Abstract

Changes in the light spectrum evoke different morphogenetic responses in plant species, which are species-specific. The objective of this research was to evaluate the effect of monochromatic blue (B), monochromatic red (R), mixed light 1 (BGR1) (52% blue, 27% green and 21% red) compared to white light (BGR2) (29% blue, 53% green and 17% red and 1% far red) as a control at 55 µmol photons m-2 s-1 for 12 h of photoperiod on biomass, morphology, chlorophyll content, antioxidant capacity and total phenolic content in green leaf lettuce seedlings (‘Levistro’) before transplanting. Seedlings were grown in a chamber at constant temperature (20±1.2°C) and ambient humidity (33±6.4%). No significant differences were found in fresh mass and number of leaves. The dry matter content of seedlings treated with BGR1 and B was significantly higher than the control. In addition, seedlings under these same lights showed a flatter rosette compared to seedlings in control and R. The chlorophyll content of seedlings treated with BGR1 did not show significant differences compared to BGR2 (control). Both, antioxidant capacity and total phenolic content of seedlings grown under BGR1 and B were significantly higher compared to BGR2 (control). Blue and BGR1 lights favored the growth, morphology, antioxidant capacity and total phenol content of green lettuce seedlings.