Green-synthesized cobalt oxide nanoparticles for seed nanopriming enhance chickpea growth and suppress fusarium wilt

Abstract Background Chickpea ( Cicer arietinum L.) productivity is severely constrained by Fusarium wilt caused by Fusarium oxysporum f. sp. ciceris , and eco-friendly seed treatments are needed. Cobalt oxide nanoparticles (CoO-NPs) were green-synthesized using Ficus carica leaf extract and characterized by UV–Vis, FTIR, TEM, EDS, DLS, zeta potential, XRD, and XPS analyses. Seeds were nanoprimed for 24 h with CoO-NP suspensions (0.2, 0.5, 0.7, 1.0 mg/L) or a distilled water control, grown for 25 days, and challenged with F. oxysporum . In vitro antifungal activity was assessed by disc diffusion. Data (n = 3 biological replicates) were analyzed by one-way ANOVA with Tukey’s HSD (p < 0.05). Results UV–Vis peaks at 199, 216, and 229 nm and FTIR Co–O bands at 500–700 cm⁻ 1 confirmed CoO-NP formation. TEM, EDS, DLS, zeta potential, XRD, and XPS further confirmed nanoscale morphology, elemental composition, colloidal behaviour, crystallinity, and surface chemical states of the synthesized CoO-NPs. Compared with the control, nanopriming at 0.5 mg/L increased shoot length and root length, while 0.7 mg/L produced the highest growth response. Disease severity decreased from 63% in infected control to 32.5% at 0.5 mg/L and 27.5% at 0.7 mg/L. Disc diffusion showed the largest inhibition zones at 0.7 mg/L (18.5 ± 0.5 mm) and 0.5 mg/L (17.0 ± 0.5 mm). Conclusions Fig-mediated CoO-NP seed priming at 0.5–0.7 mg/L simultaneously enhanced chickpea growth and suppressed Fusarium wilt under controlled conditions. The absence of a bulk cobalt control remains an important limitation; therefore, future studies should include equivalent ionic/bulk cobalt treatments to distinguish nano-specific effects from cobalt ion effects. Field validation, dose–response refinement, nodulation assessment, and mechanistic assays, including ROS, antioxidant enzymes, and defense genes, are recommended. Biosafety work should assess nanoparticle persistence and effects on beneficial rhizosphere microbes over multiple seasons.