Supplemental Light Differentially Regulates Indoor-Grown Basil (Ocimum basilicum) Growth, Volatile Compounds, and Sensory Attributes

Basil (Ocimum basilicum), a widely cultivated herb, thrives in controlled environment agriculture (CEA) systems where light spectra can be precisely manipulated to optimize growth, morphology, and chemical composition. This study examined the effects of supplemental blue (BL), green (GR), and far-red (FR) light on two basil cultivars, green Prospera and purple Amethyst, focusing on plant growth, photosynthetic efficiency, volatile compound profiles, and sensory attributes. The results showed that FR light significantly increased stem elongation and biomass accumulation, with stem height increasing by 66.3% in Prospera and 144.1% in Amethyst under FR light compared to white light, and fresh biomass increasing by 59.3% and 120.1%, respectively. However, FR light increased photosystem II (PSII) efficiency by 20.9% and 34.3% in Prospera and Amethyst, respectively, compared to high-intensity white light, indicating FR light’s impactful role on growth and photosynthetic performance. The volatile profiles were also significantly influenced by light treatments. FR light increased citral levels by 371.0% in Prospera, while allo-ocimene levels increased by 89.0% in Amethyst compared to the control. Sensory evaluations confirmed that basil grown under FR light had a stronger aromatic profile. In contrast, BL light reduced concentrations of certain volatiles, such as eugenol and linalool, leading to a milder aroma. These findings demonstrate that the light spectra can be strategically manipulated to optimize basil’s growth, morphology, and aromatic profile, aligning production with consumer preferences.