Supplementary light with different wavelengths improved the monoterpenes aroma and quality traits of ‘Shine Muscat’ grape berries under facility cultivation

Monoterpenes are typical aroma components of muscat grapes and are closely related to lighting conditions. However, the changes of light quality and intensity in facility cultivation hinder their accumulation and grape quality development. This study investigated the effect of supplementing light (white, red, blue, red-blue, UV-A, UV-B) on the quality of facility cultivated 'Shine Muscat' grapes. Compared to normal lighting condition (CK), supplementary lights significantly altered grape basic characteristics, including reducing berries green hue (white, red, blue, red-blue) and organic acids contents, while increasing the total soluble solids, glucose and fructose contents. Notably, all lights except red significantly increased the contents of most monoterpenes and enhanced floral and fruity odor by sensory evaluation, with blue light being most effective. Additionally, free forms of linalool, trans-rose oxide, and geraniol were identified as key monoterpenes contributing to muscat flavor. PCA indicated that blue light was the best overall promoter of grape quality.