Effects of photoperiod on phytochemical profiles of four Ocimum basilicum genotypes in a hydroponic climate chamber

Introduction Ocimum basilicum L. (basil) is a widely used aromatic plant with recognized functional properties, largely attributed to its rich profile of bioactive secondary metabolites. As demand for year-round high-quality basil increases, alternative approaches that ensure consistent phytochemical profiles are needed. This study aimed to investigate how different photoperiod regimes (6:4, 16:8, and 18:6 h light:dark) affect the composition of volatile organic compounds (VOCs) released from fresh basil tissues, together with the accumulation of polyphenols, and anthocyanins in four basil genotypes ( Italian , Rosie , Greek , and Thai ) grown under controlled hydroponic conditions. Methods Basil plants were cultivated for 26 days in a programmable mini-climate cabinet (Horto 4 ), and their phytochemical composition was analyzed using HS-GC/MS and HPLC-UV techniques. Results Results showed that photoperiod significantly affected the accumulation of non-volatile compounds across genotypes. The Italian genotype under the 6:4 photoperiod exhibited the highest concentration of total polyphenols (7.96 mg/g d.w.), including chicoric (3.52 mg/g), rosmarinic (2.79 mg/g), and caffeic acids (0.42 mg/g). Anthocyanin levels in the Rosie genotype also decreased with longer light exposure, with pelargonidin/delphinidin-based pigments dropping from 0.84 mg/g under 6:4 to 0.24 mg/g under 18:6. In terms of VOCs, the Thai genotype showed a consistently high content of estragole (up to 90%) regardless of light exposure, while eucalyptol and β -pinene were predominant in the other genotypes. Discussion This work demonstrates that photoperiod modulation can serve as a controlled abiotic stressor to fine-tune the phytochemical composition of basil. It provides a framework for controlled-environment modulation of basil tissue phytochemistry, enabling consistent, “ready-to-eat” tissue quality with stable functional properties, supporting the principles of precision agriculture and farm-to-table innovation.