Growing demand for edible flowers that combine aesthetic appeal and functional benefits has prompted research on light-based strategies to improve their quality. This study examined the impact of varying blue (B) light exposure on morphological traits, antioxidant activity, and phytochemical accumulation in two Viola cultivars with different petal sizes. Plants were cultivated under a 12-h daily photoperiod, with irradiation duration via white (W) and B LEDs varied among treatments (W12+B0, W8+B4, W4+B8, and W0+B12) while maintaining constant light intensity. Results indicated that prolonged B light exposure significantly increased plant height and flowering rate, particularly in the smaller-petaled cultivar “Delta Beaconsfield” (DB), and also enhanced anthocyanin accumulation and ABTS-based antioxidant activity. Conversely, the cultivar “Delta Trueblue” exhibited higher total phenolic and flavonoid levels under mixed W+B light illumination and showed stronger DPPH radical scavenging capacity. Notably, DB retained elevated chlorophyll levels under monochromatic B light, suggesting a unique photoadaptive or light-harvesting mechanism. The cultivars differing responses across assays highlight variation in light-regulated synthesis of hydrophilic and lipophilic antioxidants. These findings emphasize the potential of spectral manipulation, especially through B light, to improve the functional value of edible Viola flowers.

Introduction
Materials and Methods
    Plant samples
    Artificial light treatment
    Biological assays of plant growth
    Sample extraction
    DPPH and ABTS assays
    Determination of total phenolic and total flavonoidcontent
    Colorimetric assay of total anthocyanin content
    Statistical analysis
Results
    Vegetative growth and inflorescent properties
    DPPH and ABTS radical-scavenging activities
    Total phenolic, total flavonoid, and total anthocyanincontent
    Correlation analysis and PCA
Discussion
Conclusion
References

• Sunho Jang(Department of Horticulture, Kongju National University, Yesan 32439, Korea)
• Chan Saem Gil(Department of Horticulture, Kongju National University, Yesan 32439, Korea) Corresponding author