Effect of nano zinc and nano iron applications on morphological, physiological and biochemical characteristics of basil plant under drought stress

In this study, the effects of nano zinc and nano iron applications on morphological development, as well as the biochemical and physiological parameters, of basil (Ocimum basilicum L.) plants under drought stress were investigated. The experiment was conducted in a semi-controlled greenhouse at the Faculty of Agriculture, Bolu Abant İzzet Baysal University, using the "Dino" cultivar of basil obtained from AG Tohum company. The experimental design included two irrigation levels (100% and 50% field capacity) and four nanoparticle treatments (control, Zn NP, Fe NP, and Zn+Fe NP), with three replications. Zn and Fe nanoparticles were synthesized via a green biosynthesis method using sage (Salvia officinalis L.) extract and characterized by SEM and EDS analyses. According to the results, all nanoparticle treatments had positive effects on plant height and biomass, while the highest increase in leaf number and leaf weight was observed with the Zn+Fe NP treatment. Fe NP and Zn NP applications significantly enhanced SOD enzyme activity. The highest values for total phenol and flavonoid contents, as well as CAT and APX enzyme activities, were recorded under 50% irrigation in the Zn+Fe NP treatment. In contrast, the highest levels of MDA and H₂O₂ were observed in the control group without nanoparticle application under the same irrigation regime. In the evaluation of antioxidant capacity, the highest values in all DPPH, FRAP, and CUPRAC assays were determined in the Zn NP treatment, and this treatment was placed in the statistically highest group. Zn+Fe NP application resulted in the highest levels of total chlorophyll and carotenoid content. Overall, the findings indicate that Zn and Fe nanoparticles can enhance drought tolerance in plants by alleviating oxidative damage. In this context, the study highlights the potential of nanotechnology in sustainable agricultural practices.