Unveiling the biological activity of Ocimum basilicum through nano graphene oxide foliar application with chemical and organic fertilizers broadcasting

Achieving sustainable agricultural production through nanotechnology offers a promising approach to enhance both crop yield and quality. This study evaluated the effects of foliar graphene oxide nanoparticle (nGO) applications at 100, 200, 300, and 500 mg L⁻1 on the biological activity of basil (Ocimum basilicum L. var. dino) grown with chemical fertilizer (Ch) (NPK: 90:60:60 kg ha⁻1) or farmyard manure (F) (30 t ha⁻1). Field trials were arranged based on a split-plot design in the randomized complete block with three replications, consisting of 11 plots (Control, F, Ch, F + nGO100, F + nGO200, F + nGO300, F + nGO500, Ch + nGO100, Ch + nGO200, Ch + nGO300, Ch + nGO500). Over two years (2022–2023), two cuttings were conducted annually. Increasing nGO doses reduced essential oil (EO) content. GC/FID-MS analysis identified linalool (48.8–57.92%) as the predominant EO component, followed by eugenol (16.62–26.24%), 1,8-cineole (5.11–10.66%), cis-α-bergamotene (3.37–8.05%), and γ-cadinene (1.38–2.67%). While nGO did not affect leaf extract antioxidant activity, it significantly influenced EO samples. While the highest DPPH and FRAP activities of EO were 68.22% and 253.5 µg TEs ml⁻1, respectively, these parameters were found to be 88.35% and 250.30 µg TEs mg⁻1 for the extracts. The highest total phenolic content (TPC) and flavonoids (TFC) in extracts were 96.09 µg GAE mg⁻1 and 8.78 µg QE mg⁻1, respectively. FT-IR analysis revealed no detectable nGO residues in the dried leaves. The principal component analysis (PCA) and heatmap analyses segregated applications into four groups, explaining 60.5% variance in basil’s antioxidant and EO profiles.