Light-emitting diodes (LEDs) are an artificial light source used in indoor cultivation to influence plant growth, photosynthesis performance and secondary metabolite synthesis. Holy basil plants (Ocimum tenuiflorum) were cultivated under fully controlled environmental conditions with different red (R) and blue (B) light intensity ratios (3R:1B, 1R:1B and 1R:3B), along with combined green (G) LED (2R:1G:2B). The photosynthetic activities of both cultivars were maximal under 3R:1B. However, the highest fresh (FW) and dry (DW) weight values of green holy basil were recorded under 3R:1B and 2R:1G:2B, significantly higher than those under alternative light conditions. For red holy basil, the highest FW and DW were recorded under 1R:3B. Moreover, 2R:1G:2B treatment promoted pigment (chlorophyll and carotenoid) accumulation in green holy basil, while red holy basil was found to be rich in both pigments under 3R:1B. Antioxidant capacity was also influenced by light spectrum, resulting in greater total phenolic content (TPC) and DPPH accumulation in both cultivars under 1R:3B. The highest content of flavonoid in green holy basil was detected under 1R:1B; meanwhile, 1R:3B treatment significantly promoted flavonoid content in red holy basil. In addition, anthocyanin content increased in red holy basil under 1R:3B conditions. Gas chromatography coupled with mass spectrometry (GC–MS/MS) analysis of chemical composition showed higher proportional accumulation in Methyleugenol and Caryophyllene of two cultivars grown under all light spectrum ratios at two developmental stages. Overall, specific light spectrum ratios induced different chemical composition responses in each cultivar and at each developmental stage. These results suggest that 3R:1B was favorable for biomass accumulation and photosynthetic responses in green holy basil, while 1R:3B provided antioxidant accumulation. For red holy basil cultivation, 1R:3B provided optimal growing conditions, promoting improvements in plant biomass, and physiological and antioxidant capacities.

Cultivating red oak lettuce in plant factories often encounters challenges in achieving the desired red leaf coloration. To make the leaves a pleasant red color, anthocyanins are key substances that need to be induced. This study aimed to evaluate the effects of increasing light intensity and irrigation methods on the growth and leaf color of red oak lettuce in a controlled environment. Two light intensities (300 and 400 µmol m⁻² s⁻¹) with white LEDs and two irrigation methods (circulating vs. non-circulating irrigation) were applied seven days before harvesting. The results indicated that plants grown with circulating irrigation exhibited significantly higher fresh and dry weights than those grown under non-circulating conditions, regardless of light intensity. When non-circulating irrigation was applied, shoot fresh weight decreased by approximately 22% on the harvesting day compared to the circulating treatments. Under the 400 µmol m⁻² s⁻¹ light intensity with non-circulating irrigation (400N-C), plants displayed the lowest lightness (L*) at 40.7, increased redness (a*) to −7.4, and reduced yellowness (b*) to 11.0. These changes in coloration were optimized by day 5 after treatment. Additionally, spectral indices, including normalized difference vegetation index and photochemical reflectance index, varied significantly among treatments. The 400N-C treatment also resulted in the highest anthocyanin content and antioxidant activity in red oak lettuce. These findings suggest that combining high light intensity with non-circulating irrigation before harvest can improve both the coloration and quality of red oak lettuce in plant factories with artificial lighting.

Holy basil (Ocimum tenuiflorum L.) is an extensively utilized herb, encompassing numerous bioactive compounds that hold significant interest in the food and pharmaceutical industries. High-throughput phenotyping is a rapid and non-invasive technique, providing diverse phenotypic trait observation and measurement. However, basic knowledge regarding the diversity among varieties beneficial for large-scale production in terms of yield and secondary metabolites under a controlled greenhouse environment is limited. Hence, we assessed and classified 12 Thai accessions and two commercial cultivars by evaluating growth, yield, and secondary metabolites at each harvesting time using an advanced NSTDA-Plant Phenomics platform. Notably, accessions OC130, OC141, OC072, and OC059 demonstrated stable metabolite production and antioxidant activity, highlighting their potential as superior accessions for further cultivation and utilization. These findings underscore the potential for tailored cultivation practices to manipulate secondary metabolite synthesis, thereby enhancing the medicinal properties and market value of Thai holy basil. The implications of this study extend to farmers, providing valuable insights into the phenotypic variation and practical avenues under consistent environmental conditions. Breeders can observe genetic diversity to improve basil varieties with desirable traits for specific environmental niches. Moreover, modern agricultural practices can benefit from understanding the impact of controlled environments on secondary metabolite synthesis.

Light spectrum is a crucial environmental factor influencing plant growth and secondary metabolite production in controlled-environment agriculture. This study investigated the combined effects of light spectral composition on growth performance and andrographolide accumulation in Andrographis paniculata (Burm.f.) cultivated in a plant factory system. Two Thai cultivars, RBR and TTT, were grown under white light and various red–green–blue (R:G:B) LED ratios during the vegetative and flowering stages. Plant morphological traits, biomass accumulation, and andrographolide derivatives (AP1, AP4, AP6, and total AP) were quantified. Growth and biomass production were significantly enhanced under white light and red-enriched spectra, particularly during the vegetative stage, whereas stem elongation exhibited reduced sensitivity to light spectral quality during the flowering stage. In contrast, andrographolide accumulation showed a strong cultivar-dependent response to light spectrum. The TTT cultivar showed pronounced increases in AP1, AP4, AP6, and total AP under blue-enriched spectra, with the 60B:10G:30R treatment producing the highest total diterpenoid content in both cultivars, while the RBR cultivar displayed limited responsiveness to spectral variation. These results demonstrate light spectrum affecting both biomass production and phytochemical accumulation. Optimization of light spectral composition combined with appropriate cultivar selection offers an effective strategy for enhancing pharmaceutical-grade andrographolide production in plant factory systems.