Effect of Light Modification by Shading Nets on Yield, Composition, and Antioxidant Activity of Lavandula angustifolia Mill. Essential Oil

Abstract

In the present study, the yield, chemical composition, and biological activities of Lavandula angustifolia flower essential oil (LAFEO) and leaves (LALEO) under different shade nets (pearl, red, blue) with 40% shading index compared with non-shading (control-open field) plants were investigated. The essential oil (EO) was isolated using a Clevenger-type hydrodistillation and the chemical composition of isolated EO was determined by GC/MS and GC/FID analyses. The antioxidant activity was determined using the DPPH and FRAP assay. The highest EO yield was recorded in flowers from plants grown under pearl shade nets (4.62 mL/100 g p.m.) and in leaves under red nets (0.99 mL/100 g p.m.). The lowest EO content occurred in plant leaves (0.50 mL/100 g p.m.) and flowers (3.17 mL/100 g p.m.) from non-shaded (control) plants. The composition of lavender EO depended on both plant part and light conditions. Among the 47–59 identified compounds in LAFEO, the major constituents were 1,8-cineole (27.4–32.2%), linalool (24.7–27.3%), borneol (18.0–21.9%), and camphor (7.5–8.6%). In LALEO, 55–65 compounds were identified, with 1,8-cineole (30.4–39.8%), borneol (21.9–26.5%), camphor (11.3–13.9%), and linalool (6.0–8.6%) as the dominant constituents. Flower samples from non-shaded (control) plants showed moderate antioxidant activity, with EC50 values decreasing over time, indicating the highest activity among treatments tested. Conversely, plant leaves under pearl nets showed the lowest activity among samples, with an EC50 value of 42.40 mg/mL at 120 min, still within the moderate antioxidant activity range. LALEO showed higher FRAP values than flower oils, confirming a stronger reducing capacity. The highest activity was found in plant leaves under red nets (0.72 mg EFe2+/g) and in non-shaded plants (0.68 mg EFe2+/g), while the lowest occurred in flower samples from red (0.28 mg EFe2+/g) and pearl nets (0.33 mg EFe2+/g). Unlike the FRAP results, the DPPH assay showed relatively higher activity in flowers compared to leaves, though all samples exhibited moderate antioxidant capacity. Shading significantly increased essential oil yield; however, the effects of different color nets on essential oil quality require further investigation, although preliminary results indicate a potential reduction in undesirable constituents.