LED Light Treatments Enhance the Synthesis of Bioactive Compounds in Salvia lavandulifolia Vahl

Salvia lavandulifolia Vahl., a species native to the Western Mediterranean, is valued for its bioactive compounds and beneficial biological properties. Commonly propagated in greenhouses, it may benefit from exposure to tailored light-emitting diode (LED) light to enhance antioxidant defense and metabolite production. This study examined the effects of various spectra on two S. lavandulifolia ecotypes from southeastern Spain. Plants were propagated in vitro and grown for 30 days under white, red, blue, red/blue (70:30), white/blue, or white/red LED light, under a 16/8 h light/dark photoperiod (light intensity of 115 µmol m^-2 s^-1). Photosynthetic pigments, enzymatic antioxidants (superoxide dismutase and catalase), non-enzymatic antioxidants (tocopherols and polyphenols), antioxidant capacity (FRAP and DPPH^•), and lipid peroxidation (MDA) were assessed. In ecotype 1, red LED light significantly increased the content of photosynthetic pigments and non-enzymatic antioxidants while reducing enzymatic antioxidant activity. In contrast, ecotype 2 showed higher catalase and non-enzymatic antioxidant activity under white/blue light, without changes in pigment content. In both ecotypes, these treatments increased α-tocopherol and hydroxycinnamic acid derivative content, strengthening antioxidant defenses without inducing oxidative damage. Overall, the results highlight the need to customize LED light spectra for each ecotype, as genetic background may significantly influence plant responses.