In Vitro Callus Response of Lavandula angustifolia 'Munstead' to Zinc Oxide Nanoparticles and Plant Growth Regulators

A laboratory trial was conducted to evaluate the impact of nanoparticulate zinc oxide (ZnONPs) and some plant growth regulators (PGRs) on the growth, biochemical characteristics, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) activities of in vitro lavender (Lavandula angustifolia) calli var. vera. ZnONPs were applied to lavender explants at different concentrations (0, 50, 100, 150, and 200) µg L⁻¹ in combination with 1.0 mg L-1 for each 2,4-D and BA. ZnONPs positively influenced fresh weight, dry weight, relative water content, callus growth, and zinc accumulation in calli. The application of 150 and 200 µg L⁻¹ was superior to induce the responses.  Supplementing   the media with 2,4-D and BA to the media further enhanced growth, particularly at 100 µg L⁻¹ ZnONPs. Moreover, ZnONPs increased DPPH activity, indicating their potential to improve the antioxidant capacity of lavender calli. However, higher concentrations of 200 µg L⁻¹ caused increased browning intensity, suggesting possible toxicity. These findings highlight the potential of ZnONPs as a beneficial supplement in lavender tissue culture, with optimal concentrations enhancing both growth and antioxidant production.