The Physiology, Growth and Essential Oil Content of Lemon Balm (Melissa officinalis L.) in Response to Different LED Treatments

Background: Light-emitting diodes (LEDs) are a promising technology that has enormous potential to improve irradiance efficiency and replace traditionally used horticultural lighting. Compared with traditional light sources (e.g., high-pressure sodium lamps metal halide lamps) in crop production, LEDs tends have long life, generate less heat waste providing the perfect spectrum for plant growth. Methods: This work sought investigate effect of using blue LED lights on growth development Lemon balm (Melissa officinalis L.) under sole-source lighting spectra. Lighting spectra were provided by differing combinations 4 different peak wavelengths, (Blue 435, Blue 450, Red 663 nm Green 540 nm) ratios (1.95:2.3:1 R: G: B 450 (white), 5: 1R: nm, 2.5:1 435 at PPFD 95 ìmol m-2 s-1 (PAR). Result: showed wavelength combination red ratio (2.5:1 B) white enhanced physiology lemon (i.e., significantly increased assimilation rate, stomatal conductance transpiration rate), consequently fresh dry shoot weight essential oil content.