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Abstract
Common basil is well known for its aromatic and medicinal properties. This study was aimed to investigate effects of light spectrum on essential oil composition, antiradical activity and total phenolic and anthocyanin contents of green and purple varieties of Ocimum basilicum. Plants were placed under different spectral light compositions including red (R), blue (B), white (W), 50 % red+50 % blue (50:50 % R:B) and 70 % red+30 % blue (70:30 % R:B) provided by LED modules with same light intensity for a duration of 30 days. Antiradical activity, total phenolic and anthocyanin contents and essential oil composition were measured using the DPPH radical scavenging assay, Folin-Ciocalteu reagent, spectrophotometric and GC-MS methods, respectively. Growing both basil varieties under 70:30 % R:B light resulted in higher antiradical activity than that of other light spectra. Highest amount of total phenolic and anthocyanin contents were observed in leaves of plants grown under 70:30 % R:B light in green and purple varieties, respectively. GC-MS analysis showed that essential oil compounds in both basil varieties were influenced by spectral light composition. In green basil, chemical composition of essential oil was improved by growing them under 70:30 % R:B light, while in purple variety R light induced production of limonene, α-pinene and β-myrcene. Close correlations were found between some essential oil compounds in plants grown under different light spectra. The effects of light spectra on bioactive compounds were depended on variety and type of compound. Therefore, through exposure to specific light spectrum it is possible to alter bioactive compound composition in basil plants.