Green synthesized silver nanoparticles from floral waste of Tagetes patula for mitigation of Meloidogyne incognita stress in tomato plants

Meloidogyne incognita ( M. incognita ) is a destructive plant parasitic nematode causing severe crop losses worldwide. This study aims to evaluate the potential of Tagetes patula - mediated silver nanoparticles (TP@Ag NPs) as an eco-friendly nematicidal and plant growth-promoting agent against M. incognita infection in Solanum lycopersicum L. seedlings. Silver nanoparticles were synthesized using T. patula petal extract and characterized by UV–visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy with selected area electron diffraction, dynamic light scattering and zeta potential analysis. The synthesis process produced a yield of ~ 42.4 mg NP per g biomass (including both metallic silver and phytogenic components), resulting in stable silver nanoparticles with no detectable residual silver nitrate. Mortality bioassays revealed that TP@Ag NPs induced a clear dose- and time-dependent nematicidal response, with maximum juvenile mortality of 97.66% observed at 50 ppm within 24 h ( p < 0.01). Nematode-infested seedlings treated with TP@Ag NPs showed improved growth as well as biochemical attributes, enhanced photosynthetic pigment levels (~ 240% increase in chlorophyll a, b and total chlorophyll content at p < 0.01) and elevated antioxidant enzyme activities as compared to untreated infected controls. Confocal microscopy indicated increased glutathione levels, reduced hydrogen peroxide accumulation and improved cell viability. This study demonstrates the potential of green-synthesized silver nanoparticles from T. patula petals to simultaneously manage M. incognita stress and promote plant growth in tomato.