Evaluation of some chemical/biochemical compounds of leaf lettuce (Lactuca sativa L.) to the quality of radiant light in floating system

Abstract

In order to investigate the light quality of LED lamps on some of the composition of leaf lettuce, an experiment was conducted in randomized complete block with 3 replications. Lettuce transplants for 35 days were exposed to irradiation of six light spectra [red (R), blue (B), white (W), 1red:1blue (RB), 1Red: 1Blue: 1White (RBW) and Fluorescent (FL) (control)]. The results showed the quality of light was significant at 1% level on soluble sugars, starch, soluble proteins, nitrate concentration, total phenol, total flavonoid, total antioxidant capacity, anthocyanin and vitamin C levels. The maximum dry weight plant (13.8 g), soluble sugars (14.3 mg/g) and starch (13.0 mg/g) were observed in R treatment. The maximum protein (0.39 mg/g), total phenol (19.78 mg/100 g,), total flavonoid (17.68 mg/100 g), total antioxidant capacity (78.66%), anthocyanin (30 mg/100 g) and vitamin C (0.19 mg/100 g) appeared in B treatment. The highest and lowest nitrate concentration were observed in the R (85.5 mg/kg FW) and B (354.44 mg/kg FW), respectively. According to the results, it can be said that red light produces the necessary materials for the growth of the aerial part of the plant, and blue light produces the most secondary metabolites.