The distinct impact of multi-color LED light on nitrate, amino acid, soluble sugar and organic acid contents in red and green leaf lettuce cultivated in controlled environment

•Primary metabolites in lettuce interplay with nutritional value and safety of food.•Lettuce sensitivity to lighting spectrum is determined by its metabolic plasticity.•The effect of supplemental orange, green, yellow and UV-A light is cultivar specific.•Green light has moderate positive impact on nutritive primary metabolites in lettuce.•Green, orange and UV-A light has distinct effect on primary metabolites. In this study we explore the effects of multi-colour LED lighting spectrum on nutritive primary metabolites in green (‘Lobjoits green cos’) and red (‘Red cos’) leaf lettuce (Lactuca sativa L.), cultivated in controlled environment. The basal lighting, consisting of blue 455 nm, red 627 and 660 nm and far red 735 nm LEDs, was supplemented with UV-A 380 nm, green 510 nm, yellow 595 nm or orange 622 nm LED wavelengths at total photosynthetic photon flux density of 300 μmol m−2 s−1. Supplemental lighting colours did not affect lettuce growth; however had distinct impact on nitrite, amino acid, organic acid, and soluble sugar contents. Orange, green and UV-A light had differential effects on red and green leaf lettuce metabolism and interplay with nutritional value and safety of lettuce production. The metabolic response was cultivar specific; however green light had reasonable impact on the contents of nutritive primary metabolites in red and green leaf lettuce.