Effect of Zinc Oxide Nanoparticles on in Vitro Growth, Rooting and Antioxidant Enzyme Activities of Two Iraqi Grapevine Cultivars

Abstract

The present study evaluates the effects of zinc oxide nanoparticles (ZnO-NPs) on growth in vitro, rooting induced and antioxidant status using two cultivars of grapevine (Halwani and Kamali). The nodal explants (1.0–1.5 cm) were cultured on Murashige and Skoog (MS) media with different concentrations of ZnO-NPs (0, 25, 50 and 100 mg L⁻¹). Vegetative growth metrics, root system features (root length and fresh weight for both shoot as well as root portions), leaf chlorophyll content, and antioxidant enzyme activities were assessed six weeks after planting. Interpretation of the results through MPN indicated that ZnO-NPs affected growth and physiological parameters in a concentration dependent manner. Among the two cultivars ZnO-NP concentration (50 mg L⁻¹) produced maximum shoot multiplication rate, shoot length, number of leaves/plants, chlorophyll content, rooting efficiency as well as root formation and biomass accumulation. In Halwani, the shoot multiplication rate was particularly high at 119% compared to untreated controls. In response to the two cultivars, Halwani consistently yielded higher than Kamali in the same treatment. This suggests that higher concentration (100 mg L⁻¹ ZnO-NPs) exposure significantly increased the activities of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD), revealing oxidative stress. Above results indicate that moderate levels of ZnO-NPs significantly improve the efficiency of micropropagation and vigor in plants, while a relatively high concentration may cause phytotoxic effects. This led to identifying 50 mg L⁻¹ ZnO-NPs as the most suitable concentration for in vitro propagation of grapevine cultivars evaluated. As far as we are aware, this is the first research on how nano-ZnO affects grapevine genotypes in Iraq. The data also shows the experimental feasibility of ZnO-NPs and their application in grapevine micropropagation systems