Bioinspired copper nanoparticles synthesized using Trichoderma asperellum secondary metabolites for the management of soil-borne fungal pathogens of chickpea ( Cicer arietinum L.)

Copper-based nanoparticles (CuNPs) were biosynthesized using secondary metabolites of Trichoderma asperellum isolates as reducing and stabilising agents, with copper sulphate pentahydrate (CuSO4·5H2O) as the precursor.Nanoparticles formation was confirmed by a colour change and plasmon resonance peak at 530 nm. FTIR analysis revealed the involvement of alcohol, amine, carboxyl, ester and aromatic functional groups . HR-TEM and SAED analyses demonstrated nanoflake-shaped particles with sizes ranging from 50–100 nm and a face-centered cubic crystalline structure. SEM–EDS analysis confirmed t copper, t oxygen and chlorine, while zeta potential analysis showed a surface charge of −4.92 mV, indicating limited colloidal stability. The CuNPs showed concentration dependent antifungal activity against Fusarium oxysporum f. sp. ciceri, Rhizoctonia bataticola, and Sclerotium rolfsii using agar well and paper disc diffusion assays. Tra05 -derived CuNPs showed greatest inhibitory activity, particularly at 500 ppm, against all three pathogens. Under greenhouse conditions, e 100 ppm CuNPs improved seedling emergence and reduced disease incidence whereas concentrations above 400 ppm adversely affected seed germination and seedling establishment, indicating concentration-dependent phytotoxicity. These findings demonstrate the potential of T. asperellum-mediated CuNPs for sustainable management of soil-borne fungal pathogens of chickpea. Nevertheless, further investigations on nanoparticle stabilisation, antifungal mechanisms, environmental safety and multi-location field validation are required before recommending their large-scale agricultural application.