Role of Nano-Oxides and Light Sources in Secondary Metabolite Production of Gardenia Callus Cultured In Vitro

• Ahmad Hadi Hamza¹ • Makki N. Nayef²

  Author

This study was conducted at the Plant Tissue Culture Laboratory, Department of Horticulture and Landscape Design, College of Agriculture, Al-Qasim Green University, during the 2025–2026 research season. The objectives were to evaluate the effects of different light sources and selected nano-oxide compounds on the growth of Gardenia jasminoides L. cv. Veitchii callus and its accumulation of secondary metabolites under in vitro conditions.                                                                             

The experiment was arranged as a two-factor completely randomized design (CRD). The first factor comprised three light regimes—white fluorescent, red LED (610–700 nm), and blue LED (400–500 nm)—together with a complete darkness treatment. The second factor included zinc oxide nanoparticles (ZnO NPs) and copper oxide nanoparticles (CuO NPs), each at 0.25 mg·L⁻¹, alongside an untreated control.            

Results showed that red LED irradiation significantly outperformed all other light treatments in accumulating secondary metabolites, recording the highest means for quercetin (110.811 mg·g⁻¹ FW), rutin (91.389 mg·g⁻¹ FW), caffeic acid (80.333 mg·g⁻¹ FW), and total phenolic content (247.01 mg·g⁻¹ FW), while the darkness treatment consistently yielded the lowest values. ZnO NPs at 0.25 mg·L⁻¹ similarly surpassed CuO NPs and the control for all four traits. The interaction of red LED × ZnO NPs produced the highest concentrations across all secondary metabolites, while white fluorescent light combined with ZnO NPs yielded the highest callus fresh weight (4.229 g) and dry weight (0.226 g).                                                                                              

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