Changes in Morphological, Physiological and Phytochemical Traits of Different Dill (Anethum graveolens L.) Cultivars as Affected by Light-Emitting Diodes

Dill is a fragrant vegetable containing various beneficial compounds for health. This research aims to evaluate the impact of various spectra of LED light on essential oil composition and morphological and physiological characteristics of three dill cultivars. LED light treatments included greenhouse light as control (C), blue (B), red (R), red + blue (RB), and white (W). RB light enhanced most physiological indicators investigated in this study, including photosynthetic pigments, phenols, flavonoids, and antioxidant capacity. Furthermore, electrolyte leakage in the three cultivars of Khomein, Isfahan, and Varamin decreased when exposed to RB light compared with C light. Under RB light, the essential oil contained more dill ether and α-phellandrene than in other light conditions. In general, light treatment with 75% R light and 25% B light had a noticeable impact on enhancing physiological features compared with other light spectrums. α-phellandrene levels increased in the Isfahan and Varamin cultivars under RB and B light conditions. Finally, the RB light and Khomein cultivars improved physiological features, whereas RB and R light in the Varamin and Isfahan cultivars are recommended for more essential oil compositions in functional food production.