Qualidade de luz no crescimento, teor e composição química de óleo essencial de plantas de Ocimum Basilicum var. purpurascens cultivadas sob malhas fotoconversoras coloridas

Abstract

Purple basil (Ocimum basilicum var. purpurascens Benth.) arouses great industrial interest due to its phytochemical profile rich in essential oils. This study evaluated the effect of solar radiation spectral modulation on the vegetative growth and secondary metabolism of this variety. The experiment was conducted at the Federal University of Lavras (UFLA) in a completely randomized design, testing four treatments: full sun and blue, black, and red photoconverting nets with 50% irradiance. Harvesting occurred at 63 days after transplanting. Full sun maximized vegetative vigor, promoting increases of 459.8% in total dry mass (40.08 g plant⁻¹) and 828.6% in root dry mass compared to the black net. However, light quality was the primary modulator of biochemical pathways. The red net provided greater physiological balance, resulting in the highest chlorophyll and carotenoid contents, as well as an 18.6% increase in total phenolics (1.59 mg g⁻¹ GAE). Linalool consolidated as the major constituent of the essential oil across all environments. Blue radiation elicited the highest relative accumulation of linalool in the leaves (53.78%), while the red net optimized its concentration in the inflorescences (69.79%). Source–sink dynamics revealed that inflorescences are preferential metabolic sinks, with an essential oil content (0.87%) significantly higher than that of the leaves (0.17%). It is concluded that, although full sun maximizes biomass, under the conditions of this experiment, the red net stands out as the most suitable technology for combining growth with the optimization of high value-added bioactive compounds.