The Nutritional Value, Biochemical Traits, and Growth of Brassica oleracea Grown Under Red, Blue, and Combined Red–Blue LED Lighting

Brassica vegetables are in high demand because they are an essential nutrient source for humans. Glucosinolates (GSLs), a major bioactive compound found in Brassicaceae, are amino acid derivatives that contribute to the health benefits of these crops. Light quality plays a significant role in plant growth and metabolite synthesis, and light-emitting diodes (LEDs) as artificial light sources offer many benefits. This study examined three cultivars of leafy cabbage B. oleracea. var. acephala (Kale), B. oleracea var. viridis (collard), and B. oleracea var. capitata (cabbage) grown under different LED conditions (red, blue, and blue–red) in the growing chamber. The primary objective of this study was to identify the most effective LED light spectrum for promoting GSLs accumulation and enhancing the overall plant quality. The findings of this study demonstrate that LED lights can have varying impacts on the cultivars of leafy cabbage. The different light spectra had varying impacts on the parameters examined in this study. GSLs compounds, particularly glucobrassicin, showed the most significant increase under the blue light treatment, with a 61% increase compared to the control. The R&B (red and blue) light treatment was the most effective in improving the growth traits of the shoot and root in the Kale cultivar. For the collard cultivar, the R&B light increased the leaf length and width, whereas for the cabbage cultivar, it led to an increase in the number of leaves and chlorophyll index. These findings demonstrate that the specific light quality can have different effects on the phytochemical composition and morphological characteristics of the different leafy cabbage cultivars. The blue light spectrum was particularly effective in enhancing GSLs accumulation, while the combination of red and blue light provided the most beneficial effects on overall plant growth and development across the three cultivars studied. These results suggest that the metabolism and phytochemical properties of leafy cabbage cultivars depend on exposure to multiple factors, such as cultivar type and light quality. Therefore, R&B light was the most effective light for most traits and can be suggested for performance.