Effect of Blue Led Light Photoperiod on the Synthesis of Bioactive Pigments in Arugula Microgreens

Objectives: This study aimed to determine the optimal blue light photoperiod and cultivation time to maximize the synthesis of bioactive pigments (chlorophylls, carotenoids, flavonoids, and anthocyanins) in arugula (Eruca sativa) microgreens grown under blue LED lighting. Theoretical Framework: Microgreens are recognized for their high nutritional value and nutraceutical potential, often containing higher levels of phytonutrients than mature plants. Light quality and quantity, especially the blue spectrum, directly influence plant morphology and chemical composition, stimulating the biosynthesis of key pigments essential for plant metabolism and human health. Method: Arugula microgreens were cultivated in a growth chamber under five blue LED photoperiods (10, 12, 14, 16, and 18 hours per day), evaluated from the 4th to the 8th day after sowing. The experimental design was completely randomized, with three replicates. Pigment contents were determined by spectrophotometry, and the data were analyzed using variance and regression analyses. Results and Discussion: Maximum chlorophyll a accumulation was observed on the 8th day with 14 hours of light, while chlorophyll b peaked on the 7th day with approximately 13.7 hours. Total chlorophyll increased over time, with the highest value under 16 hours of light. Carotenoids accumulated most between 12 and 14 hours of exposure but decreased with longer photoperiods. Flavonoids and anthocyanins showed higher levels at 14 and 18 hours and 12 hours, respectively. The 14-hour photoperiod provided the best balance among bioactive pigments. Research Implications: The results indicate that manipulating the blue LED photoperiod can be an effective strategy to optimize the nutritional and functional quality of arugula microgreens, contributing to more sustainable and technologically advanced production systems. Originality/Value: This study provides novel data on the influence of blue light photoperiod on the synthesis of bioactive pigments in arugula microgreens, offering insights for artificial lighting management in controlled cultivation and adding value to the final product.