Effects of different types of artificial light on the phytochemicals of Lactuca sativa L. Variety Great Lakes 118 cultivated under aeroponic system

Abstract

Lettuce is extensively researched in artificial lighting systems due to its efficient growth and phytochemical composition influenced by different spectra photon flux. This research focuses on the Great Lakes 118 variety and addresses the impact of white-blue (WB), white-red-far-red (WRI), and blue-red-far-red (BRI) light treatments in aeroponic systems. Digital foliar area, transmittance, and fluorescence measurements were completed with lettuce leaf hydromethanolic extract characterization using infrared and gas chromatography-mass spectroscopy (GC-MS). Results showed significant effects on physiological parameters of nitrogen balance index (NBI), chlo- rophyll (CHL), and anthocyanin (ANTH) contents. WB led to 63.3% and 21.2% higher NBI and CHL than BRI treatment, while WRI showed similar percentages concerning BRI. WB and WRI showed 17.9% and 38.8% upper ANTH contents than BRI. On the other hand, flavonoids (FLAV) did not indicate significant treatment-dependent. BRI exhibited several positive correlations among physiological parameters, suggesting its contribution to improved plant development. Infrared analysis revealed similarities in functional groups between treatments, although WB presented a more significant peak in their infrared spectra. GC-MS evidenced differences in the phytochemical profiles, with 2-imidazolidinethione, guanazine, and 3-ethyl-2,2-dimethyl-oxazolidine being the most abundant compounds in WRI, BRI, and WB-treated plants, respectively. The reported findings suggest that BRI may be the preferred artificial irradiation option.