest that the 1:1 v/v of CD:LC and CD media were the most effective growing media for sunflower and water spinach microgreens, respectively, but further cleaning before consumption is recommended to avoid or reduce the foodborne incidences caused by B. cereus in microgreens.

Agricultural practice in adjusting planting density and harvest date are important factors for plant development and crop improvement, reaching maximum yields and enhancing the production of secondary metabolites. However, it is unclear as to the optimal planting densities during mass production that encourage consistent, high yield secondary metabolite content. For this, controlled environment, crop production facilities such as plant factories with artificial lighting (PFAL) offer opportunity to enhance quality and stabilize production of herbal plants. This study assessed the effect of plant density and harvest date on physiological responses, yield and andrographolide (AP1) content in Andrographis paniculata (Andrographis) using hydroponic conditions in a PFAL system. Andrographis, harvested at vegetative stage (30 days after transplanting; 30 DAT) and initial stage of flowering (60 DAT) exhibited no significant differences in growth parameters or andrographolide accumulation according to planting densities. Harvest time at flowering stage (90 DAT) showed the highest photosynthetic rates at a planting density of 15 plants m^-2. Highest yield, number of leaves, and Andrographolide (AP1) content (mg per gram of DW in m²) were achieved at a more moderate planting density (30 plants m^-2). Finally, five out of seventeen indices of leaf reflectance reveal high correlation (r = 0.8 to 1.0 and r = -0.8 to -1.0, P<0.01) with AP1 content. These results suggest that a planting density of 30 plants m^-2 and harvest time of 90 DAT provide optimal growing condition under the hydroponic PFAL system.

Hericium erinaceus (Bull.:Fr) Pers. is a medicinal mushroom that has various health benefits and is a rich source of bioactive compounds and antioxidant activity. In recent years, H. erinaceus has been considered for its many medicinal properties and is widely consumed in Asian countries. This work aimed to explore the potential improvement of coconut water utilization in order to promote growth and increase the yield, as well as the enhancement of bioactive compounds and antioxidant activity of H. erinaceus. The application of coconut water at a concentration of 20% (v/v) resulted in the optimal development and production of H. erinaceus. In terms of biological efficiency, it was demonstrated that the 22.09% increase over the control treatment resulted in a higher yield. Moreover, H. erinaceus cultivated from coconut water intake at all concentrations resulted in higher protein content. Additionally, bioactive compounds such as total triterpenoid content and total phenolic content of H. erinaceus were 67.87–89.24 mg Urs/g DW and 16.62–17.39 mg GAE/g DW, respectively, while H. erinaceus grown on a control treatment had the lowest at 56.84 mg Urs/g DW and 14.42 mg GAE/g DW, respectively. Applying coconut water at all concentrations resulted in H. erinaceus IC₅₀ values of 0.58–0.69 mg/mL exhibiting higher DPPH activities than those grown on control treatment IC₅₀ value of 0.77 mg/mL. Therefore, this finding of the study indicated that the utilization of coconut water as a therapy resulted in a significant enhancement in the development, production, and bioactive compounds of H. erinaceus, in comparison to the control treatment.